SIST EN 50399:2011

SLOVENSKI STANDARD
01-junij-2011
Skupne preskusne metode za ognjevzdržnost kablov - Meritve oddajanja toplote in
nastajanja dima na kablih med preskusom z razpršenim plamenom - Preskusna
naprava, postopki, rezultati
Common test methods for cables under fire conditions - Heat release and smoke
production measurement on cables during flame spread test - Test apparatus,
procedures, results
Allgemeine Prüfverfahren für das Verhalten von Kabeln und isolierten Leitungen im
Brandfall - Messung der Wärmefreisetzung und Raucherzeugung während der Prüfung
der Flammenausbreitung - Prüfeinrichtung, Prüfverfahren und Prüfergebnis
Méthodes d'essai communes aux câbles soumis au feu - Mesure de la chaleur et de la
fumée dégagées par les câbles au cours de l'essai de propagation de la flamme -
Appareillage d'essai, procédure et résultats
Ta slovenski standard je istoveten z: EN 50399:2011
ICS:
13.220.40 Sposobnost vžiga in Ignitability and burning
obnašanje materialov in behaviour of materials and
proizvodov pri gorenju products
29.060.20 Kabli Cables
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN 50399
NORME EUROPÉENNE
April 2011
EUROPÄISCHE NORM
ICS 13.220.40; 29.060.20
English version
Common test methods for cables under fire conditions -
Heat release and smoke production measurement on cables during flame
spread test -
Test apparatus, procedures, results

Méthodes d'essai communes aux câbles Allgemeine Prüfverfahren für das
soumis au feu - Verhalten von Kabeln und isolierten
Mesure de la chaleur et de la fumée Leitungen im Brandfall -
dégagées par les câbles au cours de Messung der Wärmefreisetzung und
l'essai de propagation de la flamme - Raucherzeugung während der Prüfung
Appareillage d'essai, procédure et der Flammenausbreitung -
résultats Prüfeinrichtung, Prüfverfahren und
Prüfergebnis
This European Standard was approved by CENELEC on 2011-02-28. CENELEC members are bound to comply
with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard
the status of a national standard without any alteration.

Up-to-date lists and bibliographical references concerning such national standards may be obtained on
application to the Central Secretariat or to any CENELEC member.

This European Standard exists in three official versions (English, French, German). A version in any other
language made by translation under the responsibility of a CENELEC member into its own language and notified
to the Central Secretariat has the same status as the official versions.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus,
the Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy,
Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia,
Spain, Sweden, Switzerland and the United Kingdom.

CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung

Management Centre: Avenue Marnix 17, B - 1000 Brussels

© 2011 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 50399:2011 E
Foreword
This European Standard was prepared by the Technical Committee CENELEC TC 20, Electric cables.
The text of the draft was submitted to the formal vote and was approved by CENELEC as EN 50399 on
2011-02-28.
The following dates were fixed:
– latest date by which the EN has to be implemented
at national level by publication of an identical
national standard or by endorsement (dop) 2012-02-28

– latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2014-02-28
__________
– 3 – EN 50399:2011
Contents
Introduction . 5
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 7
4 Test apparatus . 8
4.1 General . 8
4.2 Air input . 9
4.3 Hood . 9
4.4 Exhaust duct. 10
4.5 Instrumentation in the exhaust duct . 10
4.6 Extracting ventilator . 11
4.7 Smoke production measuring equipment . 11
4.8 Combustion gas analysis equipment . 12
5 Qualification of test apparatus . 12
5.1 General . 12
5.2 Flow distribution measurements . 12
5.3 Sampling delay time measurement . 13
5.4 Commissioning calibrations . 13
5.5 Routine calibration . 13
6 Test procedure. 14
6.1 Initial test conditions . 14
6.2 Test sample . 14
6.3 Sample conditioning . 14
6.4 Determination of the number of test pieces . 15
6.5 Mounting of the test sample . 16
6.6 Exhaust volume flow . 17
6.7 Ignition source . 17
6.8 Flame application time . 17
6.9 Testing operations . 18
6.10 Observations and measurements during the test . 18
7 Determination of parameters derived from the test . 19
7.1 Calculation of HRR and SPR parameters . 19
7.2 Determination of extent of flame spread (FS) . 19
8 Test report . 20
8.1 General . 20
8.2 Contents . 20
Annex A (normative) Calculation of heat release . 31
A.1 Volume flow . 31
A.2 Generated heat effect . 31
A.3 Calculation of the mole fraction of water vapour in the air . 33
Annex B (normative) Smoke production . 34
Annex C (informative) Additional information on Reynolds number in Figure 5 . 35

Annex D (normative) Flow distribution inside the duct . 36
D.1 General . 36
D.2 Velocity profile factor k . 36
c
Annex E (normative) Commissioning calibrations . 39
E.1 General procedures for separate pieces of equipment . 39
E.2 Gas analyser calibrations . 39
E.3 HRR calibrations . 40
E.4 Smoke measurement system calibration . 44
Annex F (informative) Guidance for calibration procedures for specific measuring equipment . 47
F.1 General procedures for separate pieces of equipment . 47
F.2 Gas analyser calibrations . 47
F.3 Check of propane mass flow controller or rotameter . 47
F.4 Optical filter check for white light systems . 48
Annex G (normative) Calculation of HRR , SPR and FIGRA . 49
av av
G.1 Calculation of HRR . 49
av
G.2 Calculation of SPR . 50
av
G.3 Calculation of the Fire Growth Rate Index (FIGRA) . 50
Annex H (informative) Guidance on the choice of test equipment . 51
Annex I (informative) Guidance on the file format for data from the test . 52
Bibliography . 56

Figures
Figure 1 – General arrangement of test apparatus . 22
Figure 2 – Schematic of a hood . 23
Figure 3 – Typical guide vanes . 24
Figure 4 – Bidirectional probe . 25
Figure 5 – Probe response versus Reynolds number . 26
Figure 6 – Sampling probe . 27
Figure 7 – Schematic diagram of sampling line . 28
Figure 8 – Optical system – General arrangement . 29
Figure 9 – Mounting arrangement for Class B1 . 30
ca
Figure D.1 – Section of the exhaust duct – Positions for measurement of the gas velocity . 37
Figure E.1 – Overview of commissioning calibrations . 46

Tables
Table 1 – Mounting as a function of cable diameter . 17
Table E.1 – Burner ignition times and HRR levels . 41
Table E.2 – Example of determination of commissioning k factor . 43
t
Table I.1 - Example of the recommended raw data file format . 53

– 5 – EN 50399:2011
Introduction
EN 50399 specifies the test apparatus and test procedures for the assessment of the reaction to fire
performance of cables to enable classification under the Construction Products Directive [1] 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 under defined conditions during the test:
a) flame spread;
b) heat release rate;
c) total heat release;
d) smoke production rate;
e) total smoke production;
f) fire growth rate index;
g) occurrence of flaming droplets/particles .
The apparatus is based upon that of EN 60332-3-10 but with additional instrumentation to measure heat
release and smoke production during the test. It has been demonstrated [3] that the utilisation 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 60332-3-10, they enable a more comprehensive assessment system, which is both more precise and
sensitive, and enables a wider range of fire performance levels.
Care should be exercised in relating the parameters measured to different safety levels in actual cable
installations as the actual installed configuration of the cables may be a major determinant in the level of
flame spread, heat release and smoke production occurring in an actual fire. These parameters depend
upon a number of features, such as
a) the volume of combustible material exposed to the fire and to any flaming or heat which may be
produced by the combustion of the cables;
b) the geometrical configuration of the cables and their relationship to an enclosure;
c) the temperature at which it is possible to ignite the gases emitted from the cables;
d) the quantity of combustible gas released from the cables for a given temperature rise;
e) the volume of air passing through the cable installation;
f) the construction of the cable, e.g. armoured or unarmoured, multi or single core.
All of the foregoing assumes that the cables are able to be ignited when involved in an external fire.

The conditions of cable mounting, including volume of material exposed and geometrical configuration of
the cables on the test ladder, and volume of airflow through the chamber have been chosen to be in
accordance with that required by the Commission Decision 2006/751/EC [2]. CENELEC has not been
involved in the definition of these parameters. These standardised conditions provide the basis for
classification but do not necessarily correspond to conditions found in a particular cable installation.
NOTE  Further information on the use of standardised conditions for classification with respect to product end-use application may
be found in European Commission Guidance Paper G [4].
EN 50399 gives details of the apparatus to be used in conjunction with the equipment described in
EN 60332-3-10 in order to carry out the measurement of heat release and smoke production during the
test. Details of the test procedures are also given.

– 7 – EN 50399:2011
1 Scope
EN 50399 specifies the apparatus and methods of test for the assessment of vertical flame spread, heat
release, smoke production and occurrence of flaming droplets/particles of vertically-mounted bunched
wires or cables, electrical or optical, under defined conditions.
NOTE  For the purpose of this standard the term "electric wire or cable" covers all insulated metallic conductor cables used for the
conveyance of energy or signals.
EN 50399 details the apparatus and the arrangement and calibration of the instrumentation to be installed
in order to measure the heat release and the smoke production during the test. The combustion gases are
collected in a hood above the test chamber and conveyed through an exhaust system, which allows the
measurement of heat release rate and smoke production. Test procedures to be used for type approval
testing for classification of cables in Euroclasses B1 , B2 , C and D are given. Cable installation on
ca ca ca ca
the test ladder and the volume of air passing through the chamber are in accordance with the Commission
Decision 2006/751/EC [2] which is reflected in the requirements of this standard.
The apparatus described in this standard shall be used in conjunction with that described in
EN 60332-3-10.
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.
EN 60332-3-10, Tests on electric and optical fibre cables under fire conditions –
Part 3-10: Test for vertical flame spread of vertically-mounted bunched wires or cables – Apparatus
(IEC 60332-3-10)
EN 60584-1, Thermocouples – Part 1: Reference tables (IEC 60584-1)
EN ISO 13943:2010, -Fire safety – Vocabulary (ISO 13943:2008)
ISO 3966, Measurement of fluid flow in closed conduits – Velocity area method using Pitot static tubes
3 Terms and definitions
For the purpose of this document, the terms and definitions given in EN ISO 13943:2010 and the following
apply.
3.1
heat release rate
HRR
thermal energy released per unit time by an item during combustion under specified conditions
3.2
total heat release
THR
integrated value of the heat release rate over a defined period
3.3
smoke production rate
SPR
smoke production per unit time

3.4
total smoke production
TSP
integrated value of the smoke production rate over a defined period
3.5
flame spread
FS
propagation of a flame front
NOTE  In this standard the extent of flame spread is determined as the extent of damage measured by the onset of char.
3.6
fire growth rate index
FIGRA
highest value of the quotient between HRR and time
NOTE 1  In this standard FIGRA is expressed in W/s.
NOTE 2  Details of the calculation of FIGRA are given in Annex G.
3.7
flaming droplets/particles
material separating from the specimen during the test and continuing to flame for a minimum period as
described in this test method
3.8
E-value
heat release per volume of oxygen consumed
4 Test apparatus
4.1 General
The test apparatus shall consist of the test chamber, standard ladder and ignition source, as described in
EN 60332-3-10, with the additional features as specified in 4.2 to 4.8. Figure 1 shows a schematic
diagram of the apparatus. The ignition source shall be one ribbon-type propane gas burner. The ladder
shall be the standard ladder of (500 ± 5) mm width. The air supply shall be a system that blows air into the
chamber at an airflow rate of (8 000 ± 400) l/min.
The additional features of the apparatus shall be capable of measuring the following parameters:
a) oxygen consumption;
b) CO production;
c) volume flow in the exhaust duct;
d) smoke production.
WARNING  Care should be taken in monitoring and extinguishing cable fires once the test specimen has
started to propagate fire. Some specimens may have a very high capacity to generate high heat release
levels that could damage the test equipment and instrumentation. It is important that testing staff are
sufficiently trained in dealing with such fires and have adequate fire fighting facilities at their disposal
during testing.
NOTE 1  It is recommended that indicative temperature measurements are taken through the use of thermocouples installed along
the cable bunch being tested at 1,5 m and 2,5 m above the burner and at the top of the chamber or in the duct. Such
measurements can give an early indication of any excessive temperature or burning condition that may require the test to be
aborted in order to prevent damage to the test equipment.

– 9 – EN 50399:2011
All data shall be measured and recorded every 3 s. These point measurements shall be averaged over a
period of 30 s for parameters relating to heat release and 60 s for parameters relating to smoke
production, in order to provide the required data. The data shall be processed according to the
requirements of this standard.
NOTE 2  It is necessary to produce the average measurement in order to damp the variability caused by frequent point
measurement.
The additional features and their associated measurements shall allow for calculation of the following:
a) heat release (see Annex A);
1) heat release rate (HRR);
2) total heat release (THR);
3) fire growth rate index (FIGRA);
b) smoke production (see Annex B);
1) smoke production rate (SPR);
2) total smoke production (TSP).
4.2 Air input
Air shall be introduced to the test chamber through a plenum box fitted directly underneath, and of
approximately the same dimensions as, the air inlet aperture. The depth of the plenum box shall be
(150 ± 10) mm. Air shall be blown into the plenum box from a fan through a rectangular straight section of
duct of constant cross section of (300 ± 10) mm width and (80 ± 5) mm height and a minimum length of
800 mm, which shall enter from the rear of the chamber and be parallel to the floor and along the burner
centre line as shown in Figure 1. The duct shall be arranged to inlet air to the plenum box through an
aperture in the longest side, centred horizontally and such that the bottom of the duct shall be no greater
than 10 mm above the bottom of the plenum box. A grid shall be fitted in the air inlet aperture to achieve
uniform flow of the air. The grid shall be constructed of steel plate approximately 2 mm thick with holes of
approximately 5 mm diameter drilled at approximately 8 mm spacing between centres.
The airflow rate shall be measured in a circular duct prior to the rectangular cross section duct. It shall be
measured by a gas flow measuring device located at a straight section of the circular duct. The minimum
length of straight circular section before and after the measuring device shall be selected according to the
technical specification of the measuring device.
NOTE 1  A fluid flow measuring system according to either EN ISO 5167-2 (orifice plate) or EN ISO 5167-4 (Venturi tube) is
recommended. Alternatively, a Pitot tube taking multiple samples across the section of the duct and averaging to account for
variations across the section or a hot wire anemometer measuring at multiple positions across the section of the duct as described
in Annex D may be used.
The airflow shall be set prior to a test at (8 000 ± 400) l / min and shall not be changed during the test. The
airflow shall be checked throughout the test and shall not vary by more than 10 % of the set value.
NOTE 2  This information does not need to be recorded.
4.3 Hood
A hood (see Figure 2) having a truncated shape, and where the base has a minimum length of 1,50 m and
a minimum width of 1,00 m, shall be centred above the outlet of the test chamber. The base of the hood
shall be raised above the top of the test chamber, with the largest side of the hood parallel to the largest
side of the outlet of the chamber.
NOTE 1  A gap of approximately 200 mm to 400 mm between the top of the test chamber and the base of the hood has generally
been found suitable.
There shall be a chamber above the hood to allow a connection to the exhaust duct.
NOTE 2  Plates/baffles may be installed in the hood to improve mixing of the air / effluents.
The system shall be designed to collect all the combustion products leaving the test chamber through the
outlet during the test. There shall be no leakage of flames or smoke. The exhaust capacity shall be at

least 1 m³/s at normal pressure and a temperature of 25 °C. The exhaust system design shall not be
based on natural convection.
NOTE 3  In order to extract all gases and vapours, especially in the case of heavily burning cables, or cables which require to be
specially extinguished and produce high volumes of gases and vapours, an exhaust system with a capacity of 1,5 m³/s is
recommended.
4.4 Exhaust duct
An exhaust duct shall be connected to the hood as described in 4.3. The inner diameter, D, of the duct
shall be in the range 250 mm to 400 mm. The straight section of the duct shall have a minimum length of
12 x D, such that a uniform flow profile is established at the point of measurement.
NOTE  A uniform flow profile can be obtained by introducing guide vanes (see Figure 3) before and after the measuring section
such as described in EN 14390. This is highly recommended in order to obtain as precise measurements as possible.
4.5 Instrumentation in the exhaust duct
4.5.1 Volume flow
The flow shall be measured by a bidirectional probe located at the centre line of the duct and at a
minimum distance from the beginning of the straight section of exhaust duct of 8 x D. The length of the
straight section of duct beyond the probe shall be at least 4 x D. The probe which is shown in Figure 4
consists of a stainless steel cylinder, 32 mm long and with an outer diameter of 16 mm. The cylinder is
divided into two equal chambers. The pressure difference between the two chambers shall be measured
by a pressure transducer. The plot of the probe response versus the Reynolds number is shown in
Figure 5 (see also Annex C).
The pressure transducer shall have a measuring precision better than ± 5 Pa. A suitable range of
measurement is 0 Pa to 200 Pa (when using duct diameters between 250 mm and 400 mm).
The two connection pipes between the bidirectional probe and the pressure transducer shall be of the
same length.
Gas temperature in the immediate vicinity of the probe shall be measured by a sheathed K type
thermocouple with a maximum diameter of 1,5 mm in accordance with EN 60584-1. The thermocouple
shall be positioned so that it does not disturb the flow pattern around the bidirectional probe.
NOTE  If more than one thermocouple is used then all thermocouples shall be of the same size and type.
4.5.2 Sampling probe
The sampling probe shall be located where the exhaust duct flow is well mixed. The probe shall have a
cylindrical form so that disturbance of flow is minimised. The gas samples shall be taken along the whole
diameter of the exhaust duct. Examples of suitable sampling probes are shown in Figure 6. The intake of
the sampling probe shall be turned downstream in order to avoid soot clogging in the probe. The sampling
probe shall be connected to the gas analysers for oxygen (O ) and carbon dioxide (CO ) by a suitable
2 2
sampling line.
4.5.3 Sampling line
The sampling line shall be manufactured from corrosion resistant material, e.g. PTFE. The combustion
gases shall be filtered with inert filters to the degree of particle concentration required by the gas analysis
equipment. The filtering procedure shall be carried out in more than one step. The system shall be
capable of removing water vapour.

– 11 – EN 50399:2011
The combustion gas shall be transported by a pump which does not emit oil, grease or similar products,
as these may contaminate the gas mixture.
NOTE  A membrane pump is suitable.
A pump capacity between 10 l/min and 50 l/min is recommended. The pump shall generate a pressure
differential of at least 10 kPa to reduce the risk of clogging of the filters by smoke.
The sampling line (see Figure 7) shall be connected at its end to O and CO analysers.
2 2
4.6 Extracting ventilator
At the end of the exhaust duct, an extracting ventilator shall be installed. A minimum exhaust capacity of
1,5 m³/s at normal pressure and at a temperature of 25 °C is recommended.
NOTE  Legal requirements may make it necessary for equipment for collecting and washing the effluent to be fitted to the test
chamber. This equipment shall be such as to collect all the effluents without causing a change in the air flow rate through the test
chamber.
4.7 Smoke production measuring equipment
4.7.1 General
The optical density of the smoke can be measured by two different measuring techniques as described in
4.7.2 and 4.7.3. Although the measurement principle differs for both systems, it has been shown that the
two different systems do not give substantially different results [3].
A general arrangement of an optical system is shown in Figure 8.
NOTE 1  Other systems may be used provided that their equivalence to those specified has been demonstrated.
NOTE 2  Based upon experience, white light systems are recommended.
The smoke production measuring equipment shall be located where the exhaust duct flow is well mixed.
4.7.2 White light system
A light attenuation system, of the white light type, mounted with a flexible connection to the side ducts of
the exhaust duct, shall consist of the following.
a) A lamp, of the incandescent filament type operating at a colour temperature of (2 900 ± 100) K.
The lamp shall be supplied with stabilized direct current, stable within 0,5 % (including temperature,
short-term and long-term stability).
b) A lens system, to align the light to a parallel beam and with a diameter of at least 20 mm.
The photocell aperture shall be placed at the focus of the lens in front of it and it shall have a
diameter, d, chosen with regard to the focal length of the lens, f, so that d/f is less than 0,04.
c) A detector, with a spectrally distributed responsivity agreeing with the CIE V(λ) function (CIE photopic
curves) to an accuracy of within ± 5 %. The detector output shall, over an output range of at least two
decades, be linear within 3 % of the measured transmission value or 1 % of the absolute
transmission.
Calibration of the light attenuation system shall be carried out according to E.4. The 90 % response time
of the system shall be not more than 3 s.
Air may be introduced in the side ducts so that the optics stay clean, within the given light attenuation drift
requirements (see E.4.2). Pressurized air can be used instead of a self suction system.

4.7.3 Laser light system
A laser photometer system shall use a helium-neon laser with a power output between 0,5 mW and
2,0 mW.
Air may be introduced in the side ducts so that the optics stay clean, within the given light attenuation drift
requirements (see E.4.2). Pressurized air may be used instead of a self suction system.
NOTE The optics should be regularly inspected and cleaned from smoke deposition whenever necessary.
4.8 Combustion gas analysis equipment
4.8.1 General
The analysis of oxygen, and carbon dioxide, requires that any water vapour in the combustion gases shall
be trapped by means of a suitable drying agent.
4.8.2 Oxygen
The analyser shall be of the paramagnetic type and capable of measuring a range of 16 % to 21 %
oxygen (V /V ). The noise and drift of the analyser shall be not more than 0,01 % (100 parts per million)
O air
over a period of 30 min as measured in accordance with E.2.3. The manufacturer’s declared response
time of the analyser shall be not more than 12 s. The output from the analyser to the data acquisition
system shall have a resolution better than 0,01 % (100 parts per million).
4.8.3 Carbon dioxide
Continuous analysis of carbon dioxide shall be achieved using an IR spectrometer. The analyser shall be
capable of measuring a maximum range of 0 % to 10 % carbon dioxide. The linearity of the analyser shall
be 1 % of full scale or better and the manufacturer’s declared response time shall be not more than 12 s.
5 Qualification of test apparatus
5.1 General
The checks in 5.2 to 5.5 shall be undertaken to qualify the apparatus.
NOTE  In this document, the use of the terminology “calibration” mirrors that in EN 13823 (the SBI test). It is used in a generic
way, in some cases referring to a true calibration procedure whilst in others referring to a series of checks which may, in other
documents, be referred to as a verification.
5.2 Flow distribution measurements
The determination of the flow profile in the exhaust duct, in the vicinity of the probes, is required for two
main reasons:
a) to check that the design of the exhaust duct gives an acceptable profile;
b) to determine a k which shall be compared with the k obtained by the following calibrations.
c t
Further information on how to perform this measurement is given in Annex D.
NOTE  The value k should be approximately 0,86 for a 400 mm duct.
c
Measurements shall be performed by means of a calibrated hot wire anemometer (or other suitable
instrument) moved along a vertical axis (OY) and then along a horizontal axis (OX) to obtain the vertical
and horizontal air speed distributions inside the duct.
The velocity profile shall be measured at the same airflow rate as used during the actual test (see 6.6).
Measurements at additional flow settings should be made and used to demonstrate the consistency of the
velocity profile determination within the range of operation.

– 13 – EN 50399:2011
5.3 Sampling delay time measurement
Gas analysers take a finite time to respond to changes in gas concentrations. This is called the sampling
delay time. The delay times shall be determined in order to synchronise the temperature, oxygen and
carbon dioxide measurements. All data shall be corrected for any delay time before calculating the heat
release. The delay time of the oxygen analyser shall be determined as the time difference between a 3 K
change in the duct temperature and a 0,05 % change in the oxygen concentration. The delay time of the
carbon dioxide analyser shall be determined as the time difference between a 3 K change in the duct
temperature and a 0,02 % change in the carbon dioxide concentration.
Sampling delay times shall be determined before commissioning the apparatus and after each major
change in the gas analysis system.
5.4 Commissioning calibrations
Before initial use of the apparatus and after each major change in the gas analysis system, exhaust flow
measurement, gas and airflow measurement to the burner or smoke measurement, a series of
calibrations shall be performed in order to
a) check the equipment, including any improvements adopted during the set-up stage or modification
period;
b) determine a commissioning k factor to be used for daily testing;
t
c) check the stability of the smoke measurement system;
d) check the correct measurement of the white light measuring system.
The calibrations shall be carried out at different levels of HRR covering the range of heat releases that are
expected when burning cables in a test, i.e. from about 20 kW to 200 kW. This is required in order to
verify the linearity of the HRR measurement system. Further information on the HRR calibration and
determination of the commissioning k factor is given in Annex E.
t
The procedure given in Annex E shall be carried out and its requirements met in order to calibrate and
check the smoke measuring system.
NOTE  It is recommended that the commissioning calibrations are carried out at least once per year depending on the frequency of
use of the equipment.
5.5 Routine calibration
5.5.1 General
Each testing day a calibration test shall be performed using the ignition source given in EN 60332-3-10.
A calibration burn of at least 10 min shall be performed, using the heat output of the burner relevant to the
test procedure to be used that day (i.e. 20,5 kW or 30,0 kW as appropriate). The calibration test shall be
carried out without the ladder in the test chamber. The result of the calibration test shall be recorded for
each testing date. Testing shall not be carried out unless the criteria given in 5.5.4 are met.
NOTE  See E.2.2 and E.2.4 for the daily adjustment of the oxygen and carbon dioxide analysers
5.5.2 Procedure
The calibration shall be performed in the following sequence:
a) a 5 min base line without the burner;
b) a further 10 min with the burner at the relevant heat output;
c) a further 5 min without the burner.

5.5.3 Calculations
The following shall be calculated after the calibration test using the commissioning k factor and the
t
E-value for propane (16,8 MJ/m ):
a) the drift of the HRR, oxygen % and light intensity during the first 5 min;
b) the average calculated HRR during the last 5 min of the burning period;
c) the start values of oxygen %, carbon dioxide %, light intensity and HRR, each as the average during
the first minute of the 5 min base line period;
d) the end values of oxygen %, light intensity and HRR, each as the average during the last minute of
the calibration test;
e) the difference between start and end values of oxygen %, HRR and light intensity.
5.5.4 Criteria
a) the average HRR during the last 5 min of the burner period shall be within ± 5 % of the set value of
20,5 kW or 30,0 kW;
b) the difference between the start and end values of oxygen % shall be less than 0,01 % (absolute
value);
c) the difference between the start and end values of light intensity shall be equal to or less than 1 %
transmission;
d) the difference between the start and end values of HRR shall be equal to or less than 2 kW;
e) the drift on the light intensity shall be less than 1 % during the 5 min before burner ignition;
f) the drift of oxygen % shall be less than 0,01 % (absolute value) during the 5 min before burner
ignition;
g) the drift on HRR measurement shall be less than 2,0 kW during the 5 min before burner ignition.
NOTE  The drift of oxygen %, HRR and light intensity shall be calculated by means of a linear trend line during the 5 min before
burning ignition.
6 Test procedure
6.1 Initial test conditions
The test chamber and air supply temperature shall be in the range 5 °C to 40 °C.
6.2 Test sample
The test sample shall comprise a number of test pieces of cable from the same production length, each
+0,1
having a length of (3,5 ) m. The number of test pieces in the test sample shall be as determined
according to 6.4.
6.3 Sample conditioning
The test pieces shall be conditioned for at least 16 h at a temperature of (20 ± 10) °C. All packaging shall
be removed prior to conditioning. The test pieces shall be dry.

– 15 – EN 50399:2011
6.4 Determination of the number of test pieces
6.4.1 General
The following formulae shall be used to determine the number of test pieces (N) for the test.
NOTE  The following formulae apply to circular cables. No mounting procedure for non circular cables has been defined. This is
under consideration.
6.4.2 Cables with a diameter greater than or equal to 20,0 mm
The number of test pieces, N, is given by
 
300+ 20
 
N = int (1)
 
d + 20
 c 
where
d is the measured diameter of the cable (in mm and rounded to the nearest mm
c
according to IEC rules);
int function the integer part of the result (i.e. the value rounded down).
6.4.3 Cables with a diameter greater than 5,0 mm but less than 20,0 mm
The number of test pieces, N, is given by
 
300+ d
c
N = int  (2)
 
2d
 c 
where
d is the measured diameter of the cable (in mm and rounded to the nearest mm
c
according to IEC rules);
int function the integer part of the result (i.e. the value rounded down).
6.4.4 Cables with a diameter less than or equal to 5,0 mm
A number of approximately 10 mm diameter bundles (N ) shall be mounted where
bu
300+10
 
N = int =15 (3)
 
bu
 
Thus 15 bundles shall be mounted.
The number of test pieces in each bundle (n) is:
 
 
n= int (4)
 2
d
 c 
where
d is the measured diameter of the cable (in mm to one decimal place);
c
int function the integer part of the result (i.e. the value rounded down).

The total number of test pieces (N) will thus be:
N = n×15 (5)
6.5 Mounting of the test sample
6.5.1 Mounting of the test sample for all classes
The test sample shall be mounted on
...