Fire Resistant Cable Testing Standard
IEC 60331 VS BS6387
The most important feature during fire condition is that the fire alarm circuit is working under the fire, in case the cables connecting the fire alarm circuits are burnt the whole alarm system is useless.
So there was a great need for a type of cables which operate under the fire conditions, fire resistant cables provide a good system for emergency circuits where the integrity of the electric network is maintained during the fire conditions.
The cables are tested based on the following standards:
IEC 60331 Fire Resistance Test
A sample is connected to an electrical supply at its rated voltage. Fire is applied for a period of 1 .5 hours. The temperature on the cable is 750° C, The test shall continue for the flame application time , after which the flame shall be extinguished but the cable sample shall remain energized for a further 15 min.
The cable must maintain its circuit integrity.
BS6387 Fire Resistance Test
The test method given in this British Standard consists of three component Protocols, designated C, W and Z.
When separate test pieces from the same sample of cable are tested to each of these three protocols, these together comprise the full test. When the requirements of each one of the protocols are met, the cable may be designated as "category CWZ”.
BS6387 covers fire resistant cables with a voltage rating of 300/500V and 450/750V.
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BS6387 CABLE CATEGORIES |
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Resistance to fire alone |
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Category A |
650°C for 3 hours |
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Category B |
750° C for 3 hours |
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Category C |
950° C for 3 hours |
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Category S |
950° C for 20 minutes (short duration) |
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Resistance to fire with water (W) |
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Category X |
650° C for 3 hours |
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Category Y |
750° C for 3 hours |
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Category Z |
950° C for 3 hours |
