What are fire performance tests?

There are several different fire performance tests for cables. The purpose of the test is to verify that the cable will continue to maintain electrical continuity or functionality for a defined period of time in a simulated fire condition. These cables are used to provide power to fire survival equipment, fire alarms and emergency lighting etc.

BS6387 - British fire performance test

One of the longest established British Standards for fire performance testing is BS 6387. This covers cables with a diameter of up to 20mm. The standard describes three which the cable must pass, C, W and Z. The tests are conducted on a special fire test rig and the cable is energised to 600V. The cables electrical continuity is indicated by a series of light bulbs which are connected through fuses. A failure will be indicating by the fuse blowing and the light failing on one or more of the bulbs.

The test parameters are as follows and each test is conducted separately.

Test	Description	Temperature of Attack	Duration
C test	Fire alone test at the highest temperature for the longest time	950^oC ±40^oC	3 hours
W test	Fire and water test simulating a sprinkler system	650^oC ±40^oC	15 minutes fire plus 15 minutes sprinkler
Z test	Fire test with indirect mechanical shock	950^oC ±40^oC	15 minutes fire plus impact every 30 seconds

BS EN 50200 - Harmonised Fire Performance Standard

The harmonised standard covering test requirements for fire performance for these smaller cables is BS EN 50200.

The test to BS EN 50200 includes direct flame at a notional temperature of 842°C with mechanical shock to the back board on which the test cables are mounted. There is also a separate test for the cable included in Annex E which includes a water, fire and mechanical shock element.

BS EN 50200 Fire performance cable classifications

The cables are classified under the following classifications:

PH15 - 15 minutes duration

PH30 - 30 minutes duration

PH60 - 60 minutes duration

PH120 - 120 minutes duration

BS8491 - Fire performance standard for larger cables

The British Standard which caters for cables with a diameter greater than 20mm is BS8491.

The test method in BS8491:2008 involves subjecting the cable under test to radiation via direct impingement, corresponding to a constant temperature attack of 842^oC; to direct mechanical impacts corresponding to a force of approximately 10N; and to direct application of a water jet simulating a firefighting water jet.

The test method given in this standard includes three different test durations to allow testing of cables intended for different applications:

F30 - for 30 minutes duration

F60 - for 60 minutes duration

F120 - for 120 minutes duration.

IEC 60331 - International Fire Performance standard

An International standard for Fire Performance tests is IEC 60331 consists of the following parts under the general title: Tests for electric cables under fire conditions – Circuit integrity:

Part 1: Test method for fire with shock at a temperature of at least 830°C for cables of rated voltage up to and including 0.6/1kV and with an overall diameter exceeding 20mm.

Part 2: Test method for fire with shock at a temperature of at least 830°C for cables of rated voltage up to and including 0.6/1kV and with an overall diameter not exceeding 20mm.

Part 3: Test method for fire with shock at a temperature of at least 830°C for cables of rated voltage up to and including 0.6/1kV tested in a metal enclosure.

Part 11: Apparatus – Fire alone at a flame temperature of at least 750°C

Part 21: Procedures and requirements – Cables of rated voltage up to and including 0.6/1kV

Part 23: Procedures and requirements – Electric data cables

Part 25: Procedures and requirements – Optical fibre cables

NOTE Parts 21, 23 and 25 relate to fire-only conditions at a flame temperature of at least 750 °C.