DE/EE-02002

Inženiring opreme (EE) – Ozemljitev in povezave telekomunikacijske opreme v telekomunikacijskih centrih

General Information

Status
Published
Publication Date
17-Jan-1995
Technical Committee
Current Stage
12 - Completion
Due Date
12-Jan-1995
Completion Date
18-Jan-1995

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ETS 300 253 E1:2006
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SLOVENSKI STANDARD
SIST ETS 300 253 E1:2006
01-februar-2006
Inženiring opreme (EE) – Ozemljitev in povezave telekomunikacijske opreme v
telekomunikacijskih centrih

Equipment Engineering (EE); Earthing and bonding of telecommunication equipment in

telecommunication centres
Ta slovenski standard je istoveten z: ETS 300 253 Edition 1
ICS:
33.050.01 Telekomunikacijska Telecommunication terminal
terminalska oprema na equipment in general
splošno
SIST ETS 300 253 E1:2006 en

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST ETS 300 253 E1:2006
EUROPEAN ETS 300 253
TELECOMMUNICATION January 1995
STANDARD
Source: ETSI TC-EE Reference: DE/EE-02002
ICS: 33.080
Equipment, earthing, bonding
Key words:
Equipment Engineering (EE);
Earthing and bonding of telecommunication equipment
in telecommunication centres
ETSI
European Telecommunications Standards Institute
ETSI Secretariat
F-06921 Sophia Antipolis CEDEX - FRANCE
Postal address:
650 Route des Lucioles - Sophia Antipolis - Valbonne - FRANCE
Office address:
c=fr, a=atlas, p=etsi, s=secretariat - secretariat@etsi.fr
X.400: Internet:
Tel.: +33 92 94 42 00 - Fax: +33 93 65 47 16

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 1995. All rights reserved.
New presentation - see History box
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ETS 300 253: January 1995

Whilst every care has been taken in the preparation and publication of this document, errors in content,

typographical or otherwise, may occur. If you have comments concerning its accuracy, please write to

"ETSI Editing and Committee Support Dept." at the address shown on the title page.

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Contents

Foreword .......................................................................................................................................................5

Introduction....................................................................................................................................................5

1 Scope ..................................................................................................................................................7

2 Normative references..........................................................................................................................7

3 Abbreviations and definitions ..............................................................................................................8

3.1 Abbreviations .......................................................................................................................8

3.2 Definitions ............................................................................................................................8

3.2.1 IEC definitions (by IEC 50 numbers)...............................................................8

3.2.2 Telecommunication definitions........................................................................9

4 General requirements .......................................................................................................................10

4.1 Safety from electrical hazards............................................................................................10

4.2 Signal reference.................................................................................................................10

4.3 EMC performance..............................................................................................................10

5 Requirements on bonding networks..................................................................................................10

5.1 Bonding configurations ......................................................................................................10

5.2 CBN within a telecommunication building..........................................................................11

5.3 BN within a telecommunication system .............................................................................11

5.4 Merging of CBN and MESH-BNs.......................................................................................14

5.5 Cabling within and between BNs .......................................................................................14

6 Requirements for power distribution .................................................................................................14

6.1 DC power distribution of secondary supply........................................................................14

6.2 DC power distribution of tertiary supplies ..........................................................................14

6.3 AC mains distribution and bonding of the protective conductor.........................................15

6.4 AC power distribution from tertiary power supply ..............................................................15

Annex A (normative): Rationale about CBN co-ordination....................................................................18

Annex B (informative): Rationale about the integration of the DC return conductor into the merged

CBN/MESH-BN ..................................................................................................20

Annex C (informative): Bibliography........................................................................................................21

History..........................................................................................................................................................22

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ETS 300 253: January 1995
Foreword

This European Telecommunication Standard (ETS) has been produced by the Equipment Engineering

(EE) Technical Committee of the European Telecommunications Standards Institute (ETSI).

This ETS has been produced within the framework of the following considerations:

a) centralized telecommunication equipment is generally installed in telecommunication centres and

held in racks, cabinets or other mechanical structures;

b) the existing CCITT 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 telecommunication centres as well as expansion or replacement of

installations in existing telecommunication 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.
Transposition dates
Date of latest announcement of this ETS (doa): 30 April 1995
Date of latest publication of new National Standard 31 October 1995
or endorsement of this ETS (dop/e):
Date of withdrawal of any conflicting National Standard (dow): 31 October 1995
Introduction

This ETS addresses earthing and bonding of telecommunication equipment in telecommunication centres

in relation to safety, functional performance and EMC.

Information regarding the general principles on earthing for telecommunication sites has been published

by the CCITT in the handbook on "Earthing of telecommunication installations" (see annex C). CCITT

Recommendation K.27 deals with bonding configurations and earthing inside a telecommunication

building. One bonding configuration only is selected from CCITT Recommendation K.27 and tailored to

this ETS.
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1 Scope

This European Telecommunication Standard (ETS) applies in telecommunication centres and similar

installations to the bonding network of the building, the bonding network of the equipment, and the

interconnection between these two networks. It contributes to the standardization of telecommunication

equipment and co-ordinates with the pre-requirements of installation conditions to achieve the following

targets:
- safety from electrical hazards;
- reliable signal reference;
- satisfactory Electromagnetic Compatibility (EMC) performance.

A defined bonding configuration down to the equipment level shall facilitate the installation, operation and

maintenance of telecommunication centres in telecommunication buildings or similar installations

independent of the equipment supplier.

The specification of telecommunication equipment and of the pre-requirements of installation are subject

to agreement of the parties (e.g. the supplier and the purchaser). Annex A can be used in the procedure

to achieve agreement.

This ETS does not apply to telecommunication equipment not intended to be installed inside

telecommunication centres, e.g.:
- smaller telecommunication equipment inside a subscriber's building;
- subscriber line terminal equipment.

NOTE: A separate ETS about earthing and bonding of telecommunication equipment inside a

subscriber's building is under consideration.
2 Normative references

This ETS incorporates by dated and undated reference, provisions from other publications. These

normative references are cited at the appropriate places in the text and the publications are listed

hereafter. For dated references, subsequent amendments to or revisions of any of these publications

apply to this ETS only when incorporated in it by amendment or revision. For undated references the latest

edition of the publication referred to applies.

[1] CENELEC HD 384.4.41: "Electrical installation of buildings; Part 4: Protection for

safety; Chapter 41: Protection against electric shock".

[2] CENELEC HD 384.5.54: "Electrical installation of buildings; Part 5: Selection

and erection of electrical equipment; Chapter 54: Earthing arrangements and
protective conductors".
[3] CENELEC EN 60950: "Safety of information technology equipment including
electrical business equipment" (as correspondent to IEC 950).
[4] CENELEC EN 41003: "Particular safety requirements for equipment to be
connected to telecommunication networks".
[5] IEC 50: "International Electrotechnical Vocabulary".
[6] IEC 50 (604): "International Electrotechnical Vocabulary; Chapter
604: Generation, transmission and distribution of electricity - Operation".

[7] IEC 50 (826): "International Electrotechnical Vocabulary; Chapter 826: Electrical

installations of buildings".
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3 Abbreviations and definitions
3.1 Abbreviations
For the purposes of this ETS, the following abbreviations apply:
AC Alternating Current
BN Bonding Network
CBN Common Bonding Network
DC Direct Current
EMC Electromagnetic Compatibility
LPS Lightning Protection System
MESH-BN Meshed Bonding Network
MESH-IBN Meshed Isolated Bonding Network
N Neutral conductor
PE Protective conductor
PEN combined Protective conductor and Neutral conductor
RF Radio Frequency
SRPP System Reference Potential Plane
3.2 Definitions

The following definitions with respect to earthing and bonding are introduced by the IEC 50 [5] and are

used within this ETS to maintain conformity.
3.2.1 IEC definitions (by IEC 50 numbers)
NOTE: IEC 50 [5] references are given in parentheses (see IEC 50 (604) [6] and
IEC 50 (826) [7]).

earth (826-04-01): The conductive mass of earth, whose electric potential at any point is conventionally

taken as equal to zero.

earth electrode (826-04-02): A conductive part or a group of conductive parts in intimate contact with and

providing an electrical connection with earth.

earthing network (604-04-07): The part of an earthing installation that is restricted to the earth electrodes

and their interconnections.

earthing conductor (826-04-07): A protective conductor connecting the main earthing terminal or bar to

the earth electrode.

main earthing terminal (826-04-08): A terminal or bar provided for the connection of protective

conductors, including equipotential bonding conductors and conductors for functional earthing if any, to

the means of earthing.

equipotential bonding (826-04-09): Electrical connection putting various exposed conductive parts and

extraneous conductive parts at a substantially equal potential.

equipotential bonding conductor (826-04-10): A protective conductor for ensuring equipotential

bonding.

Protective conductor (PE) (826-04-05): A conductor required by some measures for protection against

electric shock by electrically connecting any of the following parts:
- exposed conductive parts;
- extraneous conductive parts;
- main earthing terminal;
- earth electrode;
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- earthed point of the source or artificial neutral.

Neutral conductor (N) (826-01-03): A conductor connected to the neutral point of a system and capable

of contributing to the transmission of electrical energy.

PEN conductor (826-04-06): An earthed conductor combining the functions of both protective conductor

and neutral conductor.
IT: See IEC Standard 364-3.
TN-C: See IEC Standard 364-3.
TN-S: See IEC Standard 364-3.
TT: See IEC Standard 364-3.
3.2.2 Telecommunication definitions

The following definitions, specific to telecommunication installations and not covered by the IEC 50 [5], are

used within this ETS. Correspondence to CCITT Recommendation K.27 (see annex C) is indicated as

appropriate.

Bonding Network (BN), (CCITT Recommendation K.27): A 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). 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 this ETS will have an earth connection.

Common Bonding Network (CBN), (CCITT Recommendation K.27): The CBN is the principal means

for effective bonding and earthing inside a telecommunication building. 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.

Meshed Bonding Network (MESH-BN), (CCITT Recommendation K.27): A 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. Consequently, the MESH-BN augments the

CBN (see figure 1).

Meshed Isolated Bonding Network (MESH-IBN), (CCITT Recommendation K.27): A type of IBN in

which the components of the IBN (e.g. equipment frames) are interconnected to form a mesh-like

structure. 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.

system: A regularly interacting or interdependent group of items forming a unified whole.

system block: A 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): A conductive solid plane, as an ideal goal in potential

equalising, is approached in practice by horizontal or vertical meshes. 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.
The SRPP facilitates signalling with reference to a common potential.
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bonding mat: Essential means to provide a SRPP by a discernible, nearly regular mesh structure. The

bonding mat may be located either below or above a collection of equipment constituting a system block.

power supply:

- primary supply: The public mains or, under emergency conditions, a locally generated AC supply;

- secondary supply: The supply to the telecommunication equipment, racks or system block,

derived from the primary supply;

- tertiary supplies: The supplies to the telecommunication equipment, derived from the secondary

supply.

DC return conductor: The (+) conductor of the -48 V or -60 V secondary DC supply.

4 General requirements
4.1 Safety from electrical hazards

To achieve safety it is required to design equipment to the standards EN 60950 [3], EN 41003 [4] and

CENELEC HD 384.4.41 [1] and to perform the installation of PEs and equipotential bonding conductors,

according to CENELEC HD 384.5.54 [2].

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.
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 subclause 4.2. The EMC

requirements addressed include the discharge of electrostatic energy.
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).

CCITT Recommendation K.27 deals with bonding configurations of telecommunication equipment at a

building and installation level. Regarding the bonding configuration at an equipment level a MESH-BN is

explicitly distinguished in this ETS.
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5.2 CBN within a telecommunication building

Each telecommunication building shall be provided with a CBN having sufficiently low impedance and high

current conducting capability to meet the general requirements of clause 4. Equipotential bonding

conductors shall be used (see IEC publication 364-5-54, section 547.1.2).
...

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