IEC 60695-1-10:2016

IEC 60695-1-10 ®
Edition 2.0 2016-11
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
BASIC SAFETY PUBLICATION
PUBLICATION FONDAMENTALE DE SÉCURITÉ
Fire hazard testing –
Part 1-10: Guidance for assessing the fire hazard of electrotechnical products –
General guidelines
Essais relatifs aux risques du feu –
Partie 1-10: Lignes directrices pour l'évaluation des risques du feu des produits
électrotechniques – Lignes directrices générales

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IEC 60695-1-10 ®
Edition 2.0 2016-11
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
BASIC SAFETY PUBLICATION
PUBLICATION FONDAMENTALE DE SÉCURITÉ

Fire hazard testing –
Part 1-10: Guidance for assessing the fire hazard of electrotechnical products –

General guidelines
Essais relatifs aux risques du feu –

Partie 1-10: Lignes directrices pour l'évaluation des risques du feu des produits

électrotechniques – Lignes directrices générales

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 13.220.40; 29.020 ISBN 978-2-8322-3755-7

– 2 – IEC 60695-1-10:2016  IEC 2016
CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 7
4 Fire hazards associated with electrotechnical products . 9
5 Fundamentals of fire hazard testing . 10
5.1 Objectives . 10
5.2 Fire hazard and fire risk . 10
5.2.1 Fire hazard . 10
5.2.2 Fire risk . 12
5.3 Fire scenarios . 13
5.4 Fire-safety engineering . 15
5.5 Fire hazard assessment . 15
6 Types of fire test . 15
6.1 General . 15
6.2 Quantitative and qualitative groups of fire tests . 15
6.2.1 Quantitative fire tests . 15
6.2.2 Qualitative fire tests . 16
6.3 Types of fire tests . 16
6.3.1 Fire simulation test . 16
6.3.2 Fire resistance tests . 16
6.3.3 Tests with regard to reaction to fire . 16
6.3.4 Preselection fire tests . 16
6.3.5 Basic property tests . 17
7 Appropriate use of qualitative fire tests . 17
8 Preparation of requirements and test specifications . 17
9 Common ignition sources . 18
10 Reference documents of TC 89 . 18
Annex A (informative) The power output of ignition sources . 19
A.1 General . 19
A.2 Some common electrical and non-electrical ignition sources . 19
A.3 Power source classification in IEC 62368-1 [9] . 20
Annex B (informative) Guidance publications and test methods . 21
Bibliography . 23

Table 1 – Common causes of ignition encountered in electrotechnical products . 11
Table 2 – Characteristics of fire stages (from Table 1 in ISO 19706:2011 [22]) . 14
Table A.1 – Examples of ignition sources . 20
Table B.1 – TC 89 guidance publications and test methods . 21

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
FIRE HAZARD TESTING –
Part 1-10: Guidance for assessing the fire hazard of
electrotechnical products – General guidelines

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 60695-1-10 has been prepared by IEC technical committee 89:
Fire hazard testing.
This second edition cancels and replaces the first edition published in 2009. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) reference to IEC 60695-1-12;
b) modified Introduction and Scope;
c) updated normative references;
d) updated terms and definitions;
e) modified Table 1;
– 4 – IEC 60695-1-10:2016  IEC 2016
f) addition of Table 2;
g) new text in Subclauses 5.2, 5.3 and 5.4;
h) mandatory text in Clause 8;
i) Annex B changed to Annex A, and modified;
j) new Annex B concerning common ignition sources.
The text of this standard is based on the following documents:
FDIS Report on voting
89/1341/FDIS 89/1347/RVD
Full information on the voting for the approval of this International Standard can be found in
the report on voting indicated in the above table.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
It has the status of a basic safety publication in accordance with IEC Guide 104 and
ISO/IEC Guide 51.
This standard is to be used in conjunction with IEC 60695-1-11 and IEC 60695-1-12.
A list of all the parts in the IEC 60695 series, under the general title Fire hazard testing, can
be found on the IEC website.
IEC 60695-1 consists of the following parts:
Part 1-10: Guidance for assessing the fire hazard of electrotechnical products – General
guidelines
Part 1-11: Guidance for assessing the fire hazard of electrotechnical products – Fire hazard
assessment
Part 1-12: Guidance for assessing the fire hazard of electrotechnical products – Fire-safety
engineering
Part 1-20: Guidance for assessing the fire hazard of electrotechnical products – Ignitability –
General guidance
Part 1-21: Guidance for assessing the fire hazard of electrotechnical products – Ignitability –
Summary and relevance of test methods
Part 1-30: Guidance for assessing the fire hazard of electrotechnical products – Preselection
testing process – General guidelines
Part 1-40: Guidance for assessing the fire hazard of electrotechnical products – Insulating
liquids
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.
INTRODUCTION
In the design of any electrotechnical product, the risk of fire and the potential hazards
associated with fire need to be considered. In this respect the objective of component, circuit
and equipment design, as well as the choice of materials, is to reduce the risk of fire to a
tolerable level even in the event of reasonably foreseeable (mis)use, malfunction or failure.
This standard, together with its companions, IEC 60695-1-11 and IEC 60695-1-12, provides
guidance on how this is to be accomplished.
The use of compartments with fire-resistant boundaries, and the use of detection and
suppression systems are important methods for the mitigation of fire risk, but are not dealt
with in this standard. Fires involving electrotechnical products can be initiated from external
non-electrical sources. Considerations of this nature are dealt with in an overall fire hazard
assessment.
The aim of the IEC 60695 series of standards is to save lives and property by reducing the
number of fires or reducing the consequences of the fire. This can be accomplished by:
• trying to prevent ignition caused by an electrically energised component part and, in the
event of ignition, to confine any resulting fire within the bounds of the enclosure of the
electrotechnical product;
• trying to minimise flame spread beyond the product’s enclosure and to minimise the
harmful effects of fire effluents including heat, smoke, and toxic or corrosive combustion
products.
Assessing the fire hazard of electrotechnical products is accomplished by performing fire
hazard tests. These tests are divided into two fundamental groups: qualitative fire tests and
quantitative fire tests.
Fire testing of electrotechnical products should, whenever possible, be carried out using
quantitative fire tests having the following characteristics.
a) The test should take into account the circumstances of product use, i.e. contemplated
end-use conditions as well as foreseeable abnormal use. This is because fire conditions
that may be hazardous under one set of circumstances will not necessarily pose the same
threat under a different set.
b) It should be possible to correlate the test results with the harmful effects of fire effluents
referred to above, i.e. the thermal and airborne threats to people and/or property in the
relevant end-use situation. This avoids the creation of artificial, and sometimes distorted,
performance scales with no clear relationship to fire safety.
c) Recognizing that there are usually multiple contributions to the effects of real fires, the
test results should be expressed in well-defined terms and using rational scientific units,
so that the product's contribution to the overall fire effects can be quantitatively assessed
and compared with that of other products’ contributions.
Although quantitative tests are preferred, the characteristics of qualitative fire tests are that
they provide pass/fail and classification results. Under certain circumstances it will be
appropriate to maintain such qualitative test methods or to develop new ones. This part of
IEC 60695-1 establishes the circumstances under which such maintenance or development is
appropriate.
– 6 – IEC 60695-1-10:2016  IEC 2016
FIRE HAZARD TESTING –
Part 1-10: Guidance for assessing the fire hazard of
electrotechnical products – General guidelines

1 Scope
This part of IEC 60695-1 provides general guidance with respect to fire hazard testing on how
to reduce to a tolerable level the risk of fire and the potential effects of fires involving
electrotechnical products. It also serves as a signpost standard to the other guidance
publications in the IEC 60695 series.
It does not give guidance on the use of fire-resistant compartment boundaries or on the use of
detection and suppression systems for the mitigation of fire risk.
It describes the relationship between fire risk and the potential effects of fire, and provides
guidance to IEC product committees on the applicability of qualitative and quantitative fire
tests to the fire hazard assessment of electrotechnical products. Details of the calculation of
fire risk are not included in the scope of this document.
It emphasises the importance of the scenario approach to fire hazard and risk assessment
and discusses criteria intended to ensure the development of technically sound hazard-based
fire test methods.
It discusses the different types of fire tests, in particular the nature of qualitative and
quantitative fire tests. It also describes the circumstances under which it is appropriate for
IEC product committees to maintain or develop qualitative fire tests.
This standard is intended as guidance to IEC committees, and is to be used with respect to
their individual applications.
This basic safety publication is intended for use by technical committees in the preparation of
standards in accordance with the principles laid down in IEC Guide 104 and
ISO/IEC Guide 51.
One of the responsibilities of a technical committee is, wherever applicable, to make use of
basic safety publications in the preparation of its publications. The requirements, test
methods or test conditions of this basic safety publication will not apply unless specifically
referred to or included in the relevant publications.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and
are indispensable for its application. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 60079-0, Explosive atmospheres − Part 0: Equipment − General requirements
IEC 60695-1-11, Fire hazard testing – Part 1-11: Guidance for assessing the fire hazard of
electrotechnical products – Fire hazard assessment

IEC 60695-1-12, Fire hazard testing – Part 1-12: Guidance for assessing the fire hazard of
electrotechnical products – Fire-safety engineering
IEC 60695-1-30, Fire hazard testing – Part 1-30: Guidance for assessing the fire hazard of
electrotechnical products – Preselection testing process – General guidelines
IEC 60695-4:2012, Fire hazard testing – Part 4: Terminology concerning fire tests for
electrotechnical products
IEC Guide 104, The preparation of safety publications and the use of basic safety publications
and group safety publications
ISO/IEC Guide 51, Safety aspects – Guidelines for their inclusion in standards
ISO 13943:2008, Fire safety – Vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60695-4:2012 and
ISO 13943:2008 (some of which are reproduced below), as well as the following, apply.
3.1
fire
〈general〉 process of combustion characterized by the emission of heat and fire effluent and
usually accompanied by smoke, flame, glowing or a combination thereof
Note 1 to entry: In the English language, the term “fire” is used to designate three concepts, two of which, fire
(3.2) and fire (3.3), relate to specific types of self-supporting combustion with different meanings and two of them
are designated using two different terms in both French and German.
[SOURCE: ISO 13943:2008, 4.96]
3.2
fire
〈controlled〉 self-supporting combustion that has been deliberately arranged to provide useful
effects and is limited in its extent in time and space
[SOURCE: ISO 13943:2008, 4.97]
3.3
fire
〈uncontrolled〉 self-supporting combustion that has not been deliberately arranged to provide
useful effects and is not limited in its extent in time and space
[SOURCE: ISO 13943:2008, 4.98]
3.4
fire hazard
physical object or condition with a potential for an undesirable consequence from fire (3.3)
[SOURCE: ISO 13943:2008, 4.112]
___________
Under preparation. Stage at time of publication: IEC/FDIS 60695-1-30:2016.

– 8 – IEC 60695-1-10:2016  IEC 2016
3.5
fire risk
probability of a fire (3.3) combined with a quantified measure of its consequence
Note 1 to entry: It is often calculated as the product of probability and consequence.
[SOURCE: ISO 13943:2008, 4.124]
3.6
fire-safety engineering
application of engineering methods based on scientific principles to the development or
assessment of designs in the built environment through the analysis of specific fire scenarios
(3.7) or through the quantification of risk for a group of fire scenarios
[SOURCE: ISO 13943:2008, 4.126]
3.7
fire scenario
qualitative description of the course of a fire (3.3) with respect to time, identifying key events
that characterise the studied fire and differentiate it from other possible fires
Note 1 to entry: It typically defines the ignition and fire growth processes, the fully developed fire stage, the fire
decay stage, and the environment and systems that impact on the course of the fire.
[SOURCE: ISO 13943:2008, 4.129]
3.8
intermediate-scale fire test
fire test performed on a test specimen of medium dimensions
Note 1 to entry: A fire test performed on a test specimen for which the maximum dimension is between 1 m and
3 m is usually called an intermediate-scale fire test.
[SOURCE: ISO 13943:2008, 4.200]
3.9
large-scale fire test
fire test that cannot be carried out in a typical laboratory chamber, performed on a test
specimen of large dimensions
Note 1 to entry: A fire test performed on a test specimen of which the maximum dimension is greater than 3 m is
usually called a large-scale fire test.
[SOURCE: ISO 13943:2008, 4.205]
3.10
qualitative fire test
fire test which is either:
a) a pass/fail test; or
b) a test which categorizes the behaviour of the test specimen by determining its position in
a rank order of performance
[SOURCE: IEC 60695-4:2012, 3.2.22]
3.11
quantitative fire test
fire test which takes into account the circumstances of product use in which the test
conditions are based on, or are relatable to, the circumstances of use of the test specimen,

and which measures a parameter or parameters, expressed in well-defined terms and using
rational scientific units, which can be used in the quantitative assessment of fire risk
[SOURCE: IEC 60695-4:2012, 3.2.23]
3.12
reaction to fire
response of a test specimen when it is exposed to fire (3.2) under specified conditions in a
fire test
Note 1 to entry: Fire resistance is regarded as a special case and is not normally considered as a reaction to fire
property.
[SOURCE: ISO 13943:2008, 4.272]
3.13
real-scale fire test
fire test that simulates a given application, taking into account the real scale, the real way the
item is installed and used, and the environment
Note 1 to entry: Such a fire test normally assumes that the products are used in accordance with the conditions
laid down by the specifier and/or in accordance with normal practice.
[SOURCE: ISO 13943:2008, 4.273]
3.14
short-circuit
unintended connection of two nodes of an electrical circuit
Note 1 to entry: Current flow can occur, which could cause circuit damage, overheating, fire or explosion.
3.15
small-scale fire test
fire test performed on a test specimen of small dimensions
Note 1 to entry: A fire test performed on a test specimen of which the maximum dimension is less than 1 m is
usually called a small-scale fire test.
[SOURCE: ISO 13943:2008, 4.292]
4 Fire hazards associated with electrotechnical products
The transmission, distribution, storage and utilization of electrical energy can have the
potential to contribute to fire hazard.
With electrotechnical products, the most frequent causes of ignition are overheating and
arcing. The likelihood of ignition will depend on the product and system design, the use of
safety devices and systems, and the type of materials used.
Electrotechnical products, when operating, generate heat. In some cases, arcing and sparking
are normal phenomena. They should not lead to hazardous conditions provided that they have
been taken into account initially at the design stage, and subsequently during installation, use
and maintenance.
Although it is a commonly held belief that most electrical fires are caused by a short-circuit,
there are many other possible causes of ignition. These can include improper installation,
improper usage, and inadequate maintenance. Examples are: operation under overload for
temporary or extended periods; operation under conditions not provided for by the

– 10 – IEC 60695-1-10:2016  IEC 2016
manufacturer or contractor; inadequate heat dissipation; faulty ventilation. Table 1 lists
common ignition phenomena encountered in electrotechnical products.
In Table 1, unless otherwise indicated, the sources of ignition are considered to be internal to
the electrotechnical product. The table lists the most frequently encountered cases.
Fires involving electrotechnical products can also be initiated from external non-electrical
sources. Hazardous conditions, which do not arise from the use of the electrotechnical
product itself, can and often do involve that product. Considerations of this nature are dealt
with in the overall hazard assessment, individual product safety standards, or, for example, by
the provisions of IEC TS 62441 [21].
Examples of the power output of potential ignition sources are provided in Annex A.
When designing products, the prevention of ignition in normal and abnormal operating
conditions requires a higher priority compared to minimizing the eventual spread of flames.
After ignition has occurred, for whatever reason, the effects of the subsequent fire must be
assessed. Factors to be taken into account include:
a) fire growth and flame spread;
b) heat release;
c) smoke generation (visibility);
d) production of toxic fire effluent;
e) production of potentially corrosive fire effluent;
f) the potential for explosion.
References to IEC guidance on items a) to e) can be found in Annex B. The safety of
electrotechnical equipment used in explosive atmospheres is discussed in IEC 60079-0.
5 Fundamentals of fire hazard testing
5.1 Objectives
The objectives of fire hazard testing of electrotechnical products are to determine which fire
properties of the product contribute to the potential effects of fire and/or how the product or
part of the product contributes to the initiation, growth and effect of fire, and then to use this
knowledge to reduce the risks of fire in electrotechnical products.
5.2 Fire hazard and fire risk
5.2.1 Fire hazard
A fire hazard is a physical object or condition with a potential for an undesirable consequence
from fire (see 3.4). Fire hazards therefore encompass potential fuels and ignition sources.
Ignition of an electrotechnical product can be caused by an electrically energised component
part. Ignition occurs as a result of an increase in temperature (see IEC 60695-1-20 [20]) that
may have a chemical, mechanical or electrical origin.
Common ignition phenomena encountered in electrotechnical products are described in detail
in Table 1, which also lists possible consequential effects.
Fires involving electrotechnical products can also be initiated from external non-electrical
sources, and an overall fire hazard assessment should include this possibility.

Table 1 – Common causes of ignition encountered in electrotechnical products
a, b
Cause Possible origins Possible consequential effects and comments
c
Short-circuit (see 3.14) Direct contact of conducting live parts at different Protection devices may not always be activated.
potentials (e.g. because of the loosening of terminals,
The rise in temperature is significant after a very short time and may
disengaged conductors, or ingress of conducting
be localized.
foreign bodies).
Possible emission of light, smoke and/or flammable gases.
Gradual degradation of some components causing
changes in their insulation impedances.
Possible production of flames
Sudden failure of a component or an internal part.
Ignition can occur locally in surrounding components.
Possible release of glowing material.
c
Accidental sparks or arcs A cause external to the product (e.g. overvoltage of the Protection devices may not always be activated.
system network, or an accidental mechanical action
NOTE 1 Some products produce sparks or Possible emission of light, smoke and/or flammable gases.
that exposes live parts).
arcs in normal operation.
Possible production of flames.
An internal cause (e.g. gradual degradation of a
component, or ingress of moisture).
Substantial risk of ignition in potentially explosive atmospheres.
Sudden failure of a component or an internal part.
Ignition can occur locally in surrounding components or gases.
c
High transient peak current A defect in the electrical circuit. Protection devices may not always be activated.
A cause external to the product (e.g. overvoltage of the
system network).
c
An abnormal temperature rise (other than Overcurrent in a conductor. At start-up, protection devices are not normally activated (except in
that caused by any of the above) special protection cases). They may be activated after a variable
Defective contacts.
length of time.
NOTE 2 Some products dissipate heat in
Leakage currents (insulation loss and heating).
normal operation. The temperature rises are gradual and can be very slow. Therefore a
significant accumulation of heat and effluent in the vicinity of the
Failure of a component, an internal part or an
product may result, sufficient to support fire as soon as ignition occurs.
associated system, e.g. ventilation.
Accumulation and diffusion of flammable gases in air may give rise to
Mechanical distortions which modify electrical contacts
an ignition or explosion, especially inside hermetically sealed products.
or the insulation system.
A seized motor shaft (locked rotor) can cause smouldering or flaming
Seizure of a motor shaft (locked rotor).
due to excessive heating of the windings of the motor.
Premature thermal ageing.
a
The sequence indicated is not related to the magnitude or frequency of occurrence.
b
Mechanical distortions and structural changes induced by any one of the four causes can result in the occurrence of one or more of the other three.
c
The protection devices can include thermal (fuse), mechanical (circuit breaker), electrical or electronic types.

– 12 – IEC 60695-1-10:2016  IEC 2016
5.2.2 Fire risk
5.2.2.1 Quantification of fire risk
In order to calculate fire risk, it is necessary to quantify the consequences of the fire that is
being assessed. The consequences may refer to injury or loss of life from threats such as
heat, low oxygen levels, or the concentration of incapacitating fire gases; or the
consequences may refer to loss of property, such as the extent of fire damage. A wide range
of potential fire scenarios may be analysed quantitatively to establish measures of overall fire
risk.
If c is the consequence of the fire (i.e. a quantified measure), and p is the probability of the
fire occurring within a defined time period, then the fire risk (in that time period) is usually
calculated as the product of p and c:
Fire risk = p × c (1)
If it is assumed that, within a given time-frame, that there is a probability, p , of a fire incident
involving a given product in a given scenario (scenario 1), and a probability, p , of a fire
incident involving the same product in a different scenario (scenario 2), and so on, covering
all relevant scenarios, the total fire risk associated with that product, within that time-frame is:
m
Total fire risk = p c (2)
∑ i i
i=1
where
p is the probability of scenario i;
i
c is the consequence of scenario i;
i
m is the total number of scenarios being considered.
NOTE Further discussions of fire risk, and its use in selecting scenarios on which to base fire hazard tests, can
be found in ISO/TS 16732 [1] .
5.2.2.2 Mitigation of fire risk
There are two ways of mitigating fire risks. One is to reduce the probability of occurrence
(reduction of p in Equation 1). The other is to reduce the consequence (reduction of c in
Equation 1). Fire hazard testing is concerned with the reduction of p.
There are several distinct ways in which the probability of fire can be reduced. The most
important, in no particular order, are:
a) product design and selection, including the selection of appropriate materials;
b) containment using fire resistant enclosures and compartment boundaries;
c) the use of appropriate assembly and installation methods;
d) the incorporation of circuit protection devices;
e) the use of detection and suppression systems.
Fire tests (see Clause 6) are used principally for a) and b) and also to some extent for c).
NOTE 1 Guidance on containment and fire resistance testing for buildings is given in the ISO 834 series of
standards [2].
___________
Numbers in square brackets refer to the Bibliography.

NOTE 2 Guidance on detection, activation and suppression is given in ISO/TR 13387-7 [3].
5.3 Fire scenarios
Fire scenarios differ in fire stages (phases), the oxygen content, the CO/CO ratio, the
temperature and the irradiance (see Table 2).
Analysis of the circumstances of use of a product involved in a given fire incident (real or
hypothetical) facilitates the description of the conditions and the chain of events that play a
significant role in the outcome of the fire.
Analysis of product fire incidence using the scenario approach links product fire behaviour to
the outcome of the incident. Part of the rationale for choosing any set of fire hazard tests of
an electrotechnical product should be a description of the fire scenario or scenarios on which
the set of tests is based. This effectively tells the user why this set of test and exposure
conditions was chosen and not another.

– 14 – IEC 60695-1-10:2016  IEC 2016

Table 2 – Characteristics of fire stages (from Table 1 in ISO 19706:2011 [22])
Heat flux to Max. temperature Oxygen volume
[CO]
100× [CO ]
fuel surface Fuel/air 2
%
Fire stage °C equivalence [CO ]

([CO ]+ [CO])
ratio (plume)
% efficiency
kW/m Fuel surface Upper layer Entrained Exhausted
v/v
1. Non-flaming
a. self-sustaining not
d
450 to 800 25 to 85 20 20 – 0,1 to 1 50 to 90
(smouldering) applicable
b. oxidative pyrolysis from
b c c
externally applied – 300 to 600 a 20 20 < 1
radiation
c. anaerobic pyrolysis
b c c
from externally applied – 100 to 500 0 0 >> 1
radiation
d
e
2. Well-ventilated flaming 0 to 60 350 to 650 50 to 500
≈ 20 ≈ 20 < 1 < 0,05 > 95
f
3. Underventilated flaming
a. small, localized fire,
a
generally in a poorly 0 to 30 300 to 600 50 to 500 15 to 20 5 to 10 0,2 to 0,4 70 to 80
> 1
ventilated compartment
g i
h
b. post-flashover fire 50 to 150 350 to 650 0,1 to 0,4 70 to 90
> 600 < 15 < 5 > 1
a
The upper limit is lower than for well-ventilated flaming combustion of a given combustible.
b
The temperature in the upper layer of the fire room is most likely determined by the source of the externally applied radiation and room geometry.
c
There are few data, but for pyrolysis this ratio is expected to vary widely depending on the material chemistry and the local ventilation and thermal conditions.
d
The fire’s oxygen consumption is small compared to that in the room or the inflow, the flame tip is below the hot gas upper layer or the upper layer is not yet significantly
vitiated to increase the CO yield significantly, the flames are not truncated by contact with another object, and the burning rate is controlled by the availability of fuel.
e
The ratio can be up to an order of magnitude higher for materials that are fire-resistant. There is no significant increase in this ratio for equivalence ratios up to ≈ 0,75.
Between ≈ 0,75 and 1, some increase in this ratio can occur.
f
The fire’s oxygen demand is limited by the ventilation opening(s); the flames extend into the upper layer.
g
Assumed to be similar to well-ventilated flaming.
h
The plume equivalence ratio has not been measured; the use of a global equivalence ratio is inappropriate.
i
Instances of lower ratios have been measured. Generally, these result from secondary combustion outside the room vent.

5.4 Fire-safety engineering
Although the definition of fire-safety engineering given in 3.6 is principally concerned with the
major fire safety characteristics of civil engineering scenarios, some aspects of fire-safety
engineering are applicable to electrotechnical products. It follows that, if the principles of fire-
safety engineering are to be adhered to, quantitative fire tests are required. Guidance on fire-
safety engineering is given in IEC 60695-1-12.
5.5 Fire hazard assessment
The methodology of fire hazard assessment is intended to identify significant fire scenarios
associated with a given electrotechnical product in order to establish:
a) the extent to which the fire properties of the product are relevant to the significant
scenarios, and
b) appropriate test methods and performance requirements.
A full fire hazard assessment for a product may involve more than one fire scenario, in which
case the resulting procedure may include several tests and multiple scenario-dependent
performance criteria.
The procedure for conducting a fire hazard assessment of a fire scenario is detailed in
IEC 60695-1-11.
6 Types of fire test
6.1 General
Assessing the fire hazard of electrotechnical products is accomplished by performing fire tests
which, dependent on the maximum dimension of the test specimen, can be small-scale
(see 3.15), intermediate-scale (see 3.8), large-scale (see 3.9) or real-scale tests (see 3.13).
Due to the test criteria, all types of fire hazard tests applied to electrotechnical products are
divided into two fundamental groups: qualitative fire tests (see 3.10) and quantitative fire tests
(see 3.11).
6.2 Quantitative and qualitative groups of fire tests
6.2.1 Quan
...