IEC TR 60695-8-2:2008

IEC/TR 60695-8-2
Edition 2.0 2008-01
TECHNICAL
REPORT
RAPPORT
TECHNIQUE
Fire hazard testing –
Part 8-2: Heat release – Summary and relevance of test methods

Essais relatifs aux risques du feu –
Partie 8-2: Dégagement de chaleur – Résumé et pertinence des méthodes
d'essais
IEC/TR 60695-8-2:2008
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by
any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either IEC or
IEC's member National Committee in the country of the requester.
If you have any questions about IEC copyright or have an enquiry about obtaining additional rights to this publication,
please contact the address below or your local IEC member National Committee for further information.

Droits de reproduction réservés. Sauf indication contraire, aucune partie de cette publication ne peut être reproduite
ni utilisée sous quelque forme que ce soit et par aucun procédé, électronique ou mécanique, y compris la photocopie
et les microfilms, sans l'accord écrit de la CEI ou du Comité national de la CEI du pays du demandeur.
Si vous avez des questions sur le copyright de la CEI ou si vous désirez obtenir des droits supplémentaires sur cette
publication, utilisez les coordonnées ci-après ou contactez le Comité national de la CEI de votre pays de résidence.

IEC Central Office
3, rue de Varembé
CH-1211 Geneva 20
Switzerland
Email: inmail@iec.ch
Web: www.iec.ch
About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.

About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigenda or an amendment might have been published.
ƒ Catalogue of IEC publications: www.iec.ch/searchpub
The IEC on-line Catalogue enables you to search by a variety of criteria (reference number, text, technical committee,…).
It also gives information on projects, withdrawn and replaced publications.
ƒ IEC Just Published: www.iec.ch/online_news/justpub
Stay up to date on all new IEC publications. Just Published details twice a month all new publications released. Available
on-line and also by email.
ƒ Electropedia: www.electropedia.org
The world's leading online dictionary of electronic and electrical terms containing more than 20 000 terms and definitions
in English and French, with equivalent terms in additional languages. Also known as the International Electrotechnical
Vocabulary online.
ƒ Customer Service Centre: www.iec.ch/webstore/custserv
If you wish to give us your feedback on this publication or need further assistance, please visit the Customer Service
Centre FAQ or contact us:
Email: csc@iec.ch
Tel.: +41 22 919 02 11
Fax: +41 22 919 03 00
A propos de la CEI
La Commission Electrotechnique Internationale (CEI) est la première organisation mondiale qui élabore et publie des
normes internationales pour tout ce qui a trait à l'électricité, à l'électronique et aux technologies apparentées.

A propos des publications CEI
Le contenu technique des publications de la CEI est constamment revu. Veuillez vous assurer que vous possédez
l’édition la plus récente, un corrigendum ou amendement peut avoir été publié.
ƒ Catalogue des publications de la CEI: www.iec.ch/searchpub/cur_fut-f.htm
Le Catalogue en-ligne de la CEI vous permet d’effectuer des recherches en utilisant différents critères (numéro de référence,
texte, comité d’études,…). Il donne aussi des informations sur les projets et les publications retirées ou remplacées.
ƒ Just Published CEI: www.iec.ch/online_news/justpub
Restez informé sur les nouvelles publications de la CEI. Just Published détaille deux fois par mois les nouvelles
publications parues. Disponible en-ligne et aussi par email.
ƒ Electropedia: www.electropedia.org
Le premier dictionnaire en ligne au monde de termes électroniques et électriques. Il contient plus de 20 000 termes et
définitions en anglais et en français, ainsi que les termes équivalents dans les langues additionnelles. Egalement appelé
Vocabulaire Electrotechnique International en ligne.
ƒ Service Clients: www.iec.ch/webstore/custserv/custserv_entry-f.htm
Si vous désirez nous donner des commentaires sur cette publication ou si vous avez des questions, visitez le FAQ du
Service clients ou contactez-nous:
Email: csc@iec.ch
Tél.: +41 22 919 02 11
Fax: +41 22 919 03 00
IEC/TR 60695-8-2
Edition 2.0 2008-01
TECHNICAL
REPORT
RAPPORT
TECHNIQUE
Fire hazard testing –
Part 8-2: Heat release – Summary and relevance of test methods

Essais relatifs aux risques du feu –
Partie 8-2: Dégagement de chaleur – Résumé et pertinence des méthodes
d'essais
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
S
CODE PRIX
ICS 13.220.40; 29.020 ISBN 2-8318-9578-2

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

1 Scope.6
2 Normative references.6
3 Terms and definitions .7
4 Summary of test methods .9
4.1 Measurement of complete combustion .10
4.1.1 The bomb calorimeter .10
4.2 Measurements of incomplete combustion.11
4.2.1 Cone calorimeter .11
4.2.2 The Ohio State University calorimeter .12
4.2.3 Vertical cable ladder tests .13
4.2.4 SBI test .15
4.2.5 Horizontal cable ladder test.17
4.2.6 Open calorimetry fire tests .19

Bibliography .20

Table 1 – Summary and comparison of vertical cable ladder tests.16

TR 60695-8-2 © IEC:2008 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
FIRE HAZARD TESTING –
Part 8-2: Heat release –
Summary and relevance of test methods

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 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. 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 60695-8-2, which is a technical report, has been prepared by IEC technical committee 89:
Fire hazard testing.
This second edition cancels and replaces the first edition of IEC 60695-8-2/TS published in
2000 and constitutes a technical revision.
The main changes with respect to the previous edition are listed below:
– editorial changes throughout;

– 4 – TR 60695-8-2 © IEC:2008
– revised terms and definitions;
– introduction of a new Subclause 4.1.1 – Bomb calorimeter;
– introduction of a new Table 1 dealing with vertical ladder tests;
– introduction of a new Subclause 4.2.4 – SBI test method;
– introduction of a new Subclause 4.2.6 – Open calorimetry fire tests.
It has the status of a basic safety publication in accordance with IEC Guide 104 and ISO/IEC
Guide 51.
This technical report is to be used in conjunction with IEC 60695-8-1.
The text of this technical report is based on the following documents:
Enquiry draft Report on voting
89/808/DTR 89/830A/RVC
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.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
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.
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
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
TR 60695-8-2 © 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.
)
IEC 60695-1-10 [1] , together with its companion, IEC 60695-1-11 [2] , provide guidance on
how this is to be accomplished.
The primary aims are as follows:
1) to prevent ignition caused by an electrically energized component part, and
2) 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 heat
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), toxic and/or corrosive compounds and 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. The heat released in the process is
carried away by the fire effluent-air mixture, radiatively lost or transferred back to the solid
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
other side effects of the fire (see the IEC 60695 series of standards).
___________
)
Figures in square brackets refer to the bibliography.

– 6 – TR 60695-8-2 © IEC:2008
FIRE HAZARD TESTING –
Part 8-2: Heat release –
Summary and relevance of test methods

1 Scope
This part of IEC 60695 presents a summary of published test methods that are relevant to
determine heat release for electrotechnical products. It represents the current state of the art
of the test methods and, where available, includes special observations on their relevance and
use. The list of test methods is not to be considered exhaustive, and test methods which were
not developed by IEC/TC 89 are not to be considered as endorsed by IEC TC89 unless this is
specifically stated.
Heat release data can be used as part of fire hazard assessment and in fire safety engineering,

as discussed in IEC 60695-1-10 [1] and IEC 60695-1-11 [2].
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 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 60695-4:2005, Fire hazard testing – Part 4: Terminology concerning fire tests for
electrotechnical products
IEC 60695-8-1:2001, Fire hazard testing – Part 8-1: Heat release – General guidance
IEC Guide 104:1997, The preparation of safety publications and the use of basic safety
publications and group safety publications
ISO/IEC Guide 51:1999, Safety aspects – Guidelines for their inclusion in standards
ISO/IEC 13943:2000, Fire safety – Vocabulary

TR 60695-8-2 © IEC:2008 – 7 –
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply. Other terms and
definitions are as given in IEC 60695-4 and ISO 13943.
3.1
combustion
exothermic reaction of a substance with an oxidizing agent
NOTE Combustion generally emits fire effluent accompanied by flames and/or glowing.
[ISO/IEC 13943, definition 23 modified]
3.2
combustion products
solid, liquid and gaseous material resulting from combustion
NOTE Combustion products may include fire effluent, ash, char, clinker and/or soot.
3.3
complete combustion
combustion in which all the combustion products are fully oxidized
NOTE 1 This means that when the oxidizing agent is oxygen, all carbon is converted to carbon dioxide and all
hydrogen is converted to water.
NOTE 2 If elements other than carbon, hydrogen and oxygen are involved in the combustion process, then it may
not be possible to uniquely define complete combustion.
3.4
controlled fire
fire which has been deliberately arranged to provide useful effects and which is controlled in its
extent in time and space
3.5
effective heat of combustion
heat released from a burning test specimen in a given time interval divided by the mass lost
from the test specimen in the same time period
NOTE 1 It is the same as the net heat of combustion if all the test specimen is converted to volatile combustion
products and if all the combustion products are fully oxidized.
-1
NOTE 2 The typical units are kJ⋅g .
3.6
fire
process of combustion characterized by the emission of heat and fire effluent accompanied by
smoke, and/or flame, and/or glowing
3.7
fire effluent
totality of gases and/or aerosols (including suspended particles) created by combustion or
pyrolysis
[ISO/IEC 13943, definition 45]
3.8
fire hazard
physical object or condition with a potential for an undesirable consequence from fire

– 8 – TR 60695-8-2 © IEC:2008
3.9
fire safety engineering
application of engineering methods based on scientific principles for 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
3.10
fire test
procedure designed to measure or assess either fire behaviour or the response of a test
specimen to one or more aspects of fire
3.11
flash-over
transition to a state of total surface involvement in a fire of combustible materials within an
enclosure
[ISO/IEC 13943, definition 77]
3.12
gross heat of combustion
heat of combustion of a substance when the combustion is complete and any produced water
is entirely condensed under specified conditions
[ISO/IEC 13943, definition 86.2]
3.13
heat of combustion
thermal energy produced by combustion of unit mass of a given substance
-1
NOTE The typical units are kJ⋅g .
See also 3.5, 3.12 and 3.18.
3.14
heat release
thermal energy which is produced in a fire or fire test
NOTE The typical units are joules.
3.15
heat release rate
thermal energy released per unit time in a fire or fire test
NOTE The typical units are watts.
3.16
intermediate-scale fire test
fire test performed on a test specimen of medium dimensions
NOTE This definition usually applies to a fire test performed on a test specimen of which the maximum dimension
is between 1 m and 3 m.
3.17
large-scale fire test
fire test, which cannot be carried out in a typical laboratory chamber, performed on a test
specimen of large dimensions
NOTE This definition usually applies to a fire test performed on a test specimen of which the maximum dimension
is greater than 3 m.
TR 60695-8-2 © IEC:2008 – 9 –
3.18
net heat of combustion
heat of combustion when any water produced is considered to be in the gaseous state
NOTE The net heat of combustion is always smaller than the gross heat of combustion because the heat released
by the condensation of the water vapour is not included.
3.19
oxidation
chemical reaction in which the proportion of oxygen or other electronegative element in a
substance is increased
NOTE In chemistry, the term has the broader meaning of a process which involves the loss of an electron or
electrons from an atom, molecule or ion.
3.20
oxidizing agent
substance capable of causing oxidation
NOTE Combustion is an oxidation.
3.21
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.
3.22
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.
3.23
small-scale fire test
fire test performed on a test specimen of small dimensions
NOTE This definition usually applies to a fire test performed on a test specimen of which the maximum dimension
is less than 1 m.
3.24
test specimen
item subjected to a procedure of assessment or measurement
NOTE In a fire test, the item may be a material, product, component, element of construction, or any combination
of these. It may also be a sensor which is used to simulate the behaviour of a product.
3.25
uncontrolled fire
fire which spreads uncontrolled in time and space
4 Summary of test methods
This summary does not replace published standards which are the only valid reference
documents.
– 10 – TR 60695-8-2 © IEC:2008
4.1 Measurement of complete combustion
4.1.1 The bomb calorimeter
4.1.1.1 Test method
ISO 1716 [3]
4.1.1.2 Purpose and principle
The purpose of the method is to measure the gross heat of combustion at constant volume. A
test specimen of specified mass is burned under standardized conditions, at constant volume,
in an atmosphere of oxygen, in a sealed calorimeter calibrated by combustion of certified
benzoic acid. The heat of combustion determined under these conditions is calculated on the
basis of the observed temperature rise, taking into account heat loss and the latent heat of
vaporization of water.
4.1.1.3 Test specimen
The test specimen is typically a mixture of 0,5 g of finely powdered benzoic acid and, also in a
finely divided state, 0,5 g of the material under test.
4.1.1.4 Test method
The “bomb” is a central vessel that is sufficiently strong to withstand high pressures so that its
internal volume remains constant. The bomb is immersed in a stirred water bath, and the
combination of bomb and water bath is the calorimeter. The calorimeter is also immersed in an
outer water bath. During a combustion reaction, the temperature of the water in the calorimeter
and in the outer water bath is continuously monitored and adjusted by electrical heating to the
same value. This is to ensure that there is no net loss of heat from the calorimeter to its
surroundings, i.e. to ensure that the calorimeter is adiabatic.
To carry out a measurement, a test specimen, consisting of a known mass of benzoic acid
mixed with a known mass of test material, is placed in a crucible inside the bomb in contact
with an electrical ignition wire. The vessel is filled with oxygen under pressure (3,0 MPa to
3,5 MPa), sealed and allowed to attain thermal equilibrium. The sample is then ignited using a
measured input of energy. Combustion is complete because it takes place in an excess of high
pressure oxygen. The heat released is calculated from the known heat capacity of the
calorimeter and the rise of temperature that occurs as a result of the combustion reaction.
The experiment gives the heat released at constant volume, i.e. the change in internal energy,
ΔU. The gross heat of combustion at constant pressure is the enthalpy change, ΔH, where
ΔH = ΔU + Δ(PV)
Δ(PV) is calculated using the ideal gas law;
-1 -1
8,314 J⋅K ⋅mol ]
Δ(PV) = Δ(nRT) [R =
In order to calculate ΔH, it is necessary to be able to define the nature of the combustion
reaction, i.e. to know the chemical composition of the combustion products. This will not always
be known. However, the difference between ΔU and ΔH is normally small and can be ignored
for most fire science purposes. For example, in the case of carbon burning to form carbon
dioxide.
-1 -1
ΔU = -32,76 kJ⋅g and ΔH = -32,97 kJ⋅g .

TR 60695-8-2 © IEC:2008 – 11 –
The net heat of combustion can be calculated if the hydrogen content of the test specimen is
known. It is assumed that all the hydrogen is converted into water and the calculation uses a
-1
value of 2,449 kJ⋅g for the latent heat of vaporization of water at 25 °C.
4.1.1.5 Repeatability and reproducibility
An interlaboratory exercise was conducted by CEN/TC 127 and the results are summarized in
Annex B of ISO 1716 [3].
4.1.1.6 Relevance of test data
When measuring the heat of combustion in an oxygen bomb calorimeter, the entire sample is
completely converted to fully oxidized products. In fires this is rarely the case because some
potentially combustible material is often left as char and products of combustion are often only
partly oxidized, for example, soot particles in smoke, and carbon monoxide. Heat release in a
fire will therefore normally be less than the theoretical maximum that can be calculated from
heat of combustion data.
Heat of combustion data are fundamental to the science of thermochemistry and are of great
importance in fire modelling and fire safety engineering.
In Europe, under the Construction Products Directive [4], materials are classified as non-
-1
combustible if they have a gross heat of combustion of less than 2 kJ⋅g as measured in a
bomb calorimeter according to ISO 1716.
4.2 Measurements of incomplete combustion
4.2.1 Cone calorimeter
4.2.1.1 Test methods
See ISO 5660-1 [5] and ASTM E1354 [6]
4.2.1.2 Purpose and principle
This small-scale test method for determining heat release is based on the oxygen consumption
technique. It incorporates a load cell for mass loss determinations, a test specimen holder, a
conical heater for applying a uniform flux to the test specimen surface and oxygen consumption
measurement equipment.
This test method provides measurements of the rate of heat release, including peak and
average values, total heat release, effective heat of combustion, mass loss, time to ignition and
smoke obscuration. The exposures are made with and without spark ignition.
-2 -2
The external heat flux may be varied from 0 kW⋅m to 100 kW⋅m .
4.2.1.3 Test specimen
The specimen holder can accommodate test specimens up to 100 mm by 100 mm by 50 mm
thick. The normal orientation is horizontal, but vertical specimen holders also permit exposure
in a vertical orientation.
NOTE Although wires and cables can be installed in the test specimen holder and tested, no relationship to large-
scale tests has been confirmed.

– 12 – TR 60695-8-2 © IEC:2008
4.2.1.4 Test method
During the test, a test specimen is exposed to a specified radiant flux from an electrical conical
heater. Piloted ignition is achieved by using an external spark, which is moved over the test
specimen until ignition occurs. The heat release rate is assessed by measuring the oxygen
concentration in the exhaust duct and by using the principle of oxygen consumption (see
Subclause 4.1 and IEC 60695-8-1).
4.2.1.5 Repeatability and reproducibility
Interlaboratory evaluation tests have been conducted on building products and on plastic
materials. Details are available in ASTM RR E05-1008 [7].
Other interlaboratory evaluation tests have been conducted on building products and plastic
materials (see Clauses B.1 to B.3 of ISO 5660-1 [5]) and on plastic materials which intumesce
under heat exposure (see ISO 5660-1, Clause B.4).
No interlaboratory evaluation data are currently available on electrotechnical products.
ASTM D6113 [8] has been published as a test method on wires and cables.
4.2.1.6 Relevance of test data
Data obtained from these tests may be used as input to evaluate the contribution to the overall
fire hazard, as input into fire safety engineering calculations, and for research and product
development.
It should be noted that the testing of test specimens takes place in well ventilated conditions.
4.2.2 The Ohio State University calorimeter
4.2.2.1 Test method
See ASTM E906 [9].
4.2.2.2 Purpose and principle
This test method provides measurements of the rate of heat release based on the temperature
measurement technique. It includes peak and average values, total heat release, time to
ignition and smoke obscuration from materials and products.
The test specimens are exposed to radiant energy, with or without piloted ignition via a small
flame.
-2 -2
The external heat flux may be varied from 0 kW⋅m to 100 kW⋅m .
4.2.2.3 Test specimen
The test specimen holder can accommodate test specimens up to 150 mm by 150 mm by
50 mm thick. The normal orientation is vertical, but horizontal specimen holders also permit
exposure in a horizontal orientation.

TR 60695-8-2 © IEC:2008 – 13 –
4.2.2.4 Test method
The test specimen is placed in a test chamber through which there is a constant air flow. The
surface of the test specimen is exposed to a radiant energy source. Combustion may be
initiated by non-piloted or piloted ignition of the gases evolved.
The changes in temperature of the gases leaving the chamber are continuously monitored and
the heat release rate is calculated from these data.
4.2.2.5 Repeatability and reproducibility
Data have been obtained by the ASTM Task Group for Ohio State University RHR Calorimetry,
refer to ASTM E-5.21.34.
4.2.2.6 Relevance of test data
Data from these tests may be used as input to evaluate the contribution to the overall fire
hazard, as input into fire safety engineering calculations and for research and product
development.
The test method is also used by the USA Federal Aviation Authority to assess the compliance
of aircraft cabin materials with Federal Aviation Regulations [10].
4.2.3 Vertical cable ladder tests
NOTE A summary and comparison of vertical cable ladder tests which incorporate heat release measurements is
given in Table 1.
4.2.3.1 ASTM and UL test methods
See ASTM D5537 [11] and UL 1685 [12].
4.2.3.1.1 Purpose and principle
These two test methods are substantially similar, but each contains two protocols. These test
methods are used to determine flame propagation, heat release rate and total heat release
from burning cables, and can also be used to assess smoke obscuration, mass loss and
combustion gas release.
The ignition source is a propane gas premixed burner, set at typically 20 kW, either
perpendicular to the vertical cable test specimen, or at an angle of 20° to the vertical. The
cables are mounted on a vertical ladder, in configurations and loadings that depend on the test
requirements.
4.2.3.1.2 Test specimens
The test specimens are manufactured lengths of cables 2,44 m in length.
4.2.3.1.3 Test method
The cables are mounted on a vertical ladder in an appropriate configuration. The propane gas
burner is placed near the bottom of the vertical cable ladder (at a different location in each
protocol). The heat release rate is determined by measuring the oxygen concentration, the flow
rate and the temperature in the exhaust duct, using the principle of oxygen consumption. The
smoke and combustion products released are also measured in the exhaust duct.

– 14 – TR 60695-8-2 © IEC:2008
4.2.3.1.4 Repeatability and reproducibility
No data are currently available.
A interlaboratory evaluation of the ASTM D5537 test method was initiated by ASTM committee
D09 on Electrical and Electronic Insulation, but was not completed.
4.2.3.1.5 Relevance of test data
Data from these tests may be used as input to evaluate the contribution of wires and cables to
the overall fire hazard, and as input to fire safety engineering calculations.
4.2.3.2 EN test method
See EN 50399 [13].
4.2.3.2.1 Purpose and principle
EN 50399 specifies the test apparatus and test procedures for the assessment of the reaction
to fire performance of cables. It was developed from the FIPEC research programme [14] in
response to the European Construction Products Directive (CPD) [4] to enable classification
under the CPD to be achieved.
The test method describes an intermediate scale fire test of multiple cables mounted on a
vertical cable ladder and is carried out with a specified ignition source to evaluate the burning
behaviour of such cables and enable a direct declaration of performance. The test provides
data for the early stages of a cable fire from ignition of cables. It addresses the hazard of
propagation of flames along the cable, the potential, by the measurement of the heat release
rate, for the fire to affect areas adjacent to the compartment of origin, and the hazard, by the
measurement of production of light obstructing smoke, of reduced visibility in the room of origin
and surrounding enclosures.
The following parameters may be determined during the test: flame spread, rate of heat
release, total heat release, rate of smoke production, total smoke production, fire growth rate
index, and the occurrence of flaming droplets/particles.

The apparatus is based upon that of EN 50266-1 [15] but with additional instrumentation to
measure heat release and smoke production during the test.
NOTE The IEC standard which corresponds to EN 50266-1 is IEC 60332-3-10 [16].
EN 50399 contains two protocols. In one protocol the flame ignition source has a mass flow of
-1 -1 -1 -1
propane of 442 mg⋅s ± 10 mg⋅s and the air flow is 1 550 mg⋅s ± 140 mg⋅s (a nominal
power of 20,5 kW). This is used for classifications B2 , C and D . In the other protocol, the
ca ca ca
-1 -1
flame ignition source has a mass flow of propane of 647 mg⋅s ± 15 mg⋅s and the air flow is
-1 -1
2 300 mg⋅s ± 140 mg⋅s (a nominal power of 30 kW). This is used for classification B1 .
ca
4.2.3.2.2 Test specimens
The test specimens are manufactured lengths of cables having a minimum length of 3,5 m. The
loading depends on the diameter of the cable. The spacing of the test specimens on the ladder
also depends on the diameter of the cable.

TR 60695-8-2 © IEC:2008 – 15 –
4.2.3.2.3 Test method
The cables are mounted on the front of a vertical ladder in the appropriate configuration. The
lower part of the cables extends approximately 50 cm under the burner. The heat release rate
is determined by measuring the oxygen concentration, the flow rate and the temperature in the
exhaust duct, using the principle of oxygen consumption (see 3.21).
3 -1 3 -1
The airflow through the test chamber is 8 m ⋅min ± 0,8 m ⋅min .
-1 -1
The volume flow rate in the exhaust duct is set to between 0,7 m³⋅s to 1,2 m³⋅s . This flow
rate is maintained during the test.
The test flame is applied for 20 min, after which it is extinguished. The air flow through the test
chamber is maintained for a further 30 s after which it is stopped.
In the case of testing for class B1 , a non-combustible calcium silicate board is placed behind
ca
the ladder.
4.2.3.2.4 Repeatability and reproducibility
A interlaboratory test to assess repeatability and reproducibility has been carried out during the
second quarter of 2007.
4.2.3.2.5 Relevance of test data
The test was developed in Europe in response to the European Construction Products Directive,
and is required for four of the classes defined by the European Commission [17]. Test data
allows member states of the EU to use, for the first time, a harmonized system for classifying
the reaction to fire performance of cables used in buildings.
It has been demonstrated [14] that the utilization of these additional measurement techniques,
proven for other standard tests, e.g. for building products, are appropriate for assessing the
reaction to fire performance of electric cables. These techniques include heat release and
smoke production measurements. Compared with existing test methods described in EN 50266
and the various parts of IEC 60332-3, they enable a more comprehensive assessment system,
which is both more precise and sensitive, and enables a wider range of fire performance levels.
4.2.4 SBI test
4.2.4.1 Test method
See EN 13823 [18].
4.2.4.2 Purpose and principle
The SBI test is a reaction to fire test for essentially flat building products (excluding flooring) in
which the product, in a corner configuration, is exposed to the radiation and flames from a
defined single burning item (SBI) modelled by a propane fuelled sand-box burner placed at the
bottom internal corner of the test specimen. The SBI test method is unsuitable for cables. A
note in the scope of the standard states that “The treatment of some families of products, e.g.
linear products (pipes, ducts, cables etc) can need special rules.”
The test specimen is mounted on a trolley that is positioned in a frame beneath an exhaust
system. The reaction of the test specimen to the burner is monitored instrumentally and
visually. Flame spread, heat release and smoke production are all measured.

– 16 – TR 60695-8-2 © IEC:2008
4.2.4.3 Test specimen
The corner test specimen consists of two wings (long and short) of maximum thickness
200 mm, mounted at 90 ° to each other. The short wing is 495 mm × 1 500 mm, and the long
wing is 1 000 mm × 1 500 mm. Calcium silicate backing board panels are used to back both
specimen wings. They are placed either directly against the free-standing test specimen or at a
distance from it.
Table 1 – Summary and comparison of vertical cable ladder tests
ASTM ASTM
D 5537 [11] D 5537 [11]
Protocol A Protocol B
EN 50399 [13]
UL 1685 [12] UL 1685 [12]
UL 1581-1160 UL 1581-1164
Protocol Protocol
a) a)
Burner power / kW (approx.) 21 21 20,5 or 30
Flame application time / min 20 20 20
457 mm 305 mm 600 mm
b)
Burner placement
76 mm in back 76 mm in front 75 mm in front
Angle of burner Horizontal Horizontal
20 ° upwards
Ladder length / m 2,44 2,44 3,5
Ladder width / m 0,305 0,3 0,5
Test specimen length / m 2,44 2,44 3,5 min
Width of test specimen / m Between 0,22 and
0,15 Front only 0,25 Front only
and mounting techniques 0,32 Front only
Cables to be bundled No If D < 13 mm
If D ≤ 5 mm
Test enclosure specified Yes Yes Yes
Test runs needed 1 1 1
c)
2,44 (UL)
1,805 (UL)
No requirements are
Maximum char length
given in the test
from bottom / m No requirement
No requirement
d)
method
(ASTM)
(ASTM)
Optional (UL) Optional (UL)
Heat release measurement  Mandatory
Mandatory (ASTM) Mandatory (ASTM)
a) Both UL 1685 and ASTM D 5537 contain 2 test protocols. Protocol A of ASTM D 5537 is equivalent
to the UL 1581-1160 protocol of UL 1685, and protocol B of ASTM D 5537 is equivalent to the
UL 1581-1164 protocol of UL 1685. ASTM D5424 [19] is the same as ASTM 5537 except that
smoke release is the mandatory measurement, and heat release, mass loss, toxic gases and char
length are optional measurements. In ASTM D5537, heat release, mass loss and char length are
mandatory, and smoke and toxic gases are optional measurements. ASTM fire test standards do
not contain pass/fail criteria. When a cable is tested to UL 1685 and meets the flame spread, heat
release and smoke release criteria, it is classified as a "limited smoke" cable.
b) Height above the bottom, and distance from the test specimen surface.
c) A maximum char length of 1,5 m is measured from the horizontal height line of the burner.
d) Requirements are given in Table 4 of the European Commission Decision 2006/751/EC [17].

TR 60695-8-2 © IEC:2008 – 17 –
4.2.4.4 Test method
The test specimen is exposed to the flames from a sand-box burner placed at the bottom of the
internal corner. The flames are obtained by combustion of propane gas giving a heat output of
30,7 kW ± 2,0.
Data are recorded over a time period of 26 min and the performance of the test specimen is
evaluated over an interval of 20 min within this time period. The performance parameters of the
test specimen are: heat release, smoke production, lateral flame spread, and falling flaming
droplets and particles.
The short period before ignition is used to measure the heat and smoke output of the burner,
using an identical auxiliary burner away from the test specimen.
An important heat release parameter, used for classification purposes, is the Fire Growth Rate
(FIGRA) index. This is defined as the maximum of the quotient HRR (t)/(t – 300 s), where
av
HRR (t) is the 30 s moving average of the heat release rate.
av
4.2.4.5 Repeatability and reproducibility
A interlaboratory test series was carried out in 1997. It was conducted by 15 laboratories,
testing 30 products three times. Results are given in Annex B of EN 13823.
A second interlaboratory test series was reported in January 2005 [20]. It was conducted by 30
European laboratories, testing 9 different construction products.
4.2.4.6 Relevance of test data
The test was developed in Europe in response to the European Construction Products Directive,
and is required for four of the classes defined by the European Commission. The test was
designed to predict performance in the full-scale test, ISO 9705 [21], which is the reference
scenario. Test data allow member states of the EU to use, for the first time, a harmonized
system for classifying the reaction to fire performance of construction products.
4.2.5 Horizontal cable ladder test
4.2.5.1 Test method
See EN 50289-4-11 [22].
4.2.5.2 Purpose and principle
The test method specifies a horizontal fire test method for the determination of flame
propagation distance, optical smoke density, total heat release, heat release rate, time to
ignition and flaming droplets/particles for communication cables. The cables are tested in a
representative installed condition.
The ignition source is a dual port methane gas diffusion flame burner, set at typically
88 kW ± 2 kW. The test flame extends downstream to a distance of 1,37 m over one end of the
test specimen, with negligible upstream coverage.

– 18 – TR 60695-8-2 © I
...