IEC 60364-4-42:2010/AMD1:2014

IEC 60364-4-42 ®
Edition 3.0 2014-11
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
A MENDMENT 1
AM ENDEMENT 1
Low-voltage electrical installations –
Part 4-42: Protection for safety – Protection against thermal effects

Installations électriques basse tension –
Partie 4-42: Protection pour assurer la sécurité – Protection contre les effets
thermiques
IEC 60364-4-42:2010-05/AMD1:2014-11(en-fr)

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IEC 60364-4-42 ®
Edition 3.0 2014-11
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
A MENDMENT 1
AM ENDEMENT 1
Low-voltage electrical installations –

Part 4-42: Protection for safety – Protection against thermal effects

Installations électriques basse tension –

Partie 4-42: Protection pour assurer la sécurité – Protection contre les effets

thermiques
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX D
ICS 29.120.50; 91.140.50 ISBN 978-2-8322-1919-5

– 2 – IEC 60364-4-42:2010/AMD1:2014
© IEC 2014
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
64/1974/FDIS 64/1982/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• withdrawn,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.
_____________
Add, at the end of 420.2, the following new reference:
IEC 62606, General requirements for arc fault detection devices

Add, after 421.6, the following new clause:
421.7 It is recommended that special measures be taken to protect against the effects of
arc faults in final circuits:
– in premises with sleeping accommodation;
– in locations with risks of fire due to the nature of processed or stored materials, i.e. BE2
locations, (e.g. barns, wood-working shops, stores of combustible materials);
– in locations with combustible constructional materials, i.e. CA2 locations (e.g. wooden
buildings);
– in fire propagating structures, i.e. CB2 locations;
– in locations with endangering of irreplaceable goods.
NOTE 1 A material is considered to be non-combustible if, in compliance with ISO 1182 [31] and ISO 1716 [32], it
does not support combustion.
In a.c. circuits, the use of arc fault detection devices (AFDD) in compliance with IEC 62606
will satisfy the above-mentioned recommendation.

© IEC 2014
If used, an AFDD shall be placed at the origin of the circuit to be protected.
NOTE 2 An AFDD is a device intended to mitigate the effects of arcing faults by initiating disconnection of the
circuit when an arc fault is detected, see Annex B.
The use of AFDDs does not obviate the need to apply one or more measures provided in
other clauses in this standard.
NOTE 3 National committees may decide if the use of AFDDs is made a requirement or a recommendation in their
national standard.
Annex A
(informative)
List of notes concerning certain countries
Add the following:
Country Clause Text
USA 421.7 In the USA, AFDDs are required in the following additional locations:
family rooms, dining rooms, living rooms, parlors, libraries, dens, sunrooms,
recreation rooms, closets, hallways or other rooms in which movement or placement
of furniture or movement by persons has increased the likelihood of damaging
exposed cables
USA 421.7 In the USA, special measures to protect against the effects of arc faults in final
circuits are required in accordance with NFPA 70 article 210.12 [37].

Add the following new Annex B:
Annex B
(informative)
Arc fault detection devices (AFDD)
Fires by electrical installations are often initiated by arc faults that result from parallel arcs, or
series arcs caused by insulation defects between active conductors or loose terminal
connections.
During a series arc fault, there is no leakage current to earth therefore RCDs cannot detect
such a fault. Moreover, the impedance of the series arc fault reduces the load current, in
such case, and the current remains below the tripping threshold of a circuit-breaker or a fuse.
In the case of a parallel arc between line and neutral conductor, the current is limited by the
impedance of the installation and the arc itself, therefore, the resulting fault current could be
lower than the operating current of the overcurrent protective device.
Arc fault detection devices are capable of detecting fault conditions that result from a
sustained arcing junction that could be
...