ETSI EN 301 605 V1.1.1 (2013-10)
Environmental Engineering (EE); Earthing and bonding of 400 VDC data and telecom (ICT) equipment
Environmental Engineering (EE); Earthing and bonding of 400 VDC data and telecom (ICT) equipment
DEN/EE-02045
Okoljski inženiring (EE) - Ozemljitev in spajanje 400 VDC podatkovne in telekomunikacijske (IKT) opreme
Ta dokument se uporablja za ozemljitev in spajanje podatkovne in telekomunikacijske (IKT) opreme, vgrajene v podatkovnih in telekomunikacijskih središčih in podobnih objektih, ki delujejo v okviru razpona napetosti ob normalni uporabi do 400 VDC, kot je opredeljeno v standardu EN 300 132-3-1 [1]. V tem dokumenti so obravnavani ozemljitveno in spajalno omrežje stavbe (CBN), spajalno omrežje opreme (SRPP) in medsebojna povezava med tema dvema omrežjema. Prispeva k standardizaciji vgradnje telekomunikacijske in podatkovno-komunikacijske opreme.
Usklajuje tudi predpogoje za vgradnjo, da se dosežejo naslednji cilji:
– varnost pred nevarnostmi zaradi elektrike;
– neprekinjeno delovanje, pri čemer se zahteva:
– zanesljiva signalna referenca;
– zadovoljivo delovanje na področju elektromagnetne združljivosti (EMC).
Ta dokument določa konfiguracijo ozemljitve in spajanja vse do ravni opreme, da bi se olajšala vgradnja, delovanje in vzdrževanje podatkovnih in telekomunikacijskih središč v podatkovnih in telekomunikacijskih stavbah ali podobnih objektih, neodvisno od dobavitelja opreme. Specifikacija opreme IKT in predpogojev za vgradnjo je predmet dogovora med strankami (npr. med dobaviteljem in kupcem). Dodatek A je mogoče uporabiti v postopku za doseganje dogovora. Ta dokument ne obravnava vidikov varnosti in elektromagnetne združljivosti opreme. Te vidike obravnavajo drugi ustrezni standardi. Ta dokument se uporablja za vgradnjo opreme IKT v podatkovnih in telekomunikacijskih središčih. Ta dokument se lahko uporablja tudi za opremo IKT na drugih lokacijah, npr.:
– cestne omarice;
– vsebniki;
– stavba naročnika;
– zbiralčni razdelilniki (BTS).
General Information
Standards Content (Sample)
Draft ETSI EN 301 605 V1.1.1 (2013-01)
European Standard
Environmental Engineering (EE);
Earthing and bonding of 400 VDC data and telecom
(ICT) equipment
2 Draft ETSI EN 301 605 V1.1.1 (2013-01)
Reference
DEN/EE-02045
Keywords
bonding, earthing, power
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3 Draft ETSI EN 301 605 V1.1.1 (2013-01)
Contents
Intellectual Property Rights . 5
Foreword . 5
Introduction . 6
1 Scope . 7
2 References . 7
2.1 Normative references . 7
2.2 Informative references . 8
3 Definitions and abbreviations . 8
3.1 Definitions . 8
3.1.1 IEC definitions . 8
3.1.2 Other definitions . 10
3.2 Abbreviations . 11
4 General requirements . 12
4.1 Safety from electrical hazards . 12
4.2 Signal reference . 13
4.3 EMC performance . 13
5 Requirements on bonding networks . 13
5.1 Bonding configurations . 13
5.2 CBN within a building for data and telecom centres . 13
5.3 BN within a data and telecom centre . 14
5.4 Merging of CBN and MESH-BNs . 16
5.5 Cabling within and between BNs . 16
6 Requirements for power distribution . 16
6.1 DC power distribution of secondary supply . 16
6.1.1 General . 16
6.1.2 System earthing arrangement . 17
6.1.2.1 IT system with earthed high-ohmic mid-point (MP) terminal . 17
6.1.2.2 TN-S system with earthed negative line terminal (L-) . 18
6.2 DC power distribution of tertiary supplies . 19
6.3 AC mains distribution and bonding of the protective conductor . 20
6.4 AC power distribution from tertiary power supply . 20
Annex A (normative): Rationale about CBN co-ordination . 21
Annex B (normative): Requirements for fault protection . 22
B.1 Protective earthing . 22
B.1.1 TN and TT System Earthing. 22
B.1.2 IT System Earthing . 22
B.1.2.1 First fault on one of the live conductors . 22
B.1.2.2 Second fault on a different live conductor . 23
B.2 Protective equipotential bonding . 24
Annex C (informative): Coexistence of -48 VDC/-60 VDC DC-C (2-wire) and 400 VDC class I
equipment in MESH-BN . 25
Annex D (informative): Conductor arrangement and system earthing . 27
D.1 General remarks . 29
D.2 Ease of ground fault detection with high ohmic mid-point . 30
D.2.1 IT system with (L-) grounded via high impedance . 30
D.2.2 IT system with earthed high-ohmic mid-point (MP) terminal . 31
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4 Draft ETSI EN 301 605 V1.1.1 (2013-01)
D.3 Impact on body current due to a large number of loads . 31
Annex E (normative): AC mains distribution and bonding of the protective conductor . 33
Annex F (normative): Basic protection and Fault protection . 36
F.1 Basic protection (protection against direct contact) . 36
F.1.1 Basic insulation of live parts . 36
F.2 Fault protection (protection against indirect contact) . 36
F.2.1 Automatic disconnection in case of a fault . 36
F.3 Conclusions . 37
Annex G (informative): Bibliography . 38
History . 39
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5 Draft ETSI EN 301 605 V1.1.1 (2013-01)
Intellectual Property Rights
IPRs essential or potentially essential to the present document may have been declared to ETSI. The information
pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found
in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in
respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web
server (http://ipr.etsi.org).
Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee
can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web
server) which are, or may be, or may become, essential to the present document.
Foreword
This draft European Standard (EN) has been produced by ETSI Technical Committee Environmental Engineering (EE),
and is now submitted for the combined Public Enquiry and Vote phase of the ETSI standards EN Approval Procedure.
The present document has been produced within the framework of the following considerations:
a) Datacommunications and Telecommunications (ICT) equipment is generally installed in data and telecom
centres and held in racks, cabinets or other mechanical structures;
b) the existing ITU-T and CCIR Recommendations and CENELEC standards in such matters do not ensure the
required standardization at the equipment level;
c) network operators and equipment providers agreed to standardize on a bonding configuration that facilitates:
- compliance with functional requirements including Electromagnetic Compatibility (EMC) aspects of
emission and immunity;
- compatible building and equipment provisions;
- installation of new data and telecom centres as well as expansion or replacement of installations in
existing data and telecom centres with equipment coming from different suppliers;
- a structured installation practice;
- simple maintenance rules;
- contracting on a common basis;
- cost effectiveness in development, manufacturing, installation and operation.
Proposed national transposition dates
Date of latest announcement of this EN (doa): 3 months after ETSI publication
Date of latest publication of new National Standard
or endorsement of this EN (dop/e): 6 months after doa
Date of withdrawal of any conflicting National Standard (dow): 6 months after doa
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6 Draft ETSI EN 301 605 V1.1.1 (2013-01)
Introduction
The present document addresses earthing and bonding of data and telecom (ICT) equipment in data and telecom centres
when implementing a direct current interface up to 400 VDC defined in EN 300 132-3-1 [1] in relation to safety,
functional performance and EMC. The present standard may also be applicable for ICT equipment in other locations
such as: street cabinets, containers, subscriber's buildings, BTS:s etc.
The general principles for electrical installations from a safety perspective are based on the IEC 60364-series of
standards, and where appropriate on information published by ITU-T to provide for the proper functioning of those
installations.
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7 Draft ETSI EN 301 605 V1.1.1 (2013-01)
1 Scope
The present document applies to earthing and bonding of ICT equipment installed in data and telecom centres and
similar installations operating within the normal service voltage range up to 400 VDC defined in EN 300 132-3-1 [1].
Earthing and bonding network of the building (CBN), the bonding network of the equipment (SRPP), and the
interconnection between these two networks are treated in the present document. It contributes to the standardization of
telecommunication and datacom equipment installation.
It also co-ordinates with the pre-conditions of the installation to achieve the following targets:
• safety from electrical hazards;
• continuity of service requiring:
- reliable signal reference;
- satisfactory Electromagnetic Compatibility (EMC) performance.
The present document defines earthing and bonding configuration down to the equipment level in order to facilitate the
installation, operation and maintenance of data and telecom centres in data and telecom buildings or similar installations
independent of the equipment supplier.
The specification of ICT equipment and of the pre-conditions of installation is subject to agreement of the parties
(e.g. the supplier and the purchaser). Annex A can be used in the procedure to achieve an agreement.
The present document does not cover safety and EMC aspects of the equipment. Those aspects are covered by other
relevant standards.
The present document applies to the installation of ICT equipment in data and telecom centres. The present standard
may also be applicable for ICT equipment in other locations, e.g.:
• street cabinet
• container
• subscriber's building
• BTS
2 References
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
referenced document (including any amendments) applies.
Referenced documents which are not found to be publicly available in the expected location might be found at
http://docbox.etsi.org/Reference.
NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee
their long term validity.
2.1 Normative references
The following referenced documents are necessary for the application of the present document.
[1] ETSI EN 300 132-3-1: "Environmental Engineering (EE); Power supply interface at the input to
telecommunications and datacom (ICT) equipment; Part 3: Operated by rectified current source,
alternating current source or direct current source up to 400 V; Sub-part 1: Direct current source
up to 400 V".
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8 Draft ETSI EN 301 605 V1.1.1 (2013-01)
[2] IEC 60364-1: "Low-voltage electrical installations - Part 1: Fundamental principles, assessment of
general characteristics, definitions".
[3] IEC 60364-4-41: "Low-voltage electrical installations - Part 4-41: Protection for safety -
Protection against electric shock".
[4] IEC 60364-5-54: "Low-voltage electrical installations - Part 5-54: Selection and erection of
electrical equipment - Earthing arrangements and protective conductors".
[5] IEC 60050: "International Electrotechnical Vocabulary".
[6] IEC 60950-1: "Information technology equipment - Safety - Part 1: General requirements".
[7] IEC 62305-series: "Protection against lightning".
[8] CENELEC EN 50310: "Application of equipotential bonding and earthing in buildings with
information technology equipment".
[9] ETSI EN 300 253: "Environmental Engineering (EE); Earthing and bonding of telecommunication
equipment in telecommunication centres".
[10] CENELEC EN 41003: "Particular safety requirements for equipment to be connected to
telecommunication networks and/or a cable distribution system".
[11] IEC/TR 60479-5: "Effects of current on human beings and livestock - Part 5: Touch voltage
threshold values for physiological effects".
[12] CENELEC EN 50174-2: "Information technology -Cabling installation -Part 2: Installation
planning and practices inside buildings".
[13] CENELEC EN 50162:"Protection against corrosion by stray current from direct current systems".
2.2 Informative references
The following referenced documents are not necessary for the application of the present document but they assist the
user with regard to a particular subject area.
[i.1] ITU-T Recommendation K.27: "Bonding configurations and earthing inside a telecommunication
building".
[i.2] CENELEC EN 55022: "Information technology equipment - Radio disturbance characteristics -
Limits and methods of measurement".
[i.3] ITU-T Recommendation L.1200: "Specification of DC power feeding system interface".
3 Definitions and abbreviations
3.1 Definitions
For the purposes of the present document, the following terms and definitions apply:
3.1.1 IEC definitions
The following definitions (IEC reference in parentheses) with respect to earthing and bonding are introduced by the
IEC 60050 [5] and are used within the present document to maintain conformity.
earth (195-01-03): part of the Earth which is in electric contact with an earth electrode and the electric potential of
which is not necessarily equal to zero earthing arrangement
earthing conductor (195-02-03): conductor which provides a conductive path, or part of the conductive path, between
a given point in a system or in an installation or in equipment and an earth electrode
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9 Draft ETSI EN 301 605 V1.1.1 (2013-01)
earth electrode (195-02-01): conductive part, which may be embedded in a specific conductive medium, e.g. concrete
or coke, in electric contact with the Earth
earthing network (604-04-07): part of an earthing installation that is restricted to the earth electrodes and their
interconnections
equipotential bonding (195-01-10): provision of electric connections between conductive parts, intended to achieve
equipotentiality
exposed-conductive-part (826-12-10): conductive part of equipment which can be touched and which is not normally
live, but which can become live when basic insulation fails
extraneous-conductive-parts (195-06-11): conductive part not forming part of the electrical installation and liable to
introduce an electric potential, generally the electric potential of a local earth
functional-equipotential-bonding (826-13-21): equipotential bonding for operational reasons other than safety
insulation monitoring device (IMD): monitoring device sending an alarm when the insulation leakage current attains a
given value under specified conditions without interrupting the power supply
line conductor (826-14-09): conductor which is energized in normal operation and capable of contributing to the
transmission or distribution of electric energy but which is not a neutral or mid-point conductor
live part (826-12-08): conductor or conductive part intended to be energized in normal operation, including a neutral
conductor, but by convention not a PEN conductor or PEM conductor or PEL conductor
main earthing terminal (826-13-15): terminal or busbar which is part of the earthing arrangement of an installation
and enabling the electric connection of a number of conductors for earthing purposes
mid-point (MP) (826-14-04): common point between two symmetrical circuit elements whose opposite ends are
electrically connected to different line conductors of the same circuit
NOTE: MP is an abbreviation for "mid-point" defined and used in the present document.
mid-point conductor (M) (826-14-08): conductor electrically connected to the mid-point and capable of contributing
to the distribution of electric energy
neutral conductor (N) (826-01-03): conductor connected to the neutral point of a system and capable of contributing to
the transmission of electrical energy
PEN conductor (826-13-25): conductor combining the functions of both a protective earthing conductor and a neutral
conductor
PEM conductor (826-13-26): conductor combining the functions of both a protective earthing conductor and a mid-
point conductor
PEL conductor (826-13-27): conductor combining the functions of both a protective earthing conductor and a line
conductor
protective bonding conductor (195-02-10): protective conductor provided for protective-equipotential-bonding
protective earthing conductor (PE) (826-13-23): protective conductor provided for protective earthing
protective-equipotential-bonding (826-13-20): equipotential bonding for the purposes of safety
residual current device (RCD) (442-05-02): mechanical switching device designed to make, carry and break currents
under normal service conditions and to cause the opening of the contacts when the residual current attains a given value
under specified conditions
residual current monitoring device (RCM) : monitoring device sending an alarm when the residual current attains a
given value under specified conditions without interrupting the power supply
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10 Draft ETSI EN 301 605 V1.1.1 (2013-01)
IT, TN-C, TN-S, and TT systems (see IEC 60364-1 [2]): The codes used have the following meanings:
First letter – Relationship of the power system to earth:
T = direct connection of one point to earth;
I = all live parts isolated from earth, or one point connected to earth through a high impedance.
Second letter – Relationship of the exposed-conductive-parts of the installation to earth:
T = direct electrical connection of exposed-conductive-parts to earth, independently of the earthing of any point of the
power system;
N = direct electrical connection of the exposed-conductive-parts to the earthed point of the power system
Subsequent letter(s) (if any) – Arrangement of neutral and protective conductors:
S = protective function provided by a conductor separate from the neutral conductor or from the earthed line conductor.
C = neutral and protective functions combined in a single conductor (PEN conductor).
3.1.2 Other definitions
The following definitions, specific to telecommunication installations and not covered by the IEC 60050 [5], are used
within the present document. Correspondence to ITU-T Recommendation K.27 [i.1] and ETSI are indicated where
appropriate.
bonding mat: essential means to provide a SRPP by a discernible, nearly regular mesh structure
NOTE: The bonding mat may be located either below or above a collection of equipment constituting a system
block.
Bonding Network (BN), (ITU-T Recommendation K.27 [i.1]): set of interconnected conductive structures that
provides an "electromagnetic shield" for electronic systems and personnel at frequencies from Direct Current (DC) to
low Radio Frequency (RF)
NOTE: The term "electromagnetic shield" denotes any structure used to divert, block or impede the passage of
electromagnetic energy. In general, a BN need not be connected to earth but all BNs considered in the
present document will have an earth connection.
Common Bonding Network (CBN), (ITU-T Recommendation K.27 [i.1]): principal means for effective bonding and
earthing inside a telecommunication building
NOTE: It is the set of metallic components that are intentionally or incidentally interconnected to form the
principal BN in a building. These components include: structural steel or reinforcing rods, metallic
plumbing, Alternating Current (AC) power conduit, PE conductors, cable racks and bonding conductors.
The CBN always has a mesh topology and is connected to the earthing network.
DC return conductor: (L-) conductor of the +400 VDC secondary DC supply and (L+) conductor of the -48 V or
-60 V secondary DC supply
NOTE: The DC conductor may or may not be connected to earth.
Isolated Bonding Network (IBN): bonding network that has a single point of connection ("SPC") to either the
common bonding network or another isolated bonding network
NOTE: All IBNs considered here will have a connection to earth via the SPC.
ICT equipment: ICT refers to technologies that provide access to information through telecommunications. It is
similar to Information Technology (IT), but focuses primarily on communication technologies. This includes the
Internet, wireless networks, cell phones, and other communication mediums.
MESHed Bonding Network (MESH-BN), (ITU-T Recommendation K.27 [i.1]): bonding network in which all
associated equipment frames, racks and cabinets and usually the DC power return conductor, are bonded together as
well as at multiple points to the CBN
NOTE 1: Consequently, the MESH-BN augments the CBN.
NOTE 2: See Figure 1 of the present document.
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11 Draft ETSI EN 301 605 V1.1.1 (2013-01)
MESHed Isolated Bonding Network (MESH-IBN), (ITU-T Recommendation K.27 [i.1]): type of IBN in which the
components of the IBN (e.g. equipment frames) are interconnected to form a mesh-like structure
NOTE: This may, for example, be achieved by multiple interconnections between cabinet rows, or by connecting
all equipment frames to a metallic grid (a "bonding mat") extending beneath the equipment. The bonding
mat is, of course, insulated from the adjacent CBN. If necessary the bonding mat could include vertical
extensions, resulting in an approximation to a Faraday cage. The spacing of the grid is chosen according
to the frequency range of the electromagnetic environment.
normal service voltage range: range of the steady-state voltage at the A3 interface over which the equipment will
maintain normal service
NOTE: A3 as defined in EN 300 132-3-1 [1].
power supply:
- primary supply: public mains or, under emergency conditions, a locally generated AC supply
- secondary supply: supply to the ICT equipment, racks or system block, derived from the primary supply
- tertiary supplies: supplies to the ICT equipment, derived from the secondary supply
system: regularly interacting or interdependent group of items forming a unified whole
system block: functional group of equipment depending in its operation and performance on its connection to the same
system reference potential plane, inherent to a MESH-BN
System Reference Potential Plane (SRPP): conductive solid plane, as an ideal goal in potential equalizing, is
approached in practice by horizontal or vertical meshes
NOTE 1: The mesh width thereof is adapted to the frequency range to be considered. Horizontal and vertical
meshes may be interconnected to form a grid structure approximating to a Faraday cage.
NOTE 2: The SRPP facilitates signalling with reference to a common potential.
3.2 Abbreviations
For the purposes of the present document, the following abbreviations apply:
AC Alternating Current
BN Bonding Network
BTS Base Transceiver Station
CB Circuit Breaker
CBN Common Bonding Network
CM Common Mode
DC Direct Current
DC-C Common DC return (2-wire)
DC-I Isolated DC return (3-wire)
EMC ElectroMagnetic Compatibility
IBN Isolated Bonding Network
ICT Information and Communication Technology
IEC International Electrotechnical Commission
IMD Insulation Monitoring Device
IT See section 3.1.1 IEC Definitions.
ITU-T International Telecommunication Union-Telecommunication
LPS Lightning Protection System
M Mid-point conductor
MESH-BN MESHed Bonding Network
MESH-IBN MESHed Isolated Bonding Network
MET Main Earthing Terminal
MP Mid-Point
N Neutral conductor
PE Protective Earthing conductor
PEL combined Protective Earthing conductor and Line conductor
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12 Draft ETSI EN 301 605 V1.1.1 (2013-01)
PELV Protective Extra Low Voltage
PEM combined Protective Earthing conductor and Mid-point conductor
PEN combined Protective Earthing conductor and Neutral conductor
RCD Residual Current Device
RCM Residual Current Monitoring device
RF Radio Frequency
SELV Safety Extra Low Voltage
SRPP System Reference Potential Plane
TN See section 3.1.1 IEC Definitions
TN-C See section 3.1.1 IEC Definitions.
TN-S See section 3.1.1 IEC Definitions.
TT See section 3.1.1 IEC Definitions.
VAC Volts Alternating Current
VDC Volts Direct Current
4 General requirements
The earthing and bonding arrangements for 400 VDC interface A3 (stipulated in EN 300 132-3-1 [1]) treated in the
present document are intended to be implemented on new sites as well as on existing sites.
NOTE 1: The interface A3 is equivalent to the interface X in ITU-T Recommendation L.1200 [i.3].
The earthing and bonding arrangements for 400 VDC interface A3 are intended to co-exist with the earthing and
bonding arrangements according to EN 300 253 [9] valid for -48 VDC interface A and according to EN 50310 [8] valid
for ICT equipment powered by 230 VAC, without any adverse effects on safety and continuity of service.
NOTE 2: If no specific voltage is stated in connection to expressions like "ICT equipment" , "ICT system", etc. in
the text below, the normal service voltage range for interface A3 is presumed as defined in
EN 300 132-3-1 [1].
4.1 Safety from electrical hazards
IEC 60364 series of standards lay down the rules for the design, erection, and verification of electrical installations.
These standards shall be complied with to provide for safety of persons and property against dangers and damage which
may arise in the electrical installations and to provide for the proper functioning of those installations.
The installation material involved shall provide sufficiently high voltage, current, temperature ratings according to the
relevant safety standards to avoid electric shock, risk of fire, or damage to the equipment under normal or faulty
operating conditions within an equipment or the distribution network, or due to the impact of induced voltage and
current, e.g. by lightning.
The design of ICT equipment shall meet relevant product standard such as IEC 60950-1 [6] and EN 41003 [10].
• For safety reasons all exposed-conductive-parts (e.g. equipment chassis) of 400 VDC ICT equipment (class I)
shall be provided with a protective earthing conductor (PE).
Class II equipment with conductive chassis shall either be galvanically isolated from the chassis of class I equipment or
be provided with a protective earthing conductor (PE). For these reasons only ICT equipment of type "class I" are
recommended and presumed for the earthing arrangement presented in the present document.
The conductors involved shall provide sufficiently high current conducting capability and low impedance according to
the relevant safety standards to avoid electric shock, risk of fire, or damage to the equipment under normal or faulty
operating conditions within an equipment or the distribution network, or due to the impact of induced voltage and
current, e.g. by lightning. See references IEC 60364-5-54 [4] and EN 50174-2 [12].
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13 Draft ETSI EN 301 605 V1.1.1 (2013-01)
4.2 Signal reference
Reliable signal reference shall be provided by a SRPP dedicated at least to a functional unit or a system block. To avoid
undue functional distortion or risk of component failure, the SRPP shall provide sufficiently low impedance up to the
highest frequency to be regarded by using a metal plane or a meshed configuration having adequate mesh dimensions,
e.g. a bonding mat. The frequency band to be covered shall include the spectral components of transients caused by
switching, short circuits and atmospheric discharges.
NOTE: Signal reference to the SRPP does not always imply signal return via the SRPP.
4.3 EMC performance
Measures to gain a satisfactory EMC performance shall be assisted by a SRPP. The SRPP shall provide sufficiently low
impedance for efficient connection of filters, cabinets and cable shields. The requirement to avoid undue emission of or
susceptibility to electromagnetic energy under normal operating conditions may govern the properties of the SRPP
ahead of what is required in clause 4.2. The EMC requirements addressed include the discharge of electrostatic energy.
NOTE: Relevant safety standards allow a class I equipment to have Y-capacitors as decoupling capacitance from
the line and neutral conductor respectively to exposed conductive parts. Due to this fact class I equipment
is normally much easier to comply with the class B EMC requirements. See reference EN 55022 [i.2].
5 Requirements on bonding networks
5.1 Bonding configurations
Bonding configurations can be addressed at a building level (i.e. CBN), at an installation level (i.e. merging of CBN and
MESHed Bonding Network (MESH-BN)) and at an equipment level (i.e. MESH-BN).
ITU-T Recommendation K.27 [i.1] deals with bonding configurations of -48 VDC powered telecommunication
equipment. Bonding configuration for 400 VDC at equipment, installation and building level shall explicitly be
implemented as MESH-BN according to the directives in the present document.
NOTE: Other earthing topologies than MESH-BN are not in the scope of the present document, but are covered
in ITU-T Recommendation K.27 [i.1], such as Star-IBN and MESH-IBN, which sometimes are
implemented.
5.2 CBN within a building for data and telecom centres
Each building for telecom and data centres shall be provided with a CBN having sufficiently low impedance and high
current conducting capability to meet the general requirements of clause 4.
The earthing conductor and the equipotential bonding conductors should be coloured in accordance to international and
national regulations.
The main earthing terminal of the CBN shall be extended by a bonding ring conductor along the inside perimeter of the
building. As a basic element of the CBN, a ring conductor shall at least comprise the system block by its outer
perimeter. An extension of the ICT equipment installation inside a building requires to augment such a minimum CBN
version into a three dimensional grid structure, approximating a Faraday cage (see Figure 1). The impact of interfering
energy in an exposed location or the need for information security enforces the provision of shielded rooms as a
maximum requirement to the CBN.
For further details about earthing and bonding arrangement in buildings refer to the publication IEC 60364-5-54 [4].
Annex A gives information about the implementation principles for the CBN, thereby following ITU-T
Recommendation K.27 [i.1], clause 4.2.1.
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14 Draft ETSI EN 301 605 V1.1.1 (2013-01)
5.3 BN within a data and telecom centre
Within a system block of ICT equipment and between different system blocks, the BN shall be of the mesh type. The
MESH-BN shall provide sufficiently low impedance and high current conducting capability to meet the general
requirements in clause 4.
The MESH-BN shall interconnect shelves, cabinets, rack rows, cable racks, ducts, distribution frames, cable shields and
bonding mat to constitute the required SRPP.
All metallic parts of the MESH-BN shall form an electrically continuous whole. This does not necessarily require
bonding by additional bonding straps, but that improvements should be taken into account when determining the
finishes and fastening methods to be used. The mechanical structure comprised by the MESH-BN shall form part of the
SRPP.
As an example, Figure 2 addresses interconnections within a system block, essential to a MESH-BN. This example
follows the implementation principles for the MESH-BN outlined in ITU-T Recommendation K.27 [i.1], clause 4.2.2.
The cable shields shall be connected to the rack.
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15 Draft ETSI EN 301 605 V1.1.1 (2013-01)
2-wire
3-wire
Earthed
high-ohmic
MP
mid-point
-
+
terminal
±200 Vdc +400 Vdc -48 Vdc
IT TN-S
+400 Vdc return (0 Vdc)
-48 Vdc return (0 Vdc)
Protective Earth (PE)
Interconnected reinforcement
and building steel
Intra-system cabling
Shielded inter-system cabling
Bonding conductor
Figure 1: Example of a CBN/MESH-BN installation inside a telecommunication building
ETSI
16 Draft ETSI EN 301 605 V1.1.1 (2013-01)
5.4 Merging of CBN and MESH-BNs
All BNs of ICT systems and their associated protective earthing conductors shall be connected to the CBN.
The MESH-BN shall augment the CBN including the main earthing terminal by multiple interconnections to the CBN
(see Figure 1).
5.5 Cabling within and between BNs
Power distribution cables and signal cables within and between MESH-BNs shall be run tightly along the members of
the augmented CBN.
There shall be a separation distance of at least 100 mm between groups of AC mains cables and groups of signal cables
on one and the same cable rack, unless adequate shielding is provided.
Cable shields shall be bonded directly to racks, cabinets or to the dedicated SRPP at least at each end. Circumferential
connections are most effective and therefore are recommended.
NOTE: It is recognized that where a new system has to be cabled to existing equipment, it has previously been
considered feasible to avoid the connection of cable shields at the existing equipment end. However, the
consequent solution of the present document is to provide a lower impedance path via improved bonding
between the equipment locations, thereby enabling connection of cable shields at least at each end.
6 Requirements for power distribution
6.1 DC power distribution of secondary supply
6.1.1 General
The DC power distribution shall route line conductors close together. Live parts, including each line conductor (L+ and
L-) shall be completely covered with insulation which can only be removed by destruction. The insulation is intended to
prevent contact with live parts.
The laying of the DC power distribution shall comply with relevant installation standards concerning voltage rating,
ambient temperature and current carrying capacity of the cables.
The ICT equipment, the insulation shall comply with the relevant product standard.
Exposed-conductive-parts shall be connected to a protective earthing conductor (PE) under the specific conditions for
each type of system earthing as specified below in Figure 1.
The line conductor and the protective earthing conductor shall be capable of carrying over-currents in the case of a fault
between a line conductor of the 400 VDC secondary supply and the MESH-BN. See IEC 60364-5-54 [4].
Simultaneously accessible exposed-conductive-parts shall be collectively earthed to the same earthing system of which
the MESH-BN is an integral part.
The maximum DC voltage drop along each dedicated DC power return conductor for -48 VDC arrangements shall be
designed to be less than 1 V. The calculation shall take into account the maximum load current on the associated supply
conductor at maximum or minimum source voltage respectively under normal operating conditions.
NOTE: One concern of this requirement is to avoid electrochemical corrosion by stray currents.
See EN 50162 [13].
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17 Draft ETSI EN 301 605 V1.1.1 (2013-01)
6.1.2 System earthing arrangement
The definitions used in this clause are based on IEC 60364-1 [2].
The DC power distribution of the secondary supply serving the ICT system shall conform to the requirements of the IT
or TN-S system.
6.1.2.1 IT system with earthed high-ohmic mid-point (MP) terminal
Figure 3 shows a preferred symmetrical IT system earthing arrangement for 400 VDC. This arrangement is based on
the IT system earthing type 2 according to IEC 60364-1 [2] (see Figure E.2 in Annex E) but modified for adaptation to
one 400 V power source instead of a series connection of two 200 V power sources.
The high-ohmic mid-point terminal (MP) of the power plant powering the ICT equipment shall be connected to the
Main Earthing Terminal (MET).
The high-ohmic mid-point terminal (MP) is the common point between two symmetrical high-ohmic resistors
(typically > 50 kΩ ) whose opposite ends are electrically connected to the different line conductors (L+ and L-) of the
same circuit.
In cases where an IT system is used for reasons of continuity of supply, automatic disconnection is not usually required
on the occurrence of a first fault (single fault) to an exposed-conductive-part or to earth. This is valid on condition that
an Insulation Monitoring Device (IMD) or a Residual Current Monitoring device (RCM) indicates the first fault by an
audible and/or visual signal which shall continue as long as the fault persists. See further requirements in Annex B.
After the occurrence of a first fault, conditions for automatic disconnection of supply in the event of a second fault
occurring on a different live conductor shall be as stipulated in normative clause B.1.2.
MPMP
HO
Figure 2: IT system with earthed high-ohmic mid-point terminal (MP)
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18 Draft ETSI EN 301 605 V1.1.1 (2013-01)
Figure 3 illustrates an implementation of "IT system with earthed high-ohmic mid-point terminal (MP)" from the power
source via the cable system to the ICT equipment. The main Earthing Terminal (MET) is the common earthing point for
the high-ohmic mid-point (MP) of the source as well as for the protective earthing conductor (PE).
Power source Cable system ICT
L+
L-
PE
Option a)
Option b)
MPMP
HO
Local Earth
MET
Option a): Disconnection time for 2nd fault as for TN-S system earthing in accordance with IEC 60364-4-41, clause 411.6.4 a)
Option b): Disconnection time for 2nd fault as for TT system earthing in accordance with IEC 60364-4-41, clause 411.6.4 b)
Figure 3: Implementation of IT system with earthed high-ohmic mid-point (MP) terminal
6.1.2.2 TN-S system with earthed negative line terminal (L-)
Figure 4 shows a possible system earthing arrangements (TN-S) for 400 VDC according to IEC 60364-1 [2].
The negative line terminals ( L-) of the power plant powering the ICT equipment shall be is connected to the Main
Earthing Terminal (MET).
The earthed line conductors (L-) shall be separated from the PE-conductor throughout the installation.
In TN-S system earthing a protective device shall automatically interrupt the supply to the line conductor of a circuit or
equipment in the event of a fault of negligible impedance between the line conductor and an exposed-conductive-part
within the disconnection time required. See clause B.1.1.
Annex A gives information about necessary agreements if DC return-co
...
Final draft ETSI EN 301 605 V1.1.1 (2013-07)
European Standard
Environmental Engineering (EE);
Earthing and bonding of 400 VDC data and
telecom (ICT) equipment
2 Final draft ETSI EN 301 605 V1.1.1 (2013-07)
Reference
DEN/EE-02045
Keywords
bonding, earthing, power
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ETSI
3 Final draft ETSI EN 301 605 V1.1.1 (2013-07)
Contents
Intellectual Property Rights . 5
Foreword . 5
Introduction . 6
1 Scope . 7
2 References . 7
2.1 Normative references . 7
2.2 Informative references . 8
3 Definitions and abbreviations . 9
3.1 Definitions . 9
3.1.1 IEC definitions . 9
3.1.2 Other definitions . 10
3.2 Abbreviations . 11
4 General requirements . 12
4.1 Safety from electrical hazards . 12
4.2 Signal reference . 13
4.3 EMC performance . 13
5 Requirements on bonding networks . 13
5.1 Bonding configurations . 13
5.2 CBN within a building for data and telecom centres . 13
5.3 BN within a data and telecom centre . 14
5.4 Merging of CBN and MESH-BNs . 16
5.5 Cabling within and between BNs . 16
6 Requirements for power distribution . 16
6.1 DC power distribution of secondary supply . 16
6.1.1 General . 16
6.1.2 System earthing arrangement . 16
6.1.2.1 IT system with earthed high-ohmic mid-point (MP) terminal . 17
6.1.2.2 TN-S system with earthed negative line terminal (L-) . 18
6.2 DC power distribution of tertiary supplies . 19
6.3 AC mains distribution and bonding of the protective conductor . 20
6.4 AC power distribution from tertiary power supply . 20
Annex A (normative): Rationale about CBN co-ordination . 21
Annex B (normative): Requirements for fault protection . 22
B.1 Protective earthing . 22
B.1.1 TN and TT System Earthing. 22
B.1.2 IT System Earthing . 22
B.1.2.1 First fault on one of the live conductors . 22
B.1.2.2 Second fault on a different live conductor . 23
B.2 Protective equipotential bonding . 24
Annex C (informative): Coexistence of -48 VDC/-60 VDC DC-C (2-wire) and 400 VDC class I
equipment in MESH-BN . 25
Annex D (informative): Conductor arrangement and system earthing . 27
D.1 General remarks . 30
D.2 Ease of earth fault detection with high ohmic mid-point . 31
D.2.1 IT system with (L-) earthed via high impedance . 31
D.2.2 IT system with earthed high-ohmic mid-point (MP) terminal . 31
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4 Final draft ETSI EN 301 605 V1.1.1 (2013-07)
D.3 Impact on body current due to a large number of loads . 32
Annex E (normative): AC mains distribution and bonding of the protective conductor . 34
Annex F (normative): Basic protection and Fault protection . 37
F.1 Basic protection (protection against direct contact) . 37
F.1.1 Basic insulation of live parts . 37
F.2 Fault protection (protection against indirect contact) . 37
F.2.1 Automatic disconnection in case of a fault . 37
F.3 Conclusions . 38
Annex G (informative): Bibliography . 39
History . 40
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5 Final draft ETSI EN 301 605 V1.1.1 (2013-07)
Intellectual Property Rights
IPRs essential or potentially essential to the present document may have been declared to ETSI. The information
pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found
in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in
respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web
server (http://ipr.etsi.org).
Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee
can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web
server) which are, or may be, or may become, essential to the present document.
Foreword
This final draft European Standard (EN) has been produced by ETSI Technical Committee Environmental
Engineering (EE), and is now submitted for the Vote phase of the ETSI standards EN Approval Procedure.
The present document has been produced within the framework of the following considerations:
a) Datacommunications and Telecommunications (ICT) equipment is generally installed in data and telecom
centres and held in racks, cabinets or other mechanical structures;
b) the existing ITU-T and ITU-R Recommendations and CENELEC standards in such matters do not ensure the
required standardization at the equipment level;
c) network operators and equipment providers agreed to standardize on a bonding configuration that facilitates:
- compliance with functional requirements including Electromagnetic Compatibility (EMC) aspects of
emission and immunity;
- compatible building and equipment provisions;
- installation of new data and telecom centres as well as expansion or replacement of installations in
existing data and telecom centres with equipment coming from different suppliers;
- a structured installation practice;
- simple maintenance rules;
- contracting on a common basis;
- cost effectiveness in development, manufacturing, installation and operation.
Proposed national transposition dates
Date of latest announcement of this EN (doa): 3 months after ETSI publication
Date of latest publication of new National Standard
or endorsement of this EN (dop/e): 6 months after doa
Date of withdrawal of any conflicting National Standard (dow): 6 months after doa
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6 Final draft ETSI EN 301 605 V1.1.1 (2013-07)
Introduction
The present document addresses earthing and bonding of data and telecom (ICT) equipment in data and telecom centres
when implementing a direct current interface up to 400 VDC defined in EN 300 132-3-1 [1] in relation to safety,
functional performance and EMC. The present standard may also be applicable for ICT equipment in other locations
such as: street cabinets, containers, subscriber's buildings, BTSs, etc.
The general principles for electrical installations from a safety perspective are based on the HD 60364-series
(IEC 60364-series) of standards, and where appropriate on information published by ITU-T to provide for the proper
functioning of those installations.
The author thanks the International Electrotechnical Commission (IEC) for permission to reproduce Information from
its International Standard IEC 60364-1 ed. 5.0 (2005). All such extracts are copyright of IEC, Geneva, Switzerland. All
rights reserved. Further information on the IEC is available from www.iec.ch/. IEC has no responsibility for the
placement and context in which the extracts and contents are reproduced by the author, nor is IEC in any way
responsible for the other content or accuracy therein.
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7 Final draft ETSI EN 301 605 V1.1.1 (2013-07)
1 Scope
The present document applies to earthing and bonding of ICT equipment installed in data and telecom centres and
similar installations operating within the normal service voltage range up to 400 VDC defined in EN 300 132-3-1 [1].
Earthing and bonding network of the building (CBN), the bonding network of the equipment (SRPP), and the
interconnection between these two networks are treated in the present document. It contributes to the standardization of
telecommunication and datacom equipment installation.
It also co-ordinates with the pre-conditions of the installation to achieve the following targets:
• safety from electrical hazards;
• continuity of service requiring:
- reliable signal reference;
- satisfactory Electromagnetic Compatibility (EMC) performance.
The present document defines earthing and bonding configuration down to the equipment level in order to facilitate the
installation, operation and maintenance of data and telecom centres in data and telecom buildings or similar installations
independent of the equipment supplier.
The specification of ICT equipment and of the pre-conditions of installation is subject to agreement of the parties
(e.g. the supplier and the purchaser). Annex A can be used in the procedure to achieve an agreement.
The present document does not cover safety and EMC aspects of the equipment. Those aspects are covered by other
relevant standards.
The present document applies to the installation of ICT equipment in data and telecom centres. The present document
may also be applicable for ICT equipment in other locations, e.g.:
• street cabinet;
• container;
• subscriber's building;
• BTS.
2 References
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
referenced document (including any amendments) applies.
Referenced documents which are not found to be publicly available in the expected location might be found at
http://docbox.etsi.org/Reference.
NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee
their long term validity.
2.1 Normative references
The following referenced documents are necessary for the application of the present document.
[1] ETSI EN 300 132-3-1: "Environmental Engineering (EE); Power supply interface at the input to
telecommunications and datacom (ICT) equipment; Part 3: Operated by rectified current source,
alternating current source or direct current source up to 400 V; Sub-part 1: Direct current source
up to 400 V".
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8 Final draft ETSI EN 301 605 V1.1.1 (2013-07)
[2] CENELEC HD 60364-1: "Low-voltage electrical installations - Part 1: Fundamental principles,
assessment of general characteristics, definitions" (IEC 60364-1).
[3] CENELEC HD 60364-4-41: "Low-voltage electrical installations - Part 4-41: Protection for
safety - Protection against electric shock" (IEC 60364-4-41).
[4] CENELEC HD 60364-5-54: "Low-voltage electrical installations - Part 5-54: Selection and
erection of electrical equipment - Earthing arrangements and protective conductors"
(IEC 60364-5-54).
[5] IEC 60050: "International Electrotechnical Vocabulary".
[6] CENELEC EN 60950-1: "Information technology equipment - Safety - Part 1: General
requirements" (IEC 60950-1).
[7] CENELEC EN 62305-series: "Protection against lightning" (IEC 62305-series).
[8] CENELEC EN 50310: "Application of equipotential bonding and earthing in buildings with
information technology equipment".
[9] ETSI EN 300 253: "Environmental Engineering (EE); Earthing and bonding of telecommunication
equipment in telecommunication centres".
[10] CENELEC EN 41003: "Particular safety requirements for equipment to be connected to
telecommunication networks and/or a cable distribution system".
[11] IEC/TR 60479-5: "Effects of current on human beings and livestock - Part 5: Touch voltage
threshold values for physiological effects".
[12] CENELEC EN 50174-2: "Information technology -Cabling installation -Part 2: Installation
planning and practices inside buildings".
[13] CENELEC EN 61557-8: "Electrical safety in low voltage distribution systems up to 1 000 V a.c.
and 1 500 V d.c. - Equipment for testing, measuring or monitoring of protective measures -
Part 8: Insulation monitoring devices for IT systems" (IEC 61557-8).
[14] CENELEC EN 61557-9: "Electrical safety in low voltage distribution systems up to 1 000 V a.c.
and 1 500 V d.c. - Equipment for testing, measuring or monitoring of protective measures -
Part 9: Equipment for insulation fault location in IT systems" (IEC 61557-9).
[15] CENELEC HD 308: "Identification of cores in cables and flexible cords".
[16] CENELEC EN 60445: "Basic and safety principles for man-machine interface, marking and
identification - Identification of equipment terminals, conductor terminations and conductors"
(IEC 60445).
2.2 Informative references
The following referenced documents are not necessary for the application of the present document but they assist the
user with regard to a particular subject area.
[i.1] Recommendation ITU-T K.27: "Bonding configurations and earthing inside a telecommunication
building".
[i.2] CENELEC EN 55022: "Information technology equipment - Radio disturbance characteristics -
Limits and methods of measurement".
[i.3] Recommendation ITU-T L.1200: "Specification of DC power feeding system interface".
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9 Final draft ETSI EN 301 605 V1.1.1 (2013-07)
3 Definitions and abbreviations
3.1 Definitions
For the purposes of the present document, the following terms and definitions apply:
3.1.1 IEC definitions
The following definitions (IEC reference in parentheses) with respect to earthing and bonding are introduced by the
IEC 60050 [5] and are used within the present document to maintain conformity.
earth (195-01-03): part of the Earth which is in electric contact with an earth electrode and the electric potential of
which is not necessarily equal to zero earthing arrangement
earthing conductor (195-02-03): conductor which provides a conductive path, or part of the conductive path, between
a given point in a system or in an installation or in equipment and an earth electrode
earth electrode (195-02-01): conductive part, which may be embedded in a specific conductive medium, e.g. concrete
or coke, in electric contact with the Earth
earthing network (604-04-07): part of an earthing installation that is restricted to the earth electrodes and their
interconnections
equipotential bonding (195-01-10): provision of electric connections between conductive parts, intended to achieve
equipotentiality
exposed-conductive-part (826-12-10): conductive part of equipment which can be touched and which is not normally
live, but which can become live when basic insulation fails
extraneous-conductive-parts (195-06-11): conductive part not forming part of the electrical installation and liable to
introduce an electric potential, generally the electric potential of a local earth
functional-equipotential-bonding (826-13-21): equipotential bonding for operational reasons other than safety
insulation monitoring device (IMD): an IMD for IT systems defined in HD 60364-series gives a warning if the
insulation resistance R (including the insulation resistance of all the connected appliances) between the system live
F
conductors and earth falls below a predetermined level (response value R ). See EN 61557-8 [13]
a
line conductor (826-14-09): conductor which is energized in normal operation and capable of contributing to the
transmission or distribution of electric energy but which is not a neutral or mid-point conductor
live part (826-12-08): conductor or conductive part intended to be energized in normal operation, including a neutral
conductor, but by convention not a PEN conductor or PEM conductor or PEL conductor
main earthing terminal (826-13-15): terminal or busbar which is part of the earthing arrangement of an installation
and enabling the electric connection of a number of conductors for earthing purposes
mid-point (MP) (826-14-04): common point between two symmetrical circuit elements whose opposite ends are
electrically connected to different line conductors of the same circuit
NOTE: MP is an abbreviation for "mid-point" defined and used in the present document.
mid-point conductor (M) (826-14-08): conductor electrically connected to the mid-point and capable of contributing
to the distribution of electric energy
neutral conductor (N) (826-01-03): conductor connected to the neutral point of a system and capable of contributing to
the transmission of electrical energy
PEL conductor (826-13-27): conductor combining the functions of both a protective earthing conductor and a line
conductor
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10 Final draft ETSI EN 301 605 V1.1.1 (2013-07)
PEM conductor (826-13-26): conductor combining the functions of both a protective earthing conductor and a
mid-point conductor
PEN conductor (826-13-25): conductor combining the functions of both a protective earthing conductor and a neutral
conductor
protective bonding conductor (195-02-10): protective conductor provided for protective-equipotential-bonding
protective earthing conductor (PE) (826-13-23): protective conductor provided for protective earthing
protective-equipotential-bonding (826-13-20): equipotential bonding for the purposes of safety
residual current device (RCD) (442-05-02): mechanical switching device designed to make, carry and break currents
under normal service conditions and to cause the opening of the contacts when the residual current attains a given value
under specified conditions
IT, TN-C, TN-S, and TT systems (see HD 60364-1 [2]): The codes used have the following meanings:
First letter – Relationship of the power system to earth:
T = direct connection of one point to earth;
I = all live parts isolated from earth, or one point connected to earth through a high impedance.
Second letter – Relationship of the exposed-conductive-parts of the installation to earth:
T = direct electrical connection of exposed-conductive-parts to earth, independently of the earthing of any point of the
power system;
N = direct electrical connection of the exposed-conductive-parts to the earthed point of the power system
Subsequent letter(s) (if any) – Arrangement of neutral and protective conductors:
S = protective function provided by a conductor separate from the neutral conductor or from the earthed line conductor.
C = neutral and protective functions combined in a single conductor (PEN conductor).
3.1.2 Other definitions
The following definitions, specific to telecommunication installations and not covered by the IEC 60050 [5], are used
within the present document. Correspondence to Recommendation ITU-T K.27 [i.1] and ETSI are indicated where
appropriate.
bonding mat: essential means to provide a SRPP by a discernible, nearly regular mesh structure
NOTE: The bonding mat may be located either below or above a collection of equipment constituting a system
block.
Bonding Network (BN), (Recommendation ITU-T K.27 [i.1]): set of interconnected conductive structures that
provides an "electromagnetic shield" for electronic systems and personnel at frequencies from Direct Current (DC) to
low Radio Frequency (RF)
NOTE: The term "electromagnetic shield" denotes any structure used to divert, block or impede the passage of
electromagnetic energy. In general, a BN need not be connected to earth but all BNs considered in the
present document will have an earth connection.
Common Bonding Network (CBN), (Recommendation ITU-T K.27 [i.1]): principal means for effective bonding and
earthing inside a telecommunication building
NOTE: It is the set of metallic components that are intentionally or incidentally interconnected to form the
principal BN in a building. These components include: structural steel or reinforcing rods, metallic
plumbing, Alternating Current (AC) power conduit, PE conductors, cable racks and bonding conductors.
The CBN always has a mesh topology and is connected to the earthing network.
DC return conductor: (L-) conductor of the +400 VDC secondary DC supply and (L+) conductor of the -48 V or
-60 V secondary DC supply
NOTE: The DC conductor may or may not be connected to earth.
Isolated Bonding Network (IBN): bonding network that has a single point of connection ("SPC") to either the
common bonding network or another isolated bonding network
NOTE: All IBNs considered here will have a connection to earth via the SPC.
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11 Final draft ETSI EN 301 605 V1.1.1 (2013-07)
ICT equipment: equipment designed for Information and Communication Technologies
NOTE: It is similar to Information Technology (IT), but focuses primarily on communication technologies. This
includes the Internet, wireless networks, cell phones, and other communication mediums.
MESHed Bonding Network (MESH-BN), (Recommendation ITU-T K.27 [i.1]): bonding network in which all
associated equipment frames, racks and cabinets and usually the DC power return conductor, are bonded together as
well as at multiple points to the CBN
NOTE 1: Consequently, the MESH-BN augments the CBN.
NOTE 2: See Figure 1 of the present document.
MESHed Isolated Bonding Network (MESH-IBN), (Recommendation ITU-T K.27 [i.1]): type of IBN in which the
components of the IBN (e.g. equipment frames) are interconnected to form a mesh-like structure
NOTE: This may, for example, be achieved by multiple interconnections between cabinet rows, or by connecting
all equipment frames to a metallic grid (a "bonding mat") extending beneath the equipment. The bonding
mat is, of course, insulated from the adjacent CBN. If necessary the bonding mat could include vertical
extensions, resulting in an approximation to a Faraday cage. The spacing of the grid is chosen according
to the frequency range of the electromagnetic environment.
normal service voltage range: range of the steady-state voltage at the A3 interface over which the equipment will
maintain normal service
NOTE: A3 as defined in EN 300 132-3-1 [1].
power supply:
- primary supply: public mains or, under emergency conditions, a locally generated AC supply
- secondary supply: supply to the ICT equipment, racks or system block, derived from the primary supply
- tertiary supplies: supplies to the ICT equipment, derived from the secondary supply
system: regularly interacting or interdependent group of items forming a unified whole
system block: functional group of equipment depending in its operation and performance on its connection to the same
system reference potential plane, inherent to a MESH-BN
System Reference Potential Plane (SRPP): conductive solid plane, as an ideal goal in potential equalizing, is
approached in practice by horizontal or vertical meshes
NOTE 1: The mesh width thereof is adapted to the frequency range to be considered. Horizontal and vertical
meshes may be interconnected to form a grid structure approximating to a Faraday cage.
NOTE 2: The SRPP facilitates signalling with reference to a common potential.
3.2 Abbreviations
For the purposes of the present document, the following abbreviations apply:
AC Alternating Current
BN Bonding Network
BTS Base Transceiver Station
CB Circuit Breaker
CBN Common Bonding Network
CM Common Mode
DC Direct Current
DC-C Common DC return (2-wire)
DC-I Isolated DC return (3-wire)
EMC ElectroMagnetic Compatibility
IBN Isolated Bonding Network
ICT Information and Communication Technology
IEC International Electrotechnical Commission
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12 Final draft ETSI EN 301 605 V1.1.1 (2013-07)
IMD Insulation Monitoring Device
IT See clause 3.1.1.
ITU-T International Telecommunication Union-Telecommunication
LPS Lightning Protection System
M Mid-point conductor
MESH-BN MESHed Bonding Network
MESH-IBN MESHed Isolated Bonding Network
MET Main Earthing Terminal
MP Mid-Point
N Neutral conductor
PE Protective Earthing conductor
PEL combined Protective Earthing conductor and Line conductor
PELV Protective Extra Low Voltage
PEM combined Protective Earthing conductor and Mid-point conductor
PEN combined Protective Earthing conductor and Neutral conductor
RCD Residual Current Device
RF Radio Frequency
SELV Safety Extra Low Voltage
SRPP System Reference Potential Plane
TN See clause 3.1.1.
TN-C See clause 3.1.1.
TN-S See clause 3.1.1.
TT See clause 3.1.1.
VAC Volts Alternating Current
VDC Volts Direct Current
4 General requirements
The earthing and bonding arrangements for 400 VDC interface A3 (stipulated in EN 300 132-3-1 [1]) treated in the
present document are intended to be implemented on new sites as well as on existing sites.
NOTE 1: The interface A3 is equivalent to the interface P in Recommendation ITU-T L.1200 [i.3].
The earthing and bonding arrangements for 400 VDC interface A3 are intended to co-exist with the earthing and
bonding arrangements according to EN 300 253 [9] valid for -48 VDC interface A and according to EN 50310 [8] valid
for ICT equipment powered by 230 VAC, without any adverse effects on safety and continuity of service.
NOTE 2: If no specific voltage is stated in connection to expressions like "ICT equipment", "ICT system", etc. in
the text below, the normal service voltage range for interface A3 is presumed as defined in
EN 300 132-3-1 [1].
4.1 Safety from electrical hazards
HD 60364-series of standards lay down the rules for the design, erection, and verification of electrical installations.
These standards shall be complied with to provide for safety of persons and property against dangers and damage which
may arise in the electrical installations and to provide for the proper functioning of those installations.
The installation material involved shall provide sufficiently high voltage, current, temperature ratings according to the
relevant safety standards to avoid electric shock, risk of fire, or damage to the equipment under normal or faulty
operating conditions within an equipment or the distribution network, or due to the impact of induced voltage and
current, e.g. by lightning.
The design of ICT equipment shall meet relevant product standard such as EN 60950-1 [6] and EN 41003 [10].
• For safety reasons all exposed-conductive-parts (e.g. equipment chassis) of 400 VDC ICT equipment (class I)
shall be provided with a protective earthing conductor (PE).
Class II equipment with conductive chassis shall either be galvanically isolated from the chassis of class I equipment or
be provided with a protective earthing conductor (PE). For these reasons only ICT equipment of type "class I" are
recommended and presumed for the earthing arrangement presented in the present document.
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13 Final draft ETSI EN 301 605 V1.1.1 (2013-07)
The conductors involved shall provide sufficiently high current conducting capability and low impedance according to
the relevant safety standards to avoid electric shock, risk of fire, or damage to the equipment under normal or faulty
operating conditions within an equipment or the distribution network, or due to the impact of induced voltage and
current, e.g. by lightning. See references HD 60364-5-54 [4] and EN 50174-2 [12].
4.2 Signal reference
Reliable signal reference shall be provided by a SRPP dedicated at least to a functional unit or a system block. To avoid
undue functional distortion or risk of component failure, the SRPP shall provide sufficiently low impedance up to the
highest frequency to be regarded by using a metal plane or a meshed configuration having adequate mesh dimensions,
e.g. a bonding mat. The frequency band to be covered shall include the spectral components of transients caused by
switching, short circuits and atmospheric discharges.
NOTE: Signal reference to the SRPP does not always imply signal return via the SRPP.
4.3 EMC performance
Measures to gain a satisfactory EMC performance shall be assisted by a SRPP. The SRPP shall provide sufficiently low
impedance for efficient connection of filters, cabinets and cable shields. The requirement to avoid undue emission of or
susceptibility to electromagnetic energy under normal operating conditions may govern the properties of the SRPP
ahead of what is required in clause 4.2. The EMC requirements addressed include the discharge of electrostatic energy.
NOTE: Relevant safety standards allow a class I equipment to have Y-capacitors as decoupling capacitance from
the line and neutral conductor respectively to exposed conductive parts. Due to this fact class I equipment
is normally much easier to comply with the class B EMC requirements. See reference EN 55022 [i.2].
5 Requirements on bonding networks
5.1 Bonding configurations
Bonding configurations can be addressed at a building level (i.e. CBN), at an installation level (i.e. merging of CBN and
MESHed Bonding Network (MESH-BN)) and at an equipment level (i.e. MESH-BN).
Recommendation ITU-T K.27 [i.1] deals with bonding configurations of -48 VDC powered telecommunication
equipment. Bonding configuration for 400 VDC at equipment, installation and building level shall explicitly be
implemented as MESH-BN according to the directives in the present document.
NOTE: Other earthing topologies than MESH-BN are not in the scope of the present document, but are covered
in Recommendation ITU-T K.27 [i.1], such as Star-IBN and MESH-IBN, which sometimes are
implemented.
5.2 CBN within a building for data and telecom centres
Each building for telecom and data centres shall be provided with a CBN having sufficiently low impedance and high
current conducting capability to meet the general requirements of clause 4.
The earthing conductor and the equipotential bonding conductors should be coloured in accordance to international and
national regulations.
The main earthing terminal of the CBN shall be extended by a bonding ring conductor along the inside perimeter of the
building. As a basic element of the CBN, a ring conductor shall at least comprise the system block by its outer
perimeter. An extension of the ICT equipment installation inside a building requires to augment such a minimum CBN
version into a three dimensional grid structure, approximating a Faraday cage (see Figure 1). The impact of interfering
energy in an exposed location or the need for information security enforces the provision of shielded rooms as a
maximum requirement to the CBN.
For further details about earthing and bonding arrangement in buildings refer to the publication HD 60364-5-54 [4].
ETSI
14 Final draft ETSI EN 301 605 V1.1.1 (2013-07)
Annex A gives information about the implementation principles for the CBN, thereby following Recommendation
ITU-T K.27 [i.1], clause 4.2.1.
5.3 BN within a data and telecom centre
Within a system block of ICT equipment and between different system blocks, the BN shall be of the mesh type. The
MESH-BN shall provide sufficiently low impedance and high current conducting capability to meet the general
requirements in clause 4.
The MESH-BN shall interconnect shelves, cabinets, rack rows, cable racks, ducts, distribution frames, cable shields and
bonding mat to constitute the required SRPP.
All metallic parts of the MESH-BN shall form an electrically continuous whole. This does not necessarily require
bonding by additional bonding straps, but that improvements should be taken into account when determining the
finishes and fastening methods to be used. The mechanical structure comprised by the MESH-BN shall form part of the
SRPP.
As an example, Figure 1 addresses interconnections within a system block, essential to a MESH-BN. This example
follows the implementation principles for the MESH-BN outlined in Recommendation ITU-T K.27 [i.1], clause 4.2.2.
The cable shields shall be connected to the rack.
NOTE 1: With reference to Figure 1:
The live conductors:
-48 VDC in the "-48 VDC box"
+400 VDC in the "+400 VDC box"
+200 VDC and -200 VDC respectively in the "±200 VDC box"
are not routed in the figure, only return-conductors (0 VDC) and protective earth (PE).
NOTE 2: With reference to Figure 1:
The positive pole (L+) is earthed in the "-48 VDC box", while the negative pole (L-) is earthed in
the " +400 VDC box" (see clause 6.1.2.2).
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15 Final draft ETSI EN 301 605 V1.1.1 (2013-07)
L+L+L+
L-L-L-
2-2-wwiirree
3-3-wwiirree
OpOpttiioonnaall
ifif Mes Meshh--BBNN//CCBBNN
EaEarthrtheedd
hhiigghh--ohmohmiicc
MPMP
mimidd--ppooiinnt t
teterrmmiinnaall
±±200200 Vd Vdcc ++400 V400 Vddcc -4-488 V Vddcc
ITIT TTNN--SS
++440000 V Vddcc re retuturn (0rn (0 VVddc)c)
-48-48 V Vddcc ret retuurnrn (0 (0 V Vddcc))
PPrrootteeccttiivvee Ea Earrtthh ((PPE)E)
IInntetercrcononnenectcteded re reiinnffoorcrcememeenntt
anand bud buiillddiinngg sstteeeell
InInttrra-a-sysysstteemm ca cablbliinngg
SShhieieldldeedd in intteerr--ssyysstteemm ccaabblinlingg
BBoonnddiinng cog condnducuctotorr
Figure 1: Example of a CBN/MESH-BN installation inside a telecommunication building
ETSI
16 Final draft ETSI EN 301 605 V1.1.1 (2013-07)
5.4 Merging of CBN and MESH-BNs
All BNs of ICT systems and their associated protective earthing conductors shall be connected to the CBN.
The MESH-BN shall augment the CBN including the main earthing terminal by multiple interconnections to the CBN
(see Figure 1).
5.5 Cabling within and between BNs
Power distribution cables and signal cables within and between MESH-BNs shall be run tightly along the members of
the augmented CBN.
There shall be a separation distance of at least 100 mm between groups of AC mains cables and groups of signal cables
on one and the same cable rack, unless adequate shielding is provided.
Cable shields shall be bonded directly to racks, cabinets or to the dedicated SRPP at least at each end. Circumferential
connections are most effective and therefore are recommended.
NOTE: It is recognized that where a new system has to be cabled to existing equipment, it has previously been
considered feasible to avoid the connection of cable shields at the existing equipment end. However, the
consequent solution of the present document is to provide a lower impedance path via improved bonding
between the equipment locations, thereby enabling connection of cable shields at least at each end.
6 Requirements for power distribution
6.1 DC power distribution of secondary supply
6.1.1 General
The DC power distribution shall route line conductors close together. Live parts, including each line conductor (L+ and
L-) shall be completely covered with insulation which can only be removed by destruction. The insulation is intended to
prevent contact with live parts.
The laying of the DC power distribution shall comply with relevant installation standards concerning voltage rating,
ambient temperature and current carrying capacity of the cables.
The ICT equipment shall comply with the relevant product standard.
Exposed-conductive-parts shall be connected to a protective earthing conductor (PE) under the specific conditions for
each type of system earthing as specified below in clause 6.1.2.
The line conductor and the protective earthing conductor shall be capable of carrying over-currents in the case of a fault
between a line conductor of the 400 VDC secondary supply and the MESH-BN. See HD 60364-5-54 [4].
Simultaneously accessible exposed-conductive-parts shall be collectively earthed to the same earthing system of which
the MESH-BN is an integral part.
6.1.2 System earthing arrangement
The definitions used in this clause are based on HD 60364-1 [2].
The DC power distribution of the secondary supply serving the ICT system shall conform to the requirements of the IT
or TN-S system.
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17 Final draft ETSI EN 301 605 V1.1.1 (2013-07)
6.1.2.1 IT system with earthed high-ohmic mid-point (MP) terminal
Figure 2 shows a preferred symmetrical IT system earthing arrangement for 400 VDC. This arrangement is based on
the IT system earthing type b) according to HD 60364-1 [2] (see Figure D.2 in Annex D of the present document) but
modified for adaptation to one 400 V power source instead of a series connection of two 200 V power sources.
NOTE 1: Figure 2 is based on figure 31M – IT d.c. system, Type a) from IEC 60364-1 [2] and modified to a IT
system with an earthed high-ohmic mid-point terminal (MP).
The high-ohmic mid-point terminal (MP) of the power plant powering the ICT equipment shall be connected to the
Main Earthing Terminal (MET) for functional reasons.
The high-ohmic mid-point terminal (MP) is the common point between two symmetrical high-ohmic resistors
(typically > 50 kΩ ) whose opposite ends are electrically connected to the different line conductors (L+ and L-) of the
same circuit.
In cases where an IT system is used for reasons of continuity of supply, automatic disconnection is not usually required
on the occurrence of a first fault (single fault) to an exposed-conductive-part or to earth. This is valid on condition that
an insulation monitoring device (IMD) indicates the first fault by an audible and/or visual signal which shall continue as
long as the fault persists. See further requirements in Annex B.
After the occurrence of a first fault, conditions for automatic disconnection of supply in the event of a second fault
occurring on a different live conductor shall be as stipulated in normative clause B.1.2.
1)
...
European Standard
Environmental Engineering (EE);
Earthing and bonding of 400 VDC data and
telecom (ICT) equipment
2 ETSI EN 301 605 V1.1.1 (2013-10)
Reference
DEN/EE-02045
Keywords
bonding, earthing, power
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3 ETSI EN 301 605 V1.1.1 (2013-10)
Contents
Intellectual Property Rights . 5
Foreword . 5
Introduction . 6
1 Scope . 7
2 References . 7
2.1 Normative references . 7
2.2 Informative references . 8
3 Definitions and abbreviations . 9
3.1 Definitions . 9
3.1.1 IEC definitions . 9
3.1.2 Other definitions . 10
3.2 Abbreviations . 11
4 General requirements . 12
4.1 Safety from electrical hazards . 12
4.2 Signal reference . 13
4.3 EMC performance . 13
5 Requirements on bonding networks . 13
5.1 Bonding configurations . 13
5.2 CBN within a building for data and telecom centres . 13
5.3 BN within a data and telecom centre . 14
5.4 Merging of CBN and MESH-BNs . 16
5.5 Cabling within and between BNs . 16
6 Requirements for power distribution . 16
6.1 DC power distribution of secondary supply . 16
6.1.1 General . 16
6.1.2 System earthing arrangement . 16
6.1.2.1 IT system with earthed high-ohmic mid-point (MP) terminal . 17
6.1.2.2 TN-S system with earthed negative line terminal (L-) . 18
6.2 DC power distribution of tertiary supplies . 19
6.3 AC mains distribution and bonding of the protective conductor . 20
6.4 AC power distribution from tertiary power supply . 20
Annex A (normative): Rationale about CBN co-ordination . 21
Annex B (normative): Requirements for fault protection . 22
B.1 Protective earthing . 22
B.1.1 TN and TT System Earthing. 22
B.1.2 IT System Earthing . 22
B.1.2.1 First fault on one of the live conductors . 22
B.1.2.2 Second fault on a different live conductor . 23
B.2 Protective equipotential bonding . 24
Annex C (informative): Coexistence of -48 VDC/-60 VDC DC-C (2-wire) and 400 VDC class I
equipment in MESH-BN . 25
Annex D (informative): Conductor arrangement and system earthing . 27
D.1 General remarks . 30
D.2 Ease of earth fault detection with high ohmic mid-point . 31
D.2.1 IT system with (L-) earthed via high impedance . 31
D.2.2 IT system with earthed high-ohmic mid-point (MP) terminal . 31
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4 ETSI EN 301 605 V1.1.1 (2013-10)
D.3 Impact on body current due to a large number of loads . 32
Annex E (normative): AC mains distribution and bonding of the protective conductor . 34
Annex F (normative): Basic protection and Fault protection . 37
F.1 Basic protection (protection against direct contact) . 37
F.1.1 Basic insulation of live parts . 37
F.2 Fault protection (protection against indirect contact) . 37
F.2.1 Automatic disconnection in case of a fault . 37
F.3 Conclusions . 38
Annex G (informative): Bibliography . 39
History . 40
ETSI
5 ETSI EN 301 605 V1.1.1 (2013-10)
Intellectual Property Rights
IPRs essential or potentially essential to the present document may have been declared to ETSI. The information
pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found
in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in
respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web
server (http://ipr.etsi.org).
Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee
can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web
server) which are, or may be, or may become, essential to the present document.
Foreword
This European Standard (EN) has been produced by ETSI Technical Committee Environmental Engineering (EE).
The present document has been produced within the framework of the following considerations:
a) Datacommunications and Telecommunications (ICT) equipment is generally installed in data and telecom
centres and held in racks, cabinets or other mechanical structures;
b) the existing ITU-T and ITU-R Recommendations and CENELEC standards in such matters do not ensure the
required standardization at the equipment level;
c) network operators and equipment providers agreed to standardize on a bonding configuration that facilitates:
- compliance with functional requirements including Electromagnetic Compatibility (EMC) aspects of
emission and immunity;
- compatible building and equipment provisions;
- installation of new data and telecom centres as well as expansion or replacement of installations in
existing data and telecom centres with equipment coming from different suppliers;
- a structured installation practice;
- simple maintenance rules;
- contracting on a common basis;
- cost effectiveness in development, manufacturing, installation and operation.
National transposition dates
Date of adoption of this EN: 30 September 2013
Date of latest announcement of this EN (doa): 31 December 2013
Date of latest publication of new National Standard
or endorsement of this EN (dop/e): 30 June 2014
Date of withdrawal of any conflicting National Standard (dow): 30 June 2014
ETSI
6 ETSI EN 301 605 V1.1.1 (2013-10)
Introduction
The present document addresses earthing and bonding of data and telecom (ICT) equipment in data and telecom centres
when implementing a direct current interface up to 400 VDC defined in EN 300 132-3-1 [1] in relation to safety,
functional performance and EMC. The present standard may also be applicable for ICT equipment in other locations
such as: street cabinets, containers, subscriber's buildings, BTSs, etc.
The general principles for electrical installations from a safety perspective are based on the HD 60364-series
(IEC 60364-series) of standards, and where appropriate on information published by ITU-T to provide for the proper
functioning of those installations.
The author thanks the International Electrotechnical Commission (IEC) for permission to reproduce Information from
its International Standard IEC 60364-1 ed. 5.0 (2005). All such extracts are copyright of IEC, Geneva, Switzerland. All
rights reserved. Further information on the IEC is available from www.iec.ch/. IEC has no responsibility for the
placement and context in which the extracts and contents are reproduced by the author, nor is IEC in any way
responsible for the other content or accuracy therein.
ETSI
7 ETSI EN 301 605 V1.1.1 (2013-10)
1 Scope
The present document applies to earthing and bonding of ICT equipment installed in data and telecom centres and
similar installations operating within the normal service voltage range up to 400 VDC defined in EN 300 132-3-1 [1].
Earthing and bonding network of the building (CBN), the bonding network of the equipment (SRPP), and the
interconnection between these two networks are treated in the present document. It contributes to the standardization of
telecommunication and datacom equipment installation.
It also co-ordinates with the pre-conditions of the installation to achieve the following targets:
• safety from electrical hazards;
• continuity of service requiring:
- reliable signal reference;
- satisfactory Electromagnetic Compatibility (EMC) performance.
The present document defines earthing and bonding configuration down to the equipment level in order to facilitate the
installation, operation and maintenance of data and telecom centres in data and telecom buildings or similar installations
independent of the equipment supplier.
The specification of ICT equipment and of the pre-conditions of installation is subject to agreement of the parties
(e.g. the supplier and the purchaser). Annex A can be used in the procedure to achieve an agreement.
The present document does not cover safety and EMC aspects of the equipment. Those aspects are covered by other
relevant standards.
The present document applies to the installation of ICT equipment in data and telecom centres. The present document
may also be applicable for ICT equipment in other locations, e.g.:
• street cabinet;
• container;
• subscriber's building;
• BTS.
2 References
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
referenced document (including any amendments) applies.
Referenced documents which are not found to be publicly available in the expected location might be found at
http://docbox.etsi.org/Reference.
NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee
their long term validity.
2.1 Normative references
The following referenced documents are necessary for the application of the present document.
[1] ETSI EN 300 132-3-1: "Environmental Engineering (EE); Power supply interface at the input to
telecommunications and datacom (ICT) equipment; Part 3: Operated by rectified current source,
alternating current source or direct current source up to 400 V; Sub-part 1: Direct current source
up to 400 V".
ETSI
8 ETSI EN 301 605 V1.1.1 (2013-10)
[2] CENELEC HD 60364-1: "Low-voltage electrical installations - Part 1: Fundamental principles,
assessment of general characteristics, definitions" (IEC 60364-1).
[3] CENELEC HD 60364-4-41: "Low-voltage electrical installations - Part 4-41: Protection for
safety - Protection against electric shock" (IEC 60364-4-41).
[4] CENELEC HD 60364-5-54: "Low-voltage electrical installations - Part 5-54: Selection and
erection of electrical equipment - Earthing arrangements and protective conductors"
(IEC 60364-5-54).
[5] IEC 60050: "International Electrotechnical Vocabulary".
[6] CENELEC EN 60950-1: "Information technology equipment - Safety - Part 1: General
requirements" (IEC 60950-1).
[7] CENELEC EN 62305-series: "Protection against lightning" (IEC 62305-series).
[8] CENELEC EN 50310: "Application of equipotential bonding and earthing in buildings with
information technology equipment".
[9] ETSI EN 300 253: "Environmental Engineering (EE); Earthing and bonding of telecommunication
equipment in telecommunication centres".
[10] CENELEC EN 41003: "Particular safety requirements for equipment to be connected to
telecommunication networks and/or a cable distribution system".
[11] IEC/TR 60479-5: "Effects of current on human beings and livestock - Part 5: Touch voltage
threshold values for physiological effects".
[12] CENELEC EN 50174-2: "Information technology -Cabling installation -Part 2: Installation
planning and practices inside buildings".
[13] CENELEC EN 61557-8: "Electrical safety in low voltage distribution systems up to 1 000 V a.c.
and 1 500 V d.c. - Equipment for testing, measuring or monitoring of protective measures -
Part 8: Insulation monitoring devices for IT systems" (IEC 61557-8).
[14] CENELEC EN 61557-9: "Electrical safety in low voltage distribution systems up to 1 000 V a.c.
and 1 500 V d.c. - Equipment for testing, measuring or monitoring of protective measures -
Part 9: Equipment for insulation fault location in IT systems" (IEC 61557-9).
[15] CENELEC HD 308: "Identification of cores in cables and flexible cords".
[16] CENELEC EN 60445: "Basic and safety principles for man-machine interface, marking and
identification - Identification of equipment terminals, conductor terminations and conductors"
(IEC 60445).
2.2 Informative references
The following referenced documents are not necessary for the application of the present document but they assist the
user with regard to a particular subject area.
[i.1] Recommendation ITU-T K.27: "Bonding configurations and earthing inside a telecommunication
building".
[i.2] CENELEC EN 55022: "Information technology equipment - Radio disturbance characteristics -
Limits and methods of measurement".
[i.3] Recommendation ITU-T L.1200: "Specification of DC power feeding system interface".
ETSI
9 ETSI EN 301 605 V1.1.1 (2013-10)
3 Definitions and abbreviations
3.1 Definitions
For the purposes of the present document, the following terms and definitions apply:
3.1.1 IEC definitions
The following definitions (IEC reference in parentheses) with respect to earthing and bonding are introduced by the
IEC 60050 [5] and are used within the present document to maintain conformity.
earth (195-01-03): part of the Earth which is in electric contact with an earth electrode and the electric potential of
which is not necessarily equal to zero earthing arrangement
earth electrode (195-02-01): conductive part, which may be embedded in a specific conductive medium, e.g. concrete
or coke, in electric contact with the Earth
earthing conductor (195-02-03): conductor which provides a conductive path, or part of the conductive path, between
a given point in a system or in an installation or in equipment and an earth electrode
earthing network (604-04-07): part of an earthing installation that is restricted to the earth electrodes and their
interconnections
equipotential bonding (195-01-10): provision of electric connections between conductive parts, intended to achieve
equipotentiality
exposed-conductive-part (826-12-10): conductive part of equipment which can be touched and which is not normally
live, but which can become live when basic insulation fails
extraneous-conductive-parts (195-06-11): conductive part not forming part of the electrical installation and liable to
introduce an electric potential, generally the electric potential of a local earth
functional-equipotential-bonding (826-13-21): equipotential bonding for operational reasons other than safety
insulation monitoring device (IMD): an IMD for IT systems defined in HD 60364-series gives a warning if the
insulation resistance R (including the insulation resistance of all the connected appliances) between the system live
F
conductors and earth falls below a predetermined level (response value R ). See EN 61557-8 [13]
a
line conductor (826-14-09): conductor which is energized in normal operation and capable of contributing to the
transmission or distribution of electric energy but which is not a neutral or mid-point conductor
live part (826-12-08): conductor or conductive part intended to be energized in normal operation, including a neutral
conductor, but by convention not a PEN conductor or PEM conductor or PEL conductor
main earthing terminal (826-13-15): terminal or busbar which is part of the earthing arrangement of an installation
and enabling the electric connection of a number of conductors for earthing purposes
mid-point (MP) (826-14-04): common point between two symmetrical circuit elements whose opposite ends are
electrically connected to different line conductors of the same circuit
NOTE: MP is an abbreviation for "mid-point" defined and used in the present document.
mid-point conductor (M) (826-14-08): conductor electrically connected to the mid-point and capable of contributing
to the distribution of electric energy
neutral conductor (N) (826-01-03): conductor connected to the neutral point of a system and capable of contributing to
the transmission of electrical energy
PEL conductor (826-13-27): conductor combining the functions of both a protective earthing conductor and a line
conductor
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10 ETSI EN 301 605 V1.1.1 (2013-10)
PEM conductor (826-13-26): conductor combining the functions of both a protective earthing conductor and a
mid-point conductor
PEN conductor (826-13-25): conductor combining the functions of both a protective earthing conductor and a neutral
conductor
protective bonding conductor (195-02-10): protective conductor provided for protective-equipotential-bonding
protective earthing conductor (PE) (826-13-23): protective conductor provided for protective earthing
protective-equipotential-bonding (826-13-20): equipotential bonding for the purposes of safety
residual current device (RCD) (442-05-02): mechanical switching device designed to make, carry and break currents
under normal service conditions and to cause the opening of the contacts when the residual current attains a given value
under specified conditions
IT, TN-C, TN-S, and TT systems (see HD 60364-1 [2]): The codes used have the following meanings:
First letter – Relationship of the power system to earth:
T = direct connection of one point to earth;
I = all live parts isolated from earth, or one point connected to earth through a high impedance.
Second letter – Relationship of the exposed-conductive-parts of the installation to earth:
T = direct electrical connection of exposed-conductive-parts to earth, independently of the earthing of any point of the
power system;
N = direct electrical connection of the exposed-conductive-parts to the earthed point of the power system
Subsequent letter(s) (if any) – Arrangement of neutral and protective conductors:
S = protective function provided by a conductor separate from the neutral conductor or from the earthed line conductor.
C = neutral and protective functions combined in a single conductor (PEN conductor).
3.1.2 Other definitions
The following definitions, specific to telecommunication installations and not covered by the IEC 60050 [5], are used
within the present document. Correspondence to Recommendation ITU-T K.27 [i.1] and ETSI are indicated where
appropriate.
bonding mat: essential means to provide a SRPP by a discernible, nearly regular mesh structure
NOTE: The bonding mat may be located either below or above a collection of equipment constituting a system
block.
Bonding Network (BN), (Recommendation ITU-T K.27 [i.1]): set of interconnected conductive structures that
provides an "electromagnetic shield" for electronic systems and personnel at frequencies from Direct Current (DC) to
low Radio Frequency (RF)
NOTE: The term "electromagnetic shield" denotes any structure used to divert, block or impede the passage of
electromagnetic energy. In general, a BN need not be connected to earth but all BNs considered in the
present document will have an earth connection.
Common Bonding Network (CBN), (Recommendation ITU-T K.27 [i.1]): principal means for effective bonding and
earthing inside a telecommunication building
NOTE: It is the set of metallic components that are intentionally or incidentally interconnected to form the
principal BN in a building. These components include: structural steel or reinforcing rods, metallic
plumbing, Alternating Current (AC) power conduit, PE conductors, cable racks and bonding conductors.
The CBN always has a mesh topology and is connected to the earthing network.
DC return conductor: (L-) conductor of the +400 VDC secondary DC supply and (L+) conductor of the -48 V or
-60 V secondary DC supply
NOTE: The DC conductor may or may not be connected to earth.
Isolated Bonding Network (IBN): bonding network that has a single point of connection ("SPC") to either the
common bonding network or another isolated bonding network
NOTE: All IBNs considered here will have a connection to earth via the SPC.
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11 ETSI EN 301 605 V1.1.1 (2013-10)
ICT equipment: equipment designed for Information and Communication Technologies
NOTE: It is similar to Information Technology (IT), but focuses primarily on communication technologies. This
includes the Internet, wireless networks, cell phones, and other communication mediums.
MESHed Bonding Network (MESH-BN), (Recommendation ITU-T K.27 [i.1]): bonding network in which all
associated equipment frames, racks and cabinets and usually the DC power return conductor, are bonded together as
well as at multiple points to the CBN
NOTE 1: Consequently, the MESH-BN augments the CBN.
NOTE 2: See Figure 1 of the present document.
MESHed Isolated Bonding Network (MESH-IBN), (Recommendation ITU-T K.27 [i.1]): type of IBN in which the
components of the IBN (e.g. equipment frames) are interconnected to form a mesh-like structure
NOTE: This may, for example, be achieved by multiple interconnections between cabinet rows, or by connecting
all equipment frames to a metallic grid (a "bonding mat") extending beneath the equipment. The bonding
mat is, of course, insulated from the adjacent CBN. If necessary the bonding mat could include vertical
extensions, resulting in an approximation to a Faraday cage. The spacing of the grid is chosen according
to the frequency range of the electromagnetic environment.
normal service voltage range: range of the steady-state voltage at the A3 interface over which the equipment will
maintain normal service
NOTE: A3 as defined in EN 300 132-3-1 [1].
power supply:
- primary supply: public mains or, under emergency conditions, a locally generated AC supply
- secondary supply: supply to the ICT equipment, racks or system block, derived from the primary supply
- tertiary supplies: supplies to the ICT equipment, derived from the secondary supply
system: regularly interacting or interdependent group of items forming a unified whole
system block: functional group of equipment depending in its operation and performance on its connection to the same
system reference potential plane, inherent to a MESH-BN
System Reference Potential Plane (SRPP): conductive solid plane, as an ideal goal in potential equalizing, is
approached in practice by horizontal or vertical meshes
NOTE 1: The mesh width thereof is adapted to the frequency range to be considered. Horizontal and vertical
meshes may be interconnected to form a grid structure approximating to a Faraday cage.
NOTE 2: The SRPP facilitates signalling with reference to a common potential.
3.2 Abbreviations
For the purposes of the present document, the following abbreviations apply:
AC Alternating Current
BN Bonding Network
BTS Base Transceiver Station
CB Circuit Breaker
CBN Common Bonding Network
CM Common Mode
DC Direct Current
DC-C Common DC return (2-wire)
DC-I Isolated DC return (3-wire)
EMC ElectroMagnetic Compatibility
IBN Isolated Bonding Network
ICT Information and Communication Technology
IEC International Electrotechnical Commission
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12 ETSI EN 301 605 V1.1.1 (2013-10)
IMD Insulation Monitoring Device
IT See clause 3.1.1.
ITU-T International Telecommunication Union-Telecommunication
LPS Lightning Protection System
M Mid-point conductor
MESH-BN MESHed Bonding Network
MESH-IBN MESHed Isolated Bonding Network
MET Main Earthing Terminal
MP Mid-Point
N Neutral conductor
PE Protective Earthing conductor
PEL combined Protective Earthing conductor and Line conductor
PELV Protective Extra Low Voltage
PEM combined Protective Earthing conductor and Mid-point conductor
PEN combined Protective Earthing conductor and Neutral conductor
RCD Residual Current Device
RF Radio Frequency
SELV Safety Extra Low Voltage
SRPP System Reference Potential Plane
TN See clause 3.1.1.
TN-C See clause 3.1.1.
TN-S See clause 3.1.1.
TT See clause 3.1.1.
VAC Volts Alternating Current
VDC Volts Direct Current
4 General requirements
The earthing and bonding arrangements for 400 VDC interface A3 (stipulated in EN 300 132-3-1 [1]) treated in the
present document are intended to be implemented on new sites as well as on existing sites.
NOTE 1: The interface A3 is equivalent to the interface P in Recommendation ITU-T L.1200 [i.3].
The earthing and bonding arrangements for 400 VDC interface A3 are intended to co-exist with the earthing and
bonding arrangements according to EN 300 253 [9] valid for -48 VDC interface A and according to EN 50310 [8] valid
for ICT equipment powered by 230 VAC, without any adverse effects on safety and continuity of service.
NOTE 2: If no specific voltage is stated in connection to expressions like "ICT equipment", "ICT system", etc. in
the text below, the normal service voltage range for interface A3 is presumed as defined in
EN 300 132-3-1 [1].
4.1 Safety from electrical hazards
HD 60364-series of standards lay down the rules for the design, erection, and verification of electrical installations.
These standards shall be complied with to provide for safety of persons and property against dangers and damage which
may arise in the electrical installations and to provide for the proper functioning of those installations.
The installation material involved shall provide sufficiently high voltage, current, temperature ratings according to the
relevant safety standards to avoid electric shock, risk of fire, or damage to the equipment under normal or faulty
operating conditions within an equipment or the distribution network, or due to the impact of induced voltage and
current, e.g. by lightning.
The design of ICT equipment shall meet relevant product standard such as EN 60950-1 [6] and EN 41003 [10].
• For safety reasons all exposed-conductive-parts (e.g. equipment chassis) of 400 VDC ICT equipment (class I)
shall be provided with a protective earthing conductor (PE).
Class II equipment with conductive chassis shall either be galvanically isolated from the chassis of class I equipment or
be provided with a protective earthing conductor (PE). For these reasons only ICT equipment of type "class I" are
recommended and presumed for the earthing arrangement presented in the present document.
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13 ETSI EN 301 605 V1.1.1 (2013-10)
The conductors involved shall provide sufficiently high current conducting capability and low impedance according to
the relevant safety standards to avoid electric shock, risk of fire, or damage to the equipment under normal or faulty
operating conditions within an equipment or the distribution network, or due to the impact of induced voltage and
current, e.g. by lightning. See references HD 60364-5-54 [4] and EN 50174-2 [12].
4.2 Signal reference
Reliable signal reference shall be provided by a SRPP dedicated at least to a functional unit or a system block. To avoid
undue functional distortion or risk of component failure, the SRPP shall provide sufficiently low impedance up to the
highest frequency to be regarded by using a metal plane or a meshed configuration having adequate mesh dimensions,
e.g. a bonding mat. The frequency band to be covered shall include the spectral components of transients caused by
switching, short circuits and atmospheric discharges.
NOTE: Signal reference to the SRPP does not always imply signal return via the SRPP.
4.3 EMC performance
Measures to gain a satisfactory EMC performance shall be assisted by a SRPP. The SRPP shall provide sufficiently low
impedance for efficient connection of filters, cabinets and cable shields. The requirement to avoid undue emission of or
susceptibility to electromagnetic energy under normal operating conditions may govern the properties of the SRPP
ahead of what is required in clause 4.2. The EMC requirements addressed include the discharge of electrostatic energy.
NOTE: Relevant safety standards allow a class I equipment to have Y-capacitors as decoupling capacitance from
the line and neutral conductor respectively to exposed conductive parts. Due to this fact class I equipment
is normally much easier to comply with the class B EMC requirements. See reference EN 55022 [i.2].
5 Requirements on bonding networks
5.1 Bonding configurations
Bonding configurations can be addressed at a building level (i.e. CBN), at an installation level (i.e. merging of CBN and
MESHed Bonding Network (MESH-BN)) and at an equipment level (i.e. MESH-BN).
Recommendation ITU-T K.27 [i.1] deals with bonding configurations of -48 VDC powered telecommunication
equipment. Bonding configuration for 400 VDC at equipment, installation and building level shall explicitly be
implemented as MESH-BN according to the directives in the present document.
NOTE: Other earthing topologies than MESH-BN are not in the scope of the present document, but are covered
in Recommendation ITU-T K.27 [i.1], such as Star-IBN and MESH-IBN, which sometimes are
implemented.
5.2 CBN within a building for data and telecom centres
Each building for telecom and data centres shall be provided with a CBN having sufficiently low impedance and high
current conducting capability to meet the general requirements of clause 4.
The earthing conductor and the equipotential bonding conductors should be coloured in accordance to international and
national regulations.
The main earthing terminal of the CBN shall be extended by a bonding ring conductor along the inside perimeter of the
building. As a basic element of the CBN, a ring conductor shall at least comprise the system block by its outer
perimeter. An extension of the ICT equipment installation inside a building requires to augment such a minimum CBN
version into a three dimensional grid structure, approximating a Faraday cage (see Figure 1). The impact of interfering
energy in an exposed location or the need for information security enforces the provision of shielded rooms as a
maximum requirement to the CBN.
For further details about earthing and bonding arrangement in buildings refer to the publication HD 60364-5-54 [4].
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14 ETSI EN 301 605 V1.1.1 (2013-10)
Annex A gives information about the implementation principles for the CBN, thereby following Recommendation
ITU-T K.27 [i.1], clause 4.2.1.
5.3 BN within a data and telecom centre
Within a system block of ICT equipment and between different system blocks, the BN shall be of the mesh type. The
MESH-BN shall provide sufficiently low impedance and high current conducting capability to meet the general
requirements in clause 4.
The MESH-BN shall interconnect shelves, cabinets, rack rows, cable racks, ducts, distribution frames, cable shields and
bonding mat to constitute the required SRPP.
All metallic parts of the MESH-BN shall form an electrically continuous whole. This does not necessarily require
bonding by additional bonding straps, but that improvements should be taken into account when determining the
finishes and fastening methods to be used. The mechanical structure comprised by the MESH-BN shall form part of the
SRPP.
As an example, Figure 1 addresses interconnections within a system block, essential to a MESH-BN. This example
follows the implementation principles for the MESH-BN outlined in Recommendation ITU-T K.27 [i.1], clause 4.2.2.
The cable shields shall be connected to the rack.
NOTE 1: With reference to Figure 1:
The live conductors:
� -48 VDC in the "-48 VDC box"
� +400 VDC in the "+400 VDC box"
� +200 VDC and -200 VDC respectively in the "±200 VDC box"
are not routed in the figure, only return-conductors (0 VDC) and protective earth (PE).
NOTE 2: With reference to Figure 1:
� The positive pole (L+) is earthed in the "-48 VDC box", while the negative pole (L-) is earthed in
the " +400 VDC box" (see clause 6.1.2.2).
ETSI
15 ETSI EN 301 605 V1.1.1 (2013-10)
L+L+L+
L-L-L-
2-2-wwiirree
3-3-wwiirree
OpOpttioionnaall
ifif Mes Meshh--BBNN//CCBBNN
EaEarthrtheedd
hhiigghh--ohmohmiicc
MPMP
mimidd--ppooiinnt t
teterrmmiinnaall
±±200200 Vd Vdcc ++400 V400 Vddcc -4-488 V Vddcc
ITIT TTNN--SS
++440000 V Vddcc re retuturn (0rn (0 VVddc)c)
-48-48 V Vddcc ret retuurnrn (0 (0 V Vddcc))
PPrrootteeccttiivvee Ea Earrtthh ((PPE)E)
IInntetercrcononnenectcteded re reiinnffoorcrcememeenntt
anand bud buiilldidinngg sstteeelel
InInttrra-a-sysysstteemm ca cablbliinngg
SShhieieldldeedd in intteerr--ssyysstteemm ccaabblinlingg
BBoonnddiinng cog condnducuctotorr
Figure 1: Example of a CBN/MESH-BN installation inside a telecommunication building
ETSI
16 ETSI EN 301 605 V1.1.1 (2013-10)
5.4 Merging of CBN and MESH-BNs
All BNs of ICT systems and their associated protective earthing conductors shall be connected to the CBN.
The MESH-BN shall augment the CBN including the main earthing terminal by multiple interconnections to the CBN
(see Figure 1).
5.5 Cabling within and between BNs
Power distribution cables and signal cables within and between MESH-BNs shall be run tightly along the members of
the augmented CBN.
There shall be a separation distance of at least 100 mm between groups of AC mains cables and groups of signal cables
on one and the same cable rack, unless adequate shielding is provided.
Cable shields shall be bonded directly to racks, cabinets or to the dedicated SRPP at least at each end. Circumferential
connections are most effective and therefore are recommended.
NOTE: It is recognized that where a new system has to be cabled to existing equipment, it has previously been
considered feasible to avoid the connection of cable shields at the existing equipment end. However, the
consequent solution of the present document is to provide a lower impedance path via improved bonding
between the equipment locations, thereby enabling connection of cable shields at least at each end.
6 Requirements for power distribution
6.1 DC power distribution of secondary supply
6.1.1 General
The DC power distribution shall route line conductors close together. Live parts, including each line conductor (L+ and
L-) shall be completely covered with insulation which can only be removed by destruction. The insulation is intended to
prevent contact with live parts.
The laying of the DC power distribution shall comply with relevant installation standards concerning voltage rating,
ambient temperature and current carrying capacity of the cables.
The ICT equipment shall comply with the relevant product standard.
Exposed-conductive-parts shall be connected to a protective earthing conductor (PE) under the specific conditions for
each type of system earthing as specified below in clause 6.1.2.
The line conductor and the protective earthing conductor shall be capable of carrying over-currents in the case of a fault
between a line conductor of the 400 VDC secondary supply and the MESH-BN. See HD 60364-5-54 [4].
Simultaneously accessible exposed-conductive-parts shall be collectively earthed to the same earthing system of which
the MESH-BN is an integral part.
6.1.2 System earthing arrangement
The definitions used in this clause are based on HD 60364-1 [2].
The DC power distribution of the secondary supply serving the ICT system shall conform to the requirements of the IT
or TN-S system.
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17 ETSI EN 301 605 V1.1.1 (2013-10)
6.1.2.1 IT system with earthed high-ohmic mid-point (MP) terminal
Figure 2 shows a preferred symmetrical IT system earthing arrangement for 400 VDC. This arrangement is based on
the IT system earthing type b) according to HD 60364-1 [2] (see Figure D.2 in Annex D of the present document) but
modified for adaptation to one 400 V power source instead of a series connection of two 200 V power sources.
NOTE 1: Figure 2 is based on figure 31M – IT d.c. system, Type a) from IEC 60364-1 [2] and modified to a IT
system with an earthed high-ohmic mid-point terminal (MP).
The high-ohmic mid-point terminal (MP) of the power plant powering the ICT equipment shall be connected to the
Main Earthing Terminal (MET) for functional reasons.
The high-ohmic mid-point terminal (MP) is the common point between two symmetrical high-ohmic resistors
(typically > 50 kΩ ) whose opposite ends are electrically connected to the different line conductors (L+ and L-) of the
same circuit.
In cases where an IT system is used for reasons of continuity of supply, automatic disconnection is not usually required
on the occurrence of a first fault (single fault) to an exposed-conductive-part or to earth. This is valid on condition that
an insulation monitoring device (IMD) indicates the first fault by an audible and/or visual signal which shall continue as
long as the fault persists. See further requirements in Annex B.
After the occurrence of a first fault, conditions for automatic disconnection of supply in the event of a second fault
occurring on a different live conductor shall be as stipulated in normative clause B.1.2.
1)
The dotted lines have the same implication as in HD 60364-1, 312.2, Note 2, that is:
If connected to earth via sufficiently high impedance, this additional earthing is for functional reasons only
and not part of or a replacement of the protective measures stipulated in
...
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Okoljski inženiring (EE) - Ozemljitev in spajanje 400 VDC podatkovne in telekomunikacijske (IKT) opremeEnvironmental Engineering (EE) - Earthing and bonding of 400 VDC data and telecom (ICT) equipment33.050.01Telekomunikacijska terminalska oprema na splošnoTelecommunication terminal equipment in general19.040Preskušanje v zvezi z okoljemEnvironmental testingICS:Ta slovenski standard je istoveten z:EN 301 605 Version 1.1.1SIST EN 301 605 V1.1.1:2013en01-december-2013SIST EN 301 605 V1.1.1:2013SLOVENSKI
STANDARD
European Standard SIST EN 301 605 V1.1.1:2013
ETSI ETSI EN 301 605 V1.1.1 (2013-10) 2
Reference DEN/EE-02045 Keywords bonding, earthing, power ETSI 650 Route des Lucioles F-06921 Sophia Antipolis Cedex - FRANCE
Tel.: +33 4 92 94 42 00
Fax: +33 4 93 65 47 16
Siret N° 348 623 562 00017 - NAF 742 C Association à but non lucratif enregistrée à la Sous-Préfecture de Grasse (06) N° 7803/88
Important notice Individual copies of the present document can be downloaded from: http://www.etsi.org The present document may be made available in more than one electronic version or in print. In any case of existing or perceived difference in contents between such versions, the reference version is the Portable Document Format (PDF). In case of dispute, the reference shall be the printing on ETSI printers of the PDF version kept on a specific network drive within ETSI Secretariat. Users of the present document should be aware that the document may be subject to revision or change of status. Information on the current status of this and other ETSI documents is available at http://portal.etsi.org/tb/status/status.asp If you find errors in the present document, please send your comment to one of the following services: http://portal.etsi.org/chaircor/ETSI_support.asp Copyright Notification No part may be reproduced except as authorized by written permission. The copyright and the foregoing restriction extend to reproduction in all media.
© European Telecommunications Standards Institute 2013. All rights reserved.
DECTTM, PLUGTESTSTM, UMTSTM and the ETSI logo are Trade Marks of ETSI registered for the benefit of its Members. 3GPPTM and LTE™ are Trade Marks of ETSI registered for the benefit of its Members and of the 3GPP Organizational Partners. GSM® and the GSM logo are Trade Marks registered and owned by the GSM Association. SIST EN 301 605 V1.1.1:2013
ETSI ETSI EN 301 605 V1.1.1 (2013-10) 3 Contents Intellectual Property Rights . 5 Foreword . 5 Introduction . 6 1 Scope . 7 2 References . 7 2.1 Normative references . 7 2.2 Informative references . 8 3 Definitions and abbreviations . 9 3.1 Definitions . 9 3.1.1 IEC definitions . 9 3.1.2 Other definitions . 10 3.2 Abbreviations . 11 4 General requirements . 12 4.1 Safety from electrical hazards . 12 4.2 Signal reference . 13 4.3 EMC performance . 13 5 Requirements on bonding networks . 13 5.1 Bonding configurations . 13 5.2 CBN within a building for data and telecom centres . 13 5.3 BN within a data and telecom centre . 14 5.4 Merging of CBN and MESH-BNs . 16 5.5 Cabling within and between BNs . 16 6 Requirements for power distribution . 16 6.1 DC power distribution of secondary supply . 16 6.1.1 General . 16 6.1.2 System earthing arrangement . 16 6.1.2.1 IT system with earthed high-ohmic mid-point (MP) terminal . 17 6.1.2.2 TN-S system with earthed negative line terminal (L-) . 18 6.2 DC power distribution of tertiary supplies . 19 6.3 AC mains distribution and bonding of the protective conductor . 20 6.4 AC power distribution from tertiary power supply . 20 Annex A (normative): Rationale about CBN co-ordination . 21 Annex B (normative): Requirements for fault protection . 22 B.1 Protective earthing . 22 B.1.1 TN and TT System Earthing. 22 B.1.2 IT System Earthing . 22 B.1.2.1 First fault on one of the live conductors . 22 B.1.2.2 Second fault on a different live conductor . 23 B.2 Protective equipotential bonding . 24 Annex C (informative): Coexistence of -48 VDC/-60 VDC DC-C (2-wire) and 400 VDC class I equipment in MESH-BN . 25 Annex D (informative): Conductor arrangement and system earthing . 27 D.1 General remarks . 30 D.2 Ease of earth fault detection with high ohmic mid-point . 31 D.2.1 IT system with (L-) earthed via high impedance . 31 D.2.2 IT system with earthed high-ohmic mid-point (MP) terminal . 31 SIST EN 301 605 V1.1.1:2013
ETSI ETSI EN 301 605 V1.1.1 (2013-10) 4 D.3 Impact on body current due to a large number of loads . 32 Annex E (normative): AC mains distribution and bonding of the protective conductor . 34 Annex F (normative): Basic protection and Fault protection . 37 F.1 Basic protection (protection against direct contact) . 37 F.1.1 Basic insulation of live parts . 37 F.2 Fault protection (protection against indirect contact) . 37 F.2.1 Automatic disconnection in case of a fault . 37 F.3 Conclusions . 38 Annex G (informative): Bibliography . 39 History . 40
ETSI ETSI EN 301 605 V1.1.1 (2013-10) 5 Intellectual Property Rights IPRs essential or potentially essential to the present document may have been declared to ETSI. The information pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web server (http://ipr.etsi.org). Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web server) which are, or may be, or may become, essential to the present document. Foreword This European Standard (EN) has been produced by ETSI Technical Committee Environmental Engineering (EE). The present document has been produced within the framework of the following considerations: a) Datacommunications and Telecommunications (ICT) equipment is generally installed in data and telecom centres and held in racks, cabinets or other mechanical structures; b) the existing ITU-T and ITU-R Recommendations and CENELEC standards in such matters do not ensure the required standardization at the equipment level; c) network operators and equipment providers agreed to standardize on a bonding configuration that facilitates: - compliance with functional requirements including Electromagnetic Compatibility (EMC) aspects of emission and immunity; - compatible building and equipment provisions; - installation of new data and telecom centres as well as expansion or replacement of installations in existing data and telecom centres with equipment coming from different suppliers; - a structured installation practice; - simple maintenance rules; - contracting on a common basis; - cost effectiveness in development, manufacturing, installation and operation.
National transposition dates Date of adoption of this EN: 30 September 2013 Date of latest announcement of this EN (doa): 31 December 2013 Date of latest publication of new National Standard or endorsement of this EN (dop/e):
30 June 2014 Date of withdrawal of any conflicting National Standard (dow): 30 June 2014
ETSI ETSI EN 301 605 V1.1.1 (2013-10) 6 Introduction The present document addresses earthing and bonding of data and telecom (ICT) equipment in data and telecom centres when implementing a direct current interface up to 400 VDC defined in EN 300 132-3-1 [1] in relation to safety, functional performance and EMC. The present standard may also be applicable for ICT equipment in other locations such as: street cabinets, containers, subscriber's buildings, BTSs, etc. The general principles for electrical installations from a safety perspective are based on the HD 60364-series
(IEC 60364-series) of standards, and where appropriate on information published by ITU-T to provide for the proper functioning of those installations. The author thanks the International Electrotechnical Commission (IEC) for permission to reproduce Information from its International Standard IEC 60364-1 ed. 5.0 (2005). All such extracts are copyright of IEC, Geneva, Switzerland. All rights reserved. Further information on the IEC is available from www.iec.ch/. IEC has no responsibility for the placement and context in which the extracts and contents are reproduced by the author, nor is IEC in any way responsible for the other content or accuracy therein. SIST EN 301 605 V1.1.1:2013
ETSI ETSI EN 301 605 V1.1.1 (2013-10) 7 1 Scope The present document applies to earthing and bonding of ICT equipment installed in data and telecom centres and similar installations operating within the normal service voltage range up to 400 VDC defined in EN 300 132-3-1 [1]. Earthing and bonding network of the building (CBN), the bonding network of the equipment (SRPP), and the interconnection between these two networks are treated in the present document. It contributes to the standardization of telecommunication and datacom equipment installation. It also co-ordinates with the pre-conditions of the installation to achieve the following targets: • safety from electrical hazards; • continuity of service requiring: - reliable signal reference; - satisfactory Electromagnetic Compatibility (EMC) performance. The present document defines earthing and bonding configuration down to the equipment level in order to facilitate the installation, operation and maintenance of data and telecom centres in data and telecom buildings or similar installations independent of the equipment supplier. The specification of ICT equipment and of the pre-conditions of installation is subject to agreement of the parties (e.g. the supplier and the purchaser). Annex A can be used in the procedure to achieve an agreement. The present document does not cover safety and EMC aspects of the equipment. Those aspects are covered by other relevant standards.
The present document applies to the installation of ICT equipment in data and telecom centres. The present document may also be applicable for ICT equipment in other locations, e.g.: • street cabinet; • container; • subscriber's building; • BTS. 2 References References are either specific (identified by date of publication and/or edition number or version number) or non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the referenced document (including any amendments) applies. Referenced documents which are not found to be publicly available in the expected location might be found at http://docbox.etsi.org/Reference. NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee their long term validity. 2.1 Normative references The following referenced documents are necessary for the application of the present document. [1] ETSI EN 300 132-3-1: "Environmental Engineering (EE); Power supply interface at the input to telecommunications and datacom (ICT) equipment; Part 3: Operated by rectified current source, alternating current source or direct current source up to 400 V; Sub-part 1: Direct current source up to 400 V". SIST EN 301 605 V1.1.1:2013
ETSI ETSI EN 301 605 V1.1.1 (2013-10) 8 [2] CENELEC HD 60364-1: "Low-voltage electrical installations - Part 1: Fundamental principles, assessment of general characteristics, definitions" (IEC 60364-1). [3] CENELEC HD 60364-4-41: "Low-voltage electrical installations - Part 4-41: Protection for safety - Protection against electric shock" (IEC 60364-4-41). [4] CENELEC HD 60364-5-54: "Low-voltage electrical installations - Part 5-54: Selection and erection of electrical equipment - Earthing arrangements and protective conductors"
(IEC 60364-5-54). [5] IEC 60050: "International Electrotechnical Vocabulary". [6] CENELEC EN 60950-1: "Information technology equipment - Safety - Part 1: General requirements" (IEC 60950-1). [7] CENELEC EN 62305-series: "Protection against lightning" (IEC 62305-series). [8] CENELEC EN 50310: "Application of equipotential bonding and earthing in buildings with information technology equipment". [9] ETSI EN 300 253: "Environmental Engineering (EE); Earthing and bonding of telecommunication equipment in telecommunication centres". [10] CENELEC EN 41003: "Particular safety requirements for equipment to be connected to telecommunication networks and/or a cable distribution system". [11] IEC/TR 60479-5: "Effects of current on human beings and livestock - Part 5: Touch voltage threshold values for physiological effects". [12] CENELEC EN 50174-2: "Information technology -Cabling installation -Part 2: Installation planning and practices inside buildings". [13] CENELEC EN 61557-8: "Electrical safety in low voltage distribution systems up to 1 000 V a.c. and 1 500 V d.c. - Equipment for testing, measuring or monitoring of protective measures - Part 8: Insulation monitoring devices for IT systems" (IEC 61557-8). [14] CENELEC EN 61557-9: "Electrical safety in low voltage distribution systems up to 1 000 V a.c. and 1 500 V d.c. - Equipment for testing, measuring or monitoring of protective measures - Part 9: Equipment for insulation fault location in IT systems" (IEC 61557-9). [15] CENELEC HD 308: "Identification of cores in cables and flexible cords". [16] CENELEC EN 60445: "Basic and safety principles for man-machine interface, marking and identification - Identification of equipment terminals, conductor terminations and conductors" (IEC 60445). 2.2 Informative references The following referenced documents are not necessary for the application of the present document but they assist the user with regard to a particular subject area. [i.1] Recommendation ITU-T K.27: "Bonding configurations and earthing inside a telecommunication building". [i.2] CENELEC EN 55022: "Information technology equipment - Radio disturbance characteristics - Limits and methods of measurement". [i.3] Recommendation ITU-T L.1200: "Specification of DC power feeding system interface". SIST EN 301 605 V1.1.1:2013
ETSI ETSI EN 301 605 V1.1.1 (2013-10) 9 3 Definitions and abbreviations 3.1 Definitions For the purposes of the present document, the following terms and definitions apply: 3.1.1 IEC definitions The following definitions (IEC reference in parentheses) with respect to earthing and bonding are introduced by the IEC 60050 [5] and are used within the present document to maintain conformity. earth (195-01-03): part of the Earth which is in electric contact with an earth electrode and the electric potential of which is not necessarily equal to zero earthing arrangement earth electrode (195-02-01): conductive part, which may be embedded in a specific conductive medium, e.g. concrete or coke, in electric contact with the Earth earthing conductor (195-02-03): conductor which provides a conductive path, or part of the conductive path, between a given point in a system or in an installation or in equipment and an earth electrode earthing network (604-04-07): part of an earthing installation that is restricted to the earth electrodes and their interconnections equipotential bonding (195-01-10): provision of electric connections between conductive parts, intended to achieve equipotentiality exposed-conductive-part (826-12-10): conductive part of equipment which can be touched and which is not normally live, but which can become live when basic insulation fails extraneous-conductive-parts (195-06-11): conductive part not forming part of the electrical installation and liable to introduce an electric potential, generally the electric potential of a local earth functional-equipotential-bonding (826-13-21): equipotential bonding for operational reasons other than safety insulation monitoring device (IMD): an IMD for IT systems defined in HD 60364-series gives a warning if the insulation resistance RF (including the insulation resistance of all the connected appliances) between the system live conductors and earth falls below a predetermined level (response value Ra). See EN 61557-8 [13] line conductor (826-14-09): conductor which is energized in normal operation and capable of contributing to the transmission or distribution of electric energy but which is not a neutral or mid-point conductor live part (826-12-08): conductor or conductive part intended to be energized in normal operation, including a neutral conductor, but by convention not a PEN conductor or PEM conductor or PEL conductor main earthing terminal (826-13-15): terminal or busbar which is part of the earthing arrangement of an installation and enabling the electric connection of a number of conductors for earthing purposes mid-point (MP) (826-14-04): common point between two symmetrical circuit elements whose opposite ends are electrically connected to different line conductors of the same circuit NOTE: MP is an abbreviation for "mid-point" defined and used in the present document. mid-point conductor (M) (826-14-08): conductor electrically connected to the mid-point and capable of contributing to the distribution of electric energy neutral conductor (N) (826-01-03): conductor connected to the neutral point of a system and capable of contributing to the transmission of electrical energy PEL conductor (826-13-27): conductor combining the functions of both a protective earthing conductor and a line conductor SIST EN 301 605 V1.1.1:2013
ETSI ETSI EN 301 605 V1.1.1 (2013-10) 10 PEM conductor (826-13-26): conductor combining the functions of both a protective earthing conductor and a
mid-point conductor PEN conductor (826-13-25): conductor combining the functions of both a protective earthing conductor and a neutral conductor protective bonding conductor (195-02-10): protective conductor provided for protective-equipotential-bonding protective earthing conductor (PE) (826-13-23): protective conductor provided for protective earthing protective-equipotential-bonding (826-13-20): equipotential bonding for the purposes of safety
residual current device (RCD) (442-05-02): mechanical switching device designed to make, carry and break currents under normal service conditions and to cause the opening of the contacts when the residual current attains a given value under specified conditions IT, TN-C, TN-S, and TT systems (see HD 60364-1 [2]): The codes used have the following meanings: First letter – Relationship of the power system to earth: T = direct connection of one point to earth; I = all live parts isolated from earth, or one point connected to earth through a high impedance. Second letter – Relationship of the exposed-conductive-parts of the installation to earth: T = direct electrical connection of exposed-conductive-parts to earth, independently of the earthing of any point of the power system; N = direct electrical connection of the exposed-conductive-parts to the earthed point of the power system
Subsequent letter(s) (if any) – Arrangement of neutral and protective conductors: S = protective function provided by a conductor separate from the neutral conductor or from the earthed line conductor. C = neutral and protective functions combined in a single conductor (PEN conductor). 3.1.2 Other definitions The following definitions, specific to telecommunication installations and not covered by the IEC 60050 [5], are used within the present document. Correspondence to Recommendation ITU-T K.27 [i.1] and ETSI are indicated where appropriate. bonding mat: essential means to provide a SRPP by a discernible, nearly regular mesh structure NOTE: The bonding mat may be located either below or above a collection of equipment constituting a system block. Bonding Network (BN), (Recommendation ITU-T K.27 [i.1]): set of interconnected conductive structures that provides an "electromagnetic shield" for electronic systems and personnel at frequencies from Direct Current (DC) to low Radio Frequency (RF) NOTE: The term "electromagnetic shield" denotes any structure used to divert, block or impede the passage of electromagnetic energy. In general, a BN need not be connected to earth but all BNs considered in the present document will have an earth connection. Common Bonding Network (CBN), (Recommendation ITU-T K.27 [i.1]): principal means for effective bonding and earthing inside a telecommunication building NOTE: It is the set of metallic components that are intentionally or incidentally interconnected to form the principal BN in a building. These components include: structural steel or reinforcing rods, metallic plumbing, Alternating Current (AC) power conduit, PE conductors, cable racks and bonding conductors. The CBN always has a mesh topology and is connected to the earthing network. DC return conductor: (L-) conductor of the +400 VDC secondary DC supply and (L+) conductor of the -48 V or -60 V secondary DC supply NOTE: The DC conductor may or may not be connected to earth. Isolated Bonding Network (IBN): bonding network that has a single point of connection ("SPC") to either the common bonding network or another isolated bonding network NOTE: All IBNs considered here will have a connection to earth via the SPC. SIST EN 301 605 V1.1.1:2013
ETSI ETSI EN 301 605 V1.1.1 (2013-10) 11 ICT equipment: equipment designed for Information and Communication Technologies NOTE: It is similar to Information Technology (IT), but focuses primarily on communication technologies. This includes the Internet, wireless networks, cell phones, and other communication mediums. MESHed Bonding Network (MESH-BN), (Recommendation ITU-T K.27 [i.1]): bonding network in which all associated equipment frames, racks and cabinets and usually the DC power return conductor, are bonded together as well as at multiple points to the CBN NOTE 1: Consequently, the MESH-BN augments the CBN. NOTE 2: See Figure 1 of the present document. MESHed Isolated Bonding Network (MESH-IBN), (Recommendation ITU-T K.27 [i.1]): type of IBN in which the components of the IBN (e.g. equipment frames) are interconnected to form a mesh-like structure NOTE: This may, for example, be achieved by multiple interconnections between cabinet rows, or by connecting all equipment frames to a metallic grid (a "bonding mat") extending beneath the equipment. The bonding mat is, of course, insulated from the adjacent CBN. If necessary the bonding mat could include vertical extensions, resulting in an approximation to a Faraday cage. The spacing of the grid is chosen according to the frequency range of the electromagnetic environment. normal service voltage range: range of the steady-state voltage at the A3 interface over which the equipment will maintain normal service NOTE: A3 as defined in EN 300 132-3-1 [1]. power supply: - primary supply: public mains or, under emergency conditions, a locally generated AC supply - secondary supply: supply to the ICT equipment, racks or system block, derived from the primary supply - tertiary supplies: supplies to the ICT equipment, derived from the secondary supply system: regularly interacting or interdependent group of items forming a unified whole system block: functional group of equipment depending in its operation and performance on its connection to the same system reference potential plane, inherent to a MESH-BN System Reference Potential Plane (SRPP): conductive solid plane, as an ideal goal in potential equalizing, is approached in practice by horizontal or vertical meshes NOTE 1: The mesh width thereof is adapted to the frequency range to be considered. Horizontal and vertical meshes may be interconnected to form a grid structure approximating to a Faraday cage. NOTE 2: The SRPP facilitates signalling with reference to a common potential. 3.2 Abbreviations For the purposes of the present document, the following abbreviations apply: AC Alternating Current BN Bonding Network BTS Base Transceiver Station CB Circuit Breaker CBN Common Bonding Network CM Common Mode DC Direct Current DC-C Common DC return (2-wire) DC-I Isolated DC return (3-wire) EMC ElectroMagnetic Compatibility IBN Isolated Bonding Network ICT Information and Communication Technology IEC International Electrotechnical Commission SIST EN 301 605 V1.1.1:2013
ETSI ETSI EN 301 605 V1.1.1 (2013-10) 12 IMD Insulation Monitoring Device IT See clause 3.1.1. ITU-T International Telecommunication Union-Telecommunication LPS Lightning Protection System M Mid-point conductor MESH-BN MESHed Bonding Network MESH-IBN MESHed Isolated Bonding Network MET Main Earthing Terminal MP Mid-Point N Neutral conductor PE Protective Earthing conductor PEL combined Protective Earthing conductor and Line conductor PELV Protective Extra Low Voltage PEM combined Protective Earthing conductor and Mid-point conductor PEN combined Protective Earthing conductor and Neutral conductor RCD Residual Current Device RF Radio Frequency SELV Safety Extra Low Voltage SRPP System Reference Potential Plane TN See clause 3.1.1. TN-C See clause 3.1.1. TN-S See clause 3.1.1. TT See clause 3.1.1. VAC Volts Alternating Current VDC Volts Direct Current 4 General requirements The earthing and bonding arrangements for 400 VDC interface A3 (stipulated in EN 300 132-3-1 [1]) treated in the present document are intended to be implemented on new sites as well as on existing sites. NOTE 1: The interface A3 is equivalent to the interface P in Recommendation ITU-T L.1200 [i.3].
The earthing and bonding arrangements for 400 VDC interface A3 are intended to co-exist with the earthing and bonding arrangements according to EN 300 253 [9] valid for -48 VDC interface A and according to EN 50310 [8] valid for ICT equipment powered by 230 VAC, without any adverse effects on safety and continuity of service.
NOTE 2: If no specific voltage is stated in connection to expressions like "ICT equipment", "ICT system", etc. in the text below, the normal service voltage range for interface A3 is presumed as defined in
EN 300 132-3-1 [1]. 4.1 Safety from electrical hazards HD 60364-series of standards lay down the rules for the design, erection, and verification of electrical installations. These standards shall be complied with to provide for safety of persons and property against dangers and damage which may arise in the electrical installations and to provide for the proper functioning of those installations. The installation material involved shall provide sufficiently high voltage, current, temperature ratings according to the relevant safety standards to avoid electric shock, risk of fire, or damage to the equipment under normal or faulty operating conditions within an equipment or the distribution network, or due to the impact of induced voltage and current, e.g. by lightning. The design of ICT equipment shall meet relevant product standard such as EN 60950-1 [6] and EN 41003 [10]. • For safety reasons all exposed-conductive-parts (e.g. equipment chassis) of 400 VDC ICT equipment (class I) shall be provided with a protective earthing conductor (PE). Class II equipment with conductive chassis shall either be galvanically isolated from the chassis of class I equipment or be provided with a protective earthing conductor (PE). For these reasons only ICT equipment of type "class I" are recommended and presumed for the earthing arrangement presented in the present document. SIST EN 301 605 V1.1.1:2013
ETSI ETSI EN 301 605 V1.1.1 (2013-10) 13 The conductors involved shall provide sufficiently high current conducting capability and low impedance according to the relevant safety standards to avoid electric shock, risk of fire, or damage to the equipment under normal or faulty operating conditions within an equipment or the distribution network, or due to the impact of induced voltage and current, e.g. by lightning. See references HD 60364-5-54 [4] and EN 50174-2 [12]. 4.2 Signal reference Reliable signal reference shall be provided by a SRPP dedicated at least to a functional unit or a system block. To avoid undue functional distortion or risk of component failure, the SRPP shall provide sufficiently low impedance up to the highest frequency to be regarded by using a metal plane or a meshed configuration having adequate mesh dimensions, e.g. a bonding mat. The frequency band to be covered shall include the spectral components of transients caused by switching, short circuits and atmospheric discharges. NOTE: Signal reference to the SRPP does not always imply signal return via the SRPP. 4.3 EMC performance Measures to gain a satisfactory EMC performance shall be assisted by a SRPP. The SRPP shall provide sufficiently low impedance for efficient connection of filters, cabinets and cable shields. The requirement to avoid undue emission of or susceptibility to electromagnetic energy under normal operating conditions may govern the properties of the SRPP ahead of what is required in clause 4.2. The EMC requirements addressed include the discharge of electrostatic energy. NOTE: Relevant safety standards allow a class I equipment to have Y-capacitors as decoupling capacitance from the line and neutral conductor respectively to exposed conductive parts. Due to this fact class I equipment is normally much easier to comply with the class B EMC requirements. See reference EN 55022 [i.2]. 5 Requirements on bonding networks 5.1 Bonding configurations Bonding configurations can be addressed at a building level (i.e. CBN), at an installation level (i.e. merging of CBN and MESHed Bonding Network (MESH-BN)) and at an equipment level (i.e. MESH-BN). Recommendation ITU-T K.27 [i.1] deals with bonding configurations of -48 VDC powered telecommunication equipment. Bonding configuration for 400 VDC at equipment, installation and building level shall explicitly be implemented as MESH-BN according to the directives in the present document. NOTE: Other earthing topologies than MESH-BN are not in the scope of the present document, but are covered in Recommendation ITU-T K.27 [i.1], such as Star-IBN and MESH-IBN, which sometimes are implemented. 5.2 CBN within a building for data and telecom centres Each building for telecom and data centres shall be provided with a CBN having sufficiently low impedance and high current conducting capability to meet the general requirements of clause 4.
The earthing conductor and the equipotential bonding conductors should be coloured in accordance to international and national regulations. The main earthing terminal of the CBN shall be extended by a bonding ring conductor along the inside perimeter of the building. As a basic element of the CBN, a ring conductor shall at least comprise the system block by its outer perimeter. An extension of the ICT equipment installation inside a building requires to augment such a minimum CBN version into a three dimensional grid structure, approximating a Faraday cage (see Figure 1). The impact of interfering energy in an exposed location or the need for information security enforces the provision of shielded rooms as a maximum requirement to the CBN. For further details about earthing and bonding arrangement in buildings refer to the publication HD 60364-5-54 [4]. SIST EN 301 605 V1.1.1:2013
ETSI ETSI EN 301 605 V1.1.1 (2013-10) 14 Annex A gives information about the implementation principles for the CBN, thereby following Recommendation ITU-T K.27 [i.1], clause 4.2.1. 5.3 BN within a data and telecom centre Within a system block of ICT equipment and between different system blocks, the BN shall be of the mesh type. The MESH-BN shall provide sufficiently low impedance and high current conducting capability to meet the general requirements in clause 4. The MESH-BN shall interconnect shelves, cabinets, rack rows, cable racks, ducts, distribution frames, cable shields and bonding mat to constitute the required SRPP. All metallic parts of the MESH-BN shall form an electrically continuous whole. This does not necessarily require bonding by additional bonding straps, but that improvements should be taken into account when determining the finishes and fastening methods to be used. The mechanical structure comprised by the MESH-BN shall form part of the SRPP. As an example, Figure 1 addresses interconnections within a system block, essential to a MESH-BN. This example follows the implementation principles for the MESH-BN outlined in Recommendation ITU-T K.27 [i.1], clause 4.2.2. The cable shields shall be connected to the rack. NOTE 1: With reference to Figure 1:
The live conductors:
-48 VDC in the "-48 VDC box"
+400 VDC in the "+400 VDC box"
+200 VDC and -200 VDC respectively in the "±200 VDC box" are not routed in the figure, only return-conductors (0 VDC) and protective earth (PE). NOTE 2: With reference to Figure 1:
The positive pole (L+) is earthed in the "-48 VDC box", while the negative pole (L-) is earthed in the " +400 VDC box" (see clause 6.1.2.2). SIST EN 301 605 V1.1.1:2013
ETSI ETSI EN 301 605 V1.1.1 (2013-10) 15 ±200 Vdc+400 Vdc-48 Vdc3-wire2-wireITTN-SIntra-system cablingShielded inter-system cablingBonding conductorInterconnected reinforcementand building steel-48 Vdc return (0 Vdc)+400 Vdc return (0 Vdc)Protective Earth (PE)MPEarthed high-ohmic mid-point terminal Optionalif Mesh-BN/CBNL+L-±200 Vdc+400 Vdc-48 Vdc3-wire2-wireITTN-SIntra-system cablingShielded inter-system cablingBonding conductorInterconnected reinforcementand building steel-48 Vdc return (0 Vdc)+400 Vdc return (0 Vdc)Protective Earth (PE)MPEarthed high-ohmic mid-point terminal Optionalif Mesh-BN/CBNL+L-L+L-
Figure 1: Example of a CBN/MESH-BN installation inside a telecommunication building SIST EN 301 605 V1.1.1:2013
ETSI ETSI EN 301 605 V1.1.1 (2013-10) 16 5.4 Merging of CBN and MESH-BNs All BNs of ICT systems and their associated protective earthing conductors shall be connected to the CBN. The MESH-BN shall augment the CBN including the main earthing terminal by multiple interconnections to the CBN (see Figure 1). 5.5 Cabling within and between BNs Power distribution cables and signal cables within and between MESH-BNs shall be run tightly along the members of the augmented CBN. There shall be a separation distance of at least 100 mm between groups of AC mains cables and groups of signal cables on one and the same cable rack, unless adequate shielding is provided. Cable shields shall be bonded directly to racks, cabinets or to the dedicated SRPP at least at each end. Circumferential connections are most effective and therefore are recommended. NOTE: It is recognized that where a new system has to be cabled to existing equipment, it has previously been considered feasible to avoid the connection of cable shields at the existing equipment end. However, the consequent solution of the present document is to provide a lower impedance path via improved bonding between the equipment locations, thereby enabling connection of cable shields at least at each end. 6 Requirements for power distribution 6.1 DC power distribution of secondary supply 6.1.1 General The DC power distribution shall route line conductors close together. Live parts, including each line conductor (L+ and L-) shall be completely covered with insulation which can only be removed by destruction. The insulation is intended to prevent contact with live parts. The laying of the DC power distribution shall comply with relevant installation standards concerning voltage rating, ambient temperature and current carrying capacity of the cables.
The ICT equipment shall comply with the relevant product standard. Exposed-conductive-parts shall be connected to a protective earthing conductor (PE) under the specific conditions for each type of system earthing as specified below in clause 6.1.2. The line conductor and the protective earthing conductor shall be capable of carrying over-currents in the case of a fault between a line conductor of the 400 VDC secondary supply and the MESH-BN. See HD 60364-5-54 [4]. Simultaneously accessible exposed-conductive-parts shall be collectively earthed to the same earthing system of which the MESH-BN is an integral part. 6.1.2 System earthing arrangement The definitions used in this clause are based on HD 60364-1 [2]. The DC power distribution of the secondary supply serving the ICT system shall conform to the requirements of the IT or TN-S system.
ETSI ETSI EN 301 605 V1.1.1 (2013-10) 17 6.1.2.1 IT system with earthed high-ohmic mid-point (MP) terminal Figure 2 shows a preferred symmetrical IT system earthing arrangement for 400 VDC. This arrangement is based on
the IT system earthing type b) according to HD 60364-1 [2] (see Figure D.2 in Annex D of the present document) but modified for adaptation to one 400 V power source instead of a series connection of two 200 V power sources. NOTE 1: Figure 2 is based on figure 31M – IT d.c. system, Type a) from IEC 60364-1 [2] and modified to a IT system with an earthed high-ohmic mid-point terminal (MP). The high-ohmic mid-point terminal (MP) of the power plant powering the ICT equipment shall be connected to the Main Earthing Terminal (MET) for functional reasons. The high-ohmic mid-point terminal (MP) is the common point between two symmetrical high-ohmic resistors (typically > 50 kΩ ) whose opposite ends are electrically connected to the different line conductors (L+ and L-) of the same circuit. In cases where an IT system is used for reasons of continuity of supply, automatic disconnection is not usually required on the occurrence of a first fault (single fault) to an exposed-conductive-part or to earth. This is valid on condition that an insulation monitoring device (IMD) indicates the first fault by an audible and/or visual signal which shall continue as long as the fault persists. See further requirements in Annex B. After the occurrence of a first fault, conditions for automatic disconnection of supply in the event of a second fault occurring on a different live conductor shall be as stipulated in normative clause B.1.2.
Figure 2: IT system with earthed high-ohmic mid-point terminal (MP) Figure 3 illustrates an implementation of "IT system with earthed high-ohmic mid-point terminal (MP)" from the power source via the cable system to the ICT equipment. The main Earthing Terminal (MET) is the common earthing point for the high-ohmic mid-point (MP) of the source as well as for the protective earthing conductor (PE).
NOTE 2: The solid lines in Figure 3 associated with the two symmetrical high-ohmic resistors from the mid-point terminal (MP) to L+ and L- respectively are indicating the implementation for functional reasons according to the present document. This arrangement is not part of or a
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Frequently Asked Questions
ETSI EN 301 605 V1.1.1 (2013-10) is a standard published by the European Telecommunications Standards Institute (ETSI). Its full title is "Environmental Engineering (EE); Earthing and bonding of 400 VDC data and telecom (ICT) equipment". This standard covers: DEN/EE-02045
DEN/EE-02045
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