IEC 60364-5-55:2011/AMD1:2012

Amendment 1 - Electrical installations of buildings - Part 5-55: Selection and erection of electrical equipment - Other equipment

Amendement 1 - Installations électriques des bâtiments - Partie 5-55: Choix et mise en oeuvre des matériels électriques - Autres matériels

General Information

• Status: Published
• Publication Date: 11-Oct-2012
• ICS: 01 - GENERALITIES. TERMINOLOGY. STANDARDIZATION. DOCUMENTATION
• ICS: 91.140.50 - Electricity supply systems
• Technical Committee: TC 64 - Electrical installations and protection against electric shock
• Drafting Committee: MT 3 - TC 64/MT 3
• Current Stage: PPUB - Publication issued
• Start Date: 15-Oct-2012
• Completion Date: 12-Oct-2012

Relations

• Amends: IEC 60364-5-55:2011 - Electrical installations of buildings - Part 5-55: Selection and erection of electrical equipment - Other equipment
• Effective Date: 05-Sep-2023

Standards Content (Sample)

IEC 60364-5-55 ®
Edition 2.0 2012-10
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
AMENDMENT 1
AMENDEMENT 1
Electrical installations of buildings –
Part 5-55: Selection and erection of electrical equipment – Other equipment

Installations électriques des bâtiments –
Partie 5-55: Choix et mise en oeuvre des matériels électriques – Autres matériels

IEC 60364-5-55:2011/A1:2012
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IEC 60364-5-55 ®
Edition 2.0 2012-10
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
AMENDMENT 1
AMENDEMENT 1
Electrical installations of buildings –

Part 5-55: Selection and erection of electrical equipment – Other equipment

Installations électriques des bâtiments –

Partie 5-55: Choix et mise en oeuvre des matériels électriques – Autres matériels

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX L
ICS 91.140 ISBN 978-2-83220-395-8

– 2 – 60364-5-55 Amend.1 © IEC:2012
FOREWORD
This amendment has been prepared by IEC technical committee 64: Electrical installations
and protection against electric shock.
The text of this amendment is based on the following documents:
FDIS Report on voting
64/1831/FDIS 64/1863/RVD
Full information on the voting for the approval of this amendment can be found in the report
on voting indicated in the above table.
The committee has decided that the contents of this amendment and the base publication will
remain unchanged until the stability date indicated on the IEC web site under
"http://webstore.iec.ch" in the data related to the specific publication. At this date, the
publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
_____________
Insert the following new references into Clause 550.2, Normative references:
IEC 60038, IEC standard voltages
IEC 60364-4-44:2007, Low-voltage electrical installations – Part 4-44: Protection for safety –
Protection against voltage disturbances and electromagnetic disturbances
IEC 60364-5-52:2009, Low-voltage electrical installations – Part 5-52: Selection and erection
of electrical equipment – Wiring systems
IEC 61439-1:2011, Low-voltage switchgear and controlgear assemblies – Part 1: General
rules
IEC 61508 (all parts), Functional safety of electrical/electronic/programmable electronic
safety-related systems
IEC 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 61557-9, 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
Replace "IEC 60364-4-43" by "IEC 60364-4-43:2008.
Insert the following new Clause 557 after Clause 551.8 and before Clause 559:

60364-5-55 Amend.1 © IEC:2012 – 3 –
557 Auxiliary circuits
557.1 Scope
This clause applies to auxiliary circuits, except those covered by specific product or system
standards.
557.2 Terms and definitions
For the purposes of this document, the following definitions apply.
NOTE For general definitions, see IEC 60050-826.
557.2.1
auxiliary circuit
circuit for transmission of signals intended for control, detection, supervision or measurement
of the functional status of a main circuit
557.2.2
main circuit
circuit containing electrical equipment for generation, conversion, distribution or switching of
electrical power or current-using equipment
557.2.3
current-limiting signal output
signal output provided by a device which serves to limit the current
557.2.4
inherently short-circuit and earth fault proof
state of an electric equipment or assembly protected against short-circuits and earth faults by
suitable design and erection provisions
[SOURCE: IEC 60050-826:2004, definition 826-14-15]
557.2.5
safety integrity level
SIL
discrete level for specifying the safety integrity requirements of the safety functions to be
allocated to the electrical/electronic/programmable electronic safety-related systems, where
safety integrity level 4 has the highest level of safety integrity and safety integrity level 1 has
the lowest
[SOURCE: IEC 61508-4:2010, 3.5.8, modified]
557.3 Requirements for auxiliary circuits
557.3.1 General
The power supply a.c. or d.c. for an auxiliary circuit may be either dependent or independent
of the main circuit according to its required function. If the status of the main circuit has to be
signaled, then the signaling circuit shall be able to operate independently of that main circuit.
NOTE In extensive installations the use of a d.c. auxiliary supply may be preferred.
557.3.2 Power supply for auxiliary circuits dependent on the main circuit
557.3.2.1 General
Auxiliary circuits with a power supply dependent on the main a.c. circuit shall be connected to
the main circuit:
– 4 – 60364-5-55 Amend.1 © IEC:2012
– directly (see Figure 557.1); or
– via a rectifier (see Figure 557.2); or
– via transformer (see Figure 557.3).
It is recommended that auxiliary circuits supplying primarily electronic equipment or systems
should not be supplied directly but at least via simple separation from the main circuit.
L1
L2
L3
N
Terminals for the
auxiliary circuit
IEC  1802/12
Figure 557.1 – Auxiliary circuit supplied directly from the main circuit

L1
L2
L3
N
Terminals for the
auxiliary circuit
+ –
IEC  1803/12
Figure 557.2 – Auxiliary circuit supplied via rectifier from the main circuit

L1
L2
L3
N
Terminals for the
auxiliary circuit
IEC  1804/12
Figure 557.3 – Auxiliary circuit supplied from the main circuit via transformer
NOTE In the case of an auxiliary circuit supplied from the main circuit, directly or via the rectifier, the auxiliary
circuit begins at the connection point to the main circuit, see Figure 557.1. When via the rectifier, see Figure 557.2,
or by a transformer supply, see Figure 557.3, the auxiliary circuit begins on the d.c. side of the rectifier or on the
secondary side of the transformer.
557.3.2.2 Auxiliary circuit supplied from the main circuit via transformer
Where an auxiliary circuit is supplied by more than one transformer, they shall be connected
in parallel both on primary and secondary sides.

60364-5-55 Amend.1 © IEC:2012 – 5 –
557.3.3 Auxiliary circuit supplied by an independent source
Where an independent source is used, a loss of supply or undervoltage of the main circuit
source should be detected. An independent auxiliary circuit shall not create a hazardous
situation.
NOTE Batteries and a power supply system independent of the mains are examples of independent sources.
557.3.4 Auxiliary circuits with or without connection to earth
General
557.3.4.1
An auxiliary circuit shall comply with the earthing requirements in IEC 60364, except as
modified by 557.3.4.2 or 557.3.4.3.
NOTE It depends on the requirements for an auxiliary circuit as to whether it is operated earthed or unearthed.
For example, in earthed auxiliary circuits an earth fault in a non-earthed conductor leads to a switching off of the
power supply of the auxiliary circuit. In unearthed auxiliary circuits, an earth fault in a conductor leads only to a
signal from the IMD (see 557.3.4.3).
The use of unearthed auxiliary circuits should be considered, where high reliability is required.
557.3.4.2 Earthed auxiliary circuit
Earthed auxiliary circuits supplied via a transformer shall be connected to earth only at one
point on the secondary side of the transformer. The connection to earth shall be situated
close to the transformer. The connection shall be easily accessible and capable of being
isolated for insulation measurement.
557.3.4.3 Unearthed auxiliary circuit
If an auxiliary circuit is operated unearthed via a transformer, an insulation monitoring device
(IMD) according to IEC 61557-8 shall be installed on the secondary side.
NOTE Depending on a risk assessment it should be determined if the signal of the IMD is to initiate an acoustic
and/or flash alarm or transmit it to a monitoring system.
557.3.5 Power supplies for auxiliary circuits
557.3.5.1 General
The rated voltage of the auxiliary circuit and the components used in the circuit shall be
compatible with the supply to that circuit.
NOTE If the supply voltage is too low for the design of the circuit, then the operation will not be reliable, e.g. for
the proper function of relays.
Consideration should be given to the effects of voltage drop on the correct function of the
electrical equipment of the auxiliary circuit, e.g.:
– for an a.c. supply, relays and solenoid valves may have an inrush current of 7 to 8 times of
the holding current;
– for a d.c. supply, the inrush current is equal to the steady current;
– in the case of motors starting direct-on-line, the starting current could reduce the supply
voltage of an auxiliary circuit dependent on the main circuit below the minimum operating
voltage of the associated switchgear.
557.3.5.2 Standby power supply or power supply for safety services
Where a standby power supply or a power supply from a generating set is used to supply
auxiliary circuits, the frequency variation shall be taken into account.

– 6 – 60364-5-55 Amend.1 © IEC:2012
557.3.5.3 AC supply
The nominal voltage of control circuits should preferably not exceed
– 230 V for circuits with 50 Hz nominal frequency,
– 277 V for circuits with 60 Hz nominal frequency,
respectively, taking into account voltage tolerances according to IEC 60038.
The dimensioning of cable length with respect to the conductor capacitances, e.g. connection
to a limit switch, needs to be c
...