Vertical Flame Testing 2018-05-23T03:22:30+00:00


The Vertical Flame Test to BSEN 60331-1-2 is designed to assess the flame retardant properties on a single cable length.

Test methodology requires a cable sample of approximately 600mm to be placed vertically between two clamps. A burner flame is then applied for the duration specified in Table 1 below, igniting the cable. After the designated length of time, the flame is removed and the cable should self-extinguish. In order to pass this cable fire performance test, the cable burn should not reach 50mm from either clamp.

Vertical Flame Test BSEN 60331-1-2: Table 1

Overall Diameter of test piece (mm)          Time for flame application (s)
D ≤ 25                                                               60 ± 2
25 < D ≤ 50                                                     120 ± 2
50 < D ≤ 75                                                     240 ± 2 D > 75                                                               480 ± 2

This fire performance test is performed on a finished cable or the insulated single conductors, meaning all layers of the cable construction are subjected to the burner flame.


The Canadian Standards Agency (CSA) also has a single wire Vertical Flame Test designated CSA FT1, which is performed on the finished cable or equipment wire. The CSA FT1 cable standard and the cables are designed primarily for the North American and export markets.


UL VW-1 is the American standard for cables and wires, also known as UL 1581, and determines flame retardancy. It requires 5 cycles of 15 seconds of a burner application with a break of between 15 seconds and 60 seconds between each cycle depending on the requirements of the individual cable standard.

Passing the VW-1 test requires the wire to self-extinguish within 1 minute and for the paper flag affixed to the top of the sample to not be more than 25% carbonised, and for the droplets released during burning to not ignite the cotton underneath.

For more information on our cable fire performance test capabilities, please contact our technical team who can advise on the most appropriate cable test for your application. The classifications for fire performance testing against British, European and international standards is answered in our FAQs.

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