IEC 60332-3-21:2018 covers category A F/R for methods of test for the assessment of vertical flame spread of vertically-mounted bunched wires or cables, under defined conditions. This document relates only to power cables of conductor cross-sectional area greater than 35 mm2 installed on the test ladder in a spaced configuration on the front and rear to achieve a nominal total volume of non-metallic material of 7 l/m of test sample. The flame application time is 40 min. This method of mounting is intended for special cable designs used in particular installations when required in the cable specification. Category A F/R is not intended for general use. The test is intended for type approval testing. The requirements for the selection of cables for testing are given in Annex A. The flame spread is measured as the extent of damage of the cable sample. This procedure can be used to demonstrate the cable’s ability to limit flame spread. A recommended performance requirement is given in Annex B.^This second edition cancels and replaces the first edition published in 2000. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition:
a) adjustments have been made to the title, and elsewhere, to emphasise the standard is applicable to optical fibre cables as well as metallic conductor types;
b) details of the way in which cables are mounted on the ladder have been better defined in order to improve repeatability and reproducibility.
It has the status of a group safety publication in accordance with IEC Guide 104.