IEC TR 63054:2017

IEC TR 63054 ®
Edition 1.0 2017-07
TECHNICAL
REPORT
colour
inside
Low-voltage switchgear and controlgear – Fire risk analysis and risk reduction
measures
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IEC TR 63054 ®
Edition 1.0 2017-07
TECHNICAL
REPORT
colour
inside
Low-voltage switchgear and controlgear – Fire risk analysis and risk reduction

measures
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.130.20 ISBN 978-2-8322-4622-1

– 2 – IEC TR 63054:2017 © IEC 2017
CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 7
4 Ignition modes for electrical fires . 8
4.1 General . 8
4.2 Overheating at the connection point due to loose connections . 10
4.2.1 General . 10
4.2.2 Ignition mechanisms . 11
4.2.3 Loose connections mitigation measures . 11
4.3 Overheating of internal power conductors . 14
4.4 Arcs . 14
4.4.1 General . 14
4.4.2 Breaking and making arcs . 15
4.4.3 Arcs occurring at loose connections . 15
4.4.4 Arcing through char and tracking arcs . 16
4.4.5 Sparks . 16
4.4.6 Arcs due to excessive overvoltage . 16
4.5 Failure of electronic components . 16
4.5.1 Basic description of the ignition mechanism . 16
4.5.2 Mitigation measures. 17
5 Conclusion . 17
Bibliography . 19

Figure 1 – Voltage drop and power dissipation versus current values (schematic) [5]. 11
Figure 2 – Current and voltage conditions for switching arcs (schematic) [10] . 15

Table 1 – Ignition phenomena in electrotechnical products . 9
Table 2 – Root causes of electrical fires according to [6] . 10
Table 3 – Potential failure modes for low-voltage switchgear and controlgear . 10
Table 4 – Function of the equipment and glow-wire test temperatures . 13
Table 5 – Relevant source ignition modes for low-voltage switchgear and controlgear . 18

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
LOW-VOLTAGE SWITCHGEAR AND CONTROLGEAR –
FIRE RISK ANALYSIS AND RISK REDUCTION MEASURES

FOREWORD
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The main task of IEC technical committees is to prepare International Standards. However, a
technical committee may propose the publication of a technical report when it has collected
data of a different kind from that which is normally published as an International Standard, for
example "state of the art".
IEC TR 63054, which is a technical report, has been prepared by subcommittee 121A:
Low-voltage switchgear and controlgear, of IEC technical committee 121: Switchgear and
controlgear and their assemblies for low voltage.
The text of this technical report is based on the following documents:
Enquiry draft Report on voting
121A/115/DTR 121A/155/RVDTR
Full information on the voting for the approval of this technical report can be found in the
report on voting indicated in the above table.

– 4 – IEC TR 63054:2017 © IEC 2017
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to
the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
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INTRODUCTION
As fire-ignition hazards are inherent with electricity, installation rules and product standards
for electrical equipment are aimed at providing risk reduction measures and minimizing
residual risk without compromising product safety and function.
Residual risk of low-voltage switchgear and controlgear compliant with IEC 60947 relevant
publications is generally low and, when selected, installed and used according to
manufacturer instruction and installation rules, do not ignite fire in normal operation or
reasonably foreseeable fault conditions.
This document, in accordance to ISO/IEC Guide 51 and IEC Guide 116, describes the fire risk
analysis of electrical equipment and risk reduction measures in IEC 60947 relevant
publications. While intended to apply specifically to low voltage switchgear and controlgear, it
is suggested that other product committees may find this information useful.
The fire hazards, namely the flame ignition mechanisms, relevant for low-voltage switchgear
and controlgear are reviewed and discussed. The related risk reduction measures included in
IEC 60947 relevant publications are subsequently reported for each of those mechanisms.
These measures are based on a system approach, not limited to construction materials
requirements and include design rules and type testing to ensure equipment do not cause
fires in normal operation or due to reasonably foreseeable faulty conditions.

– 6 – IEC TR 63054:2017 © IEC 2017
LOW-VOLTAGE SWITCHGEAR AND CONTROLGEAR –
FIRE RISK ANALYSIS AND RISK REDUCTION MEASURES

1 Scope
This document applies to the fire risk analysis of low-voltage switchgear and controlgear
(hereinafter referred to as "equipment") referring to the IEC 60947 relevant publications,
where the following applies:
– only the case where a fire originates (typically under fault or misuse conditions) within the
equipment;
– only equipment installed in normal environments. Hazardous environments, for example in
presence of combustible materials, is not to be considered;
– only the case of products selected, installed and used according to the manufacturer
instructions and installation rules.
In addition, the following cases are not considered:
– faults addressed by IEC TR 61641;
– risks due to smoke emissions;
– double faults, i.e. multiple phenomenon, potentia
...