IEC 60332-3-21:2000 pdf download

IEC 60332-3-21:2000 pdf download.Tests on electric cables under fire conditions -Part 3-21: Test for vertical flame spread of vertically mountedbunched wires or cables – Category A F/R.
3 Definitions
For the purposeof this part of lEG 60332 the following definitions apply. The definitions are
taken from IEC 60695-4.
3.1
ignition source
source of energy that initiates combustion
3.2
char
carbonaceous residue resulting from pyrolysis or incomplete combustion
3.3
flame spread
propagation of a flame front
4 Test apparatus
4.1 General
The apparatus specified In IEC 60332-3-10 shall be used.
4.2 IgnItion source
The ignition source shall be one ribbon-te propane gas burner as specified in IEC 60332-3-10.
5 Test procedure
5.1 Test sample
The test sample shall comprise a number of test pieces of cable from the same production length, each having a minimum length of 3,5 m.
The total number of test pieces in the test sample shall be that number required to provide a nominal total volume of non-metallic material of 7 I/rn of test sample.
The test sample shall be chosen within the limitations given in annex A.
The test pieces forming the test sample shall be conditioned at a temperature of (20 ± 10) °C for at least 16 h before commencing the test. The test pieces shall be dry.
5.2 Determination of the number of test pieces
In order to calculate the appropriate number of test pieces, it is necessary to determine the volume per metre of non-metallic material of one test piece.
The completed test sample shall be mounted such that
— the space between each test piece of one layer (front or rear) shall be 0,5 times the cable diameter, but not exceeding 20 mm;
— the maximum width of a single layer shall be 300 mm;
— the minimum distance between the sample edge and the inside of the ladder upright shall be 50 mm;
— test pieces mounted on the rear of the ladder shall be centred relative to the space between pieces on the front of the ladder;
— the completed array of test pieces is approximately centred on the ladder.
Figure 1 illustrates the arrangement.
5.4 Flame application time
The test flame shall be applied for 40 mm, after which it shall be extinguished. The air flow rate through the test chamber shall be maintained until cable burning or glowing has ceased, or until a maximum duration of I h, after which any remaining cable burning or glowing shall be extinguished.
6 EvaluatIon of test re8ults
After all cable burning or glowing has ceased or been extinguished, the test sample shall be wiped clean.
All soot is to be ignored if, when wiped off, the original surface is undamaged. Softening or any deformation of the non-metallic material is also to be ignored. The flame spread shall be measured as the extent of the damage. It shall be measured in metres to two decimal places from the bottom edge of the burner to the onset of char. The onset of char is determined as follows:
press against the cable surface with a sharp object, for example a knife blade. Where the surface changes from a resilient to a brittle (crumbling) surface, this indicates the onset of char.
7 Performance requirements
The performance requirements for a particular type or class of wire or cable should preferably be given in the individual cable standard. In the absence of any given requirements, the recommended performance requirements given in annex B should be used.
8 Retest procedure
In case of dispute, two further tests shall be undertaken as detailed in clause 5. The test shall be deemed as satisfactory if both tests meet the stated requirement.
Test report
The test report shall include the following information:a)full description of the cable tested;
b)manufacturer of the cable tested;
c)the part of the standard against which the test was carried out;the number of test pieces;
d)the total volume of non-metallic material, per metre of test sample, of the test pieces;f). e)the method of mounting, i.e. spaced;
g)the number of layers and number of test pieces in each layer;h)flame application time (i.e. 40 min);
i)the number of burners (i.e. one);jthe extent of damage;
k)the time to extinction of all burning or glowing.