IEC TS 60695-8-3:2008

IEC/TS 60695-8-3
Edition 1.0 2008-04
TECHNICAL
SPECIFICATION
SPÉCIFICATION
TECHNIQUE
Fire hazard testing –
Part 8-3: Heat release – Heat release of insulating liquids used in
electrotechnical products
Essais relatifs aux risques du feu –
Partie 8-3: Dégagement de chaleur – Dégagement de chaleur des liquides
isolants utilisés dans les produits électrotechniques

IEC/TS 60695-8-3:2008
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IEC/TS 60695-8-3
Edition 1.0 2008-04
TECHNICAL
SPECIFICATION
SPÉCIFICATION
TECHNIQUE
Fire hazard testing –
Part 8-3: Heat release – Heat release of insulating liquids used in
electrotechnical products
Essais relatifs aux risques du feu –
Partie 8-3: Dégagement de chaleur – Dégagement de chaleur des liquides
isolants utilisés dans les produits électrotechniques

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
N
CODE PRIX
ICS 13.220.40; 29.020 ISBN 2-8318-9723-8

– 2 – TS 60695-8-3 © IEC:2008
CONTENTS
FOREWORD.3
INTRODUCTION.5

1 Scope.6
2 Normative references .6
3 Terms and definitions .6
4 General description of the test.9
5 Test apparatus .9
5.1 Cone calorimeter .9
5.2 Test specimen tray .9
5.3 Position of the test specimen tray.10
6 Calibration.10
7 Preparation of the test specimen .10
8 Test method .11
8.1 Critical ignition flux determination.11
8.1.1 Introduction .11
8.1.2 Procedure.11
8.2 Test procedure .11
9 Calculation .11
10 Test report.11
11 Precision data .12

Annex A (informative) Precision data .13

Bibliography.14

Figure 1 – Example of test specimen tray .10

TS 60695-8-3 © IEC:2008 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
FIRE HAZARD TESTING –
Part 8-3: Heat release –
Heat release of insulating liquids used
in electrotechnical products
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
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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 provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with an IEC Publication.
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.
The main task of IEC technical committees is to prepare International Standards. In
exceptional circumstances, a technical committee may propose the publication of a technical
specification when
• the required support cannot be obtained for the publication of an International Standard,
despite repeated efforts, or
• the subject is still under technical development or where, for any other reason, there is the
future but no immediate possibility of an agreement on an International Standard.
Technical specifications are subject to review within three years of publication to decide
whether they can be transformed into International Standards.
IEC 60695-8-3, which is a technical specification, has been prepared by IEC technical
committee 89: Fire hazard testing.
It has the status of a basic safety publication in accordance with IEC Guide 104.

– 4 – TS 60695-8-3 © IEC:2008
The text of this technical specification is based on the following documents:
Enquiry draft Report on voting
89/801/DTS 89/816/RVC
Full information on the voting for the approval of this technical specification can be found in
the report on voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
This technical specification is to be used in conjunction with ISO 5660-1, ISO 5660-2 and
IEC 60695-8-1.
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 60695-8, under the general heading Fire hazard testing – Part 8: Heat release, consists
of the following parts:
Part 8-1: General guidance
Part 8-2: Summary and relevance of test methods
Part 8-3: Heat release of insulating liquids used in electrotechnical products
The committee has decided that the contents of this publication will remain unchanged until
the maintenance result 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
• transformed into an International standard;
• reconfirmed;
• withdrawn;
• replaced by a revised edition; or
• amended.
TS 60695-8-3 © IEC:2008 – 5 –
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 to acceptable levels the
potential risks of fire even in the event of foreseeable abnormal use, malfunction or failure.

The future IEC 60695-1-10 [1] , together with its companion, the future IEC 60695-1-1 [2],
provide guidance on how this is to be accomplished.
The primary aims are to prevent ignition caused by an electrically energized component part
and, in the event of ignition, to confine any resulting fire within the bounds of the enclosure of
the electrotechnical product. Secondary aims include the minimization of any flame spread
beyond the product’s enclosure and the minimization of harmful effects of fire effluents
including heat, smoke and toxic or corrosive combustion products.
Fires involving electrotechnical products can also be initiated from external non-electrical
sources. Considerations of this nature are dealt with in the overall risk assessment.
Fires are responsible for creating hazards to life and property as a result of the generation of
heat (thermal hazard), the production of toxic and/or corrosive compounds, and the
obscuration of vision due to smoke. Fire risk increases as the heat released increases,
possibly leading to a flash-over fire.
One of the most important measurements in fire testing is the measurement of heat release,
and it is used as an important factor in the determination of fire hazard; it is also used as one
of the parameters in fire safety engineering calculations.
The measurement and use of heat release data, together with other fire test data, can be
used to reduce the likelihood of (or the effects of) fire, even in the event of foreseeable
abnormal use, malfunction or failure of electrotechnical products.
When a material is heated by some external source, fire effluent can be generated and can
form a mixture with air which can ignite and initiate a fire. Some of the heat released in the
process is carried away by the fire effluent-air mixture, some is radiatively lost, and some is
transferred back to the material, to generate further pyrolysis products, thus continuing the
process.
Heat may also be transferred to other nearby products, which may burn and then release
additional heat and fire effluent.
The rate at which thermal energy is released in a fire is defined as the heat release rate. Heat
release rate is important because of its influence on flame spread and on the initiation of
secondary fires. Other characteristics are also important, such as ignitability, flame spread
and the side-effects of the fire (see the IEC 60695 series).
This technical specification, is based on the use of the cone calorimeter which is an
instrument which measures heat release rate as well as other useful fire hazard parameters
such as smoke production, ignition time and mass loss.
The need for heat release data from the combustion of insulating liquids is mentioned in
IEC 60695-1-40 [3]. This technical specification provides a method for measuring the heat
release from such materials and is also applicable to other combustible liquids. Guidance on
the use of the cone calorimeter is given in ISO 5660-3 [4] and in IEC 60695-8-2 [5].
___________
Figures in square brackets refer to the bibliography.

– 6 – TS 60695-8-3 © IEC:2008
FIRE HAZARD TESTING –
Part 8-3: Heat release –
Heat release of insulating liquids used
in electrotechnical products
1 Scope
IEC 60695-8-3, which is a technical specification, specifies quantitative test methods for
determining the heat release from the combustion of insulating liquids of electrotechnical
products when exposed to a defined heat flux with spark ignition. Smoke production, ignition
times and mass loss are also measured. This technical specification may also be applicable to
other liquid test specimens.
This technical specification is intended for use by technical committees in the preparation of
standards in accordance with the principles laid down in IEC Guide 104 and in
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.
HAZARD WARNING
The testing of volatile liquids with this apparatus can lead to explosions so it is
essential to examine all liquids using the preliminary testing procedure described in 8.1.
2 Normative references
The following referenced documents are indispensable for the application of this document.
For dated references, only the edition cited applies. For undated references, the latest edition
of the referenced document (including any amendments) applies.
IEC 60695-8-1, Fire hazard testing – Part 8-1: Heat release – General guidance
ISO 5660-1:2002, Reaction-to-fire tests – Heat release, smoke production and mass loss rate
– Part 1: Heat release rate (cone calorimeter method)
ISO 5660-2:2002, Reaction-to-fire tests – Heat release, smoke production and mass loss rate
– Part 2: Smoke production rate (dynamic measurement)
ISO/IEC Guide 51:1999, Safety aspects – Guidelines for their inclusion in standards
IEC Guide 104:1997, The preparation of safety publications and the use of basic safety
publications and group safety publications
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.

TS 60695-8-3 © IEC:2008 – 7 –
3.1
combustion
exothermic reaction of a substance with an oxidizer
NOTE Combustion generally emits fire effluent accompanied by flames and/or visible light.
[ISO/IEC 13943, definition 23] [7]
3.2
critical ignition flux
-2
minimum heat flux, which is a multiple of 5 kW⋅m and which with spark ignition causes a test
specimen to ignite in less than 1 200 s
3.3
extinction coefficient of smoke
natural logarithm of the opacity of smoke divided by the path length of the light used to
measure the smoke opacity
[IEC 60695-4, definition 3.18] [6]
3.4
fire
〈general〉 process of combustion characterized by the emission of heat and fire effluent
accompanied by smoke, and/or flame, and/or glowing
3.5
fire
〈controlled〉 self-supporting combustion which has been deliberately arranged to provide
useful effects and which is controlled in its extent in time and space
NOTE In the English language the word "fire" can have two meanings which translate into two different words in
both French and German.
[ISO/IEC 13943, definition 40] [7]
3.6
fire
〈uncontrolled〉 self-supporting combustion which spreads uncontrolled in time and space
[ISO/IEC 13943, definition 41] [7]
3.7
fire effluent
totality of gases and/or aerosols (including suspended particles) created by combustion or
pyrolysis
[ISO/IEC 13943, definition 45] [7]
3.8
fire hazard
physical object or condition with a potential for an undesirable consequence from fire
3.9
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
or through the quantification of risk for a group of fire scenarios

– 8 – TS 60695-8-3 © IEC:2008
3.10
flame spread
propagation of a flame front
[IEC 60695-4, definition 3.36] [6]
3.11
heat flux
amount of thermal energy emitted, transmitted or received per unit area and unit time
NOTE It is expressed in watts per square metre.
3.12
heat release
thermal energy produced by combustion
NOTE The typical units are joules.
3.13
heat release rate
rate of thermal energy production generated by combustion
NOTE The typical units are watts.
3.14
ignition
initiation of combustion
NOTE The term “ignition” in French has a very different meaning (state of body combustion).
[ISO/IEC 13943, definition 96] [7]
3.15
mass loss rate
mass of material lost per unit time under specified conditions
NOTE It is expressed in kilograms per second.
[ISO/IEC 13943, definition 119] [7]
3.16
opacity (of smoke)
the ratio (I/T) of incident luminous flux (I) to transmitted luminous flux (T) through smoke,
under specified test conditions
[IEC 60695-4, definition 3.67] [6]
3.17
oxygen consumption principle
proportional relationship between the mass of oxygen consumed during combustion and the
heat released
-1
NOTE A value of 13,1 kJ⋅g is commonly used.
3.18
pyrolysis
chemical decomposition of a substance by the action of heat
NOTE 1 The term is often used to refer to a stage of fire before flaming combustion has occurred.
NOTE 2 In fire science no assumption is made about the presence or absence of oxygen.

TS 60695-8-3 © IEC:2008 – 9 –
3.19
quantitative fire test
fire test which takes into account the circumstances of product use on which the test
conditions are based or to which they can be related, and which measures a parameter or
parameters, expressed in well defined terms and using rational scientific units, can be used in
the quantitative assessment of fire risk
NOTE Such a test is sometimes referred to as a “performance-based fire test”.
3.20
smoke
a visible suspension of solid and/or liquid particles in gases resulting from combustion or
pyrolysis
[IEC 60695-4, definition 3.79] [6]
3.21
smoke production
amount of smoke which is produced in a fire or fire test
3.22
smoke production rate
amount of smoke produced per unit time in a fire or fire test
NOTE 1 It is calculated as the product of the volumetric flow rate of smoke and the extinction coefficient of the
smoke at the point of measurement.
2 –1
NOTE 2 The typical units are m ⋅s .
4 General description of the test
The test is performed to determine the heat release rate, total heat release, smoke production
rate, total smoke production, time to ignition and mass loss rate of insulating liquids used in
electrotechnical products when exposed to specified heating conditions. For the purpose of
the test, the test apparatus specified in ISO 5660-1 and ISO 5660-2 and additional equipment
given in this standard shall be used.
The liquid test specimen, contained in a test specimen tray, is heated by a heat flux radiated
from a conical electric heater set above the test specimen tray, and an electrical spark is
applied as an ignition source.
The heat release rate is measured using the oxygen consumption technique. The smoke
production rate is measured by a laser beam system installed in the exhaust duct of the test
apparatus. A load cell records mass measurements.
5 Test apparatus
5.1 Cone calorimeter
The test apparatus specified in ISO 5660-1 and ISO 5660-2 shall be used with the exception
of the test specimen tray which is replaced by the test specimen tray described in 5.2.
5.2 Test specimen tray
The test specimen tray shall have the shape of a square pan with an opening of 100 mm ±
1 mm × 100 mm ± 1 mm at the top and an inside depth of 15 mm ± 1 mm. It shall be made of
stainless steel plate with a thickness of 2,15 mm ± 0,25 mm. It shall include a handle to
facilitate insertion and removal, and shall include a mechanism to ensure the central location

– 10 – TS 60695-8-3 © IEC:2008
of the test specimen under the heater and proper alignment with the load cell. An example of
the test specimen tray is shown in Figure 1.
22 60 22 22 60 8 14
IEC  548/08
Dimensions in millimetres
Figure 1 – Example of test specimen tray
5.3 Position of the test specimen tray
The test specimen tray shall be located so that the surface of the liquid test specimen is
25 mm ± 1 mm below the lower edge of the conical heater.
6 Calibration
The calibration shall be conducted in accordance with ISO 5660-1 and ISO 5660-2.
The heat flux level shall be determined at a position in the centre of the surface of the liquid
test specimen. The heat flux level at a position corresponding to the centre of the rear surface
of the liquid test specimen shall also be determined.
7 Preparation of the test specimen
3 3
For the preliminary test, 20 cm ± 1 cm of liquid shall be used to determine the critical
3 3
ignition flux. For the main testing, 50 cm ± 1 cm of liquid shall be used.
NOTE It is probable that some of the liquids likely to be tested using this method will be highly viscous. Transfer
of liquid to the test specimen holder is best done using a syringe or by weighing 50 cm of the liquid and then
transferring that mass into the test specimen tray on a balance.
8 40
22 60 22
TS 60695-8-3 © IEC:2008 – 11 –
8 Test method
The test shall be conducted in accordance with the test procedure specified in ISO 5660-1.
Smoke production shall be measured in accordance with ISO 5660-2, except that the heat flux
conditions shall be as described in 8.1 and 8.2.
8.1 Critical ignition flux determination
8.1.1 Introduction
Before testing can be undertaken, it is essential to confirm that the liquid can be safely tested.
–2
This is done by finding the critical ignition flux of the liquid to the nearest 5 kW⋅m . Testing is
–2
started at 0 kW⋅m and subsequent tests are carried out at increasing heat fluxes, at
–2 –2
increments of 5 kW⋅m ± 0,2 kW⋅m , until the test specimen ignites in less than 1 200 s.
8.1.2 Procedure
The following steps should be performed:
3 3
a) place 20 cm ± 1 cm of the liquid in the test specimen holder;
b) place the test specimen screen in position;
c) place the test specimen holder under the cone heater set at zero irradiance;
d) remove the screen and simultaneously activate the spark igniter. If the test specimen
ignites within 1 200 s, record the time to ignition and start testing in accordance with 8.2 or,
e) if the test specimen has not ignited within 1 200 s, repeat the procedure at increasing
–2 –2
levels of irradiance, in steps of 5 kW⋅m ± 0,2 kW⋅m until ignition occurs within 1 200 s.
Record the time to ignition and start testing in accordance with 8.2.
8.2 Test procedure
The test procedure is as follows:
a) calibrate the cone calorimeter in accordance with the procedure outlined in ISO 5660-1
and set the heat flux to the critical ignition flux as found in 8.1;
3 3
b) transfer 50 cm ± 1 cm of the test liquid into the test specimen holder;
c) place the test specimen screen in position;
d) place the test specimen holder under the cone heater;
e) remove the screen and simultaneously activate the spark igniter. Collect all data as
required by ISO 5660-1.
9 Calculation
The calculation of test results shall be carried out in accordance with ISO 5660-1 and
ISO 5660-2.
NOTE If the test specimen contains significant amounts of an element or elements other than hydrogen, carbon
and oxygen, it should be noted that the heat release per unit mass consumption of oxygen may differ from the
-1
13,1 kJ⋅g value which is used for the oxygen consumption calorimetry calculations.
10 Test report
Items listed in the test report (Clause 13 of both ISO 5660-1 and ISO 5660-2) shall be
detailed.
– 12 – TS 60695-8-3 © IEC:2008
11 Precision data
Precision data are given in Annex A.

TS 60695-8-3 © IEC:2008 – 13 –
Annex A
(informative)
Precision data
NOTE Interlaboratory trials are underway to obtain precision data.

– 14 – TS 60695-8-3 © IEC:2008
Bibliography
[1] IEC 60695-1-10, Fire hazard testing – Part 1-10: Guidance for assessing the fire hazard of
electrotechnical products – General guidelines
[2] IEC 60695-1-11, Fire hazard
...