In our previous Keystone Academy blog ‘What is the Difference Between FRT and FR Cable?’, we shared that Fire Resistant (FR) cables are a fire safety product, which means they not only reduce the spread of fire, but will also maintain circuit integrity in the presence of fire.
Resistance to Fire: IEC 60331-21
IEC 60331-21 is the basic international testing standard for fire resistant cables. There is one set of requirements to test for cable’s circuit integrity under fire:
• Resistance to fire alone (Temperature of at least 750°C for 90 mins)
This test standard is suitable for low voltage power cables and control cables with a rated voltage up to and including 0.6/1kV. During the test, the cable is connected to a transformer output with a 2A fuse in each phase. The test is deemed successful if there are no fuse fails and the test light is not extinguished.
Resistance to Fire: SS 299
Singapore Standard SS 299 specifies tests for fire resistant cables. This standard was updated in September 2021, and it is a modified adoption of British Standard BS 6387:2013, 'Test method for resistance to fire of cables required to maintain circuit integrity under fire conditions'.
FR cables must pass protocols C, W, and Z test parameters to be considered fully compliant.
For information on the old standard, SS 299-1:1998, refer to the blog "SS299:2021 Updates - Fire Resistant Test Standard".
Resistance to Fire: BS 6387
British Standards BS 6387 is the most commonly recognised FR cable test standard.
Based on the latest standards update BS6387:2013, an FR cable is considered compliant only if it passes the BS 6387 Cat. CWZ requirement:
• Resistance to fire alone, Category C (950 °C ±40 °C for 3 hours)
• Resistance to fire with water, Category W (650 °C ±40 °C 15 mins flame, 15 mins water)
• Resistance to fire with mechanical shock, Category Z (950 °C ±40 °C 15 mins flame, mechanical shock every 30s)
Keystone Cable’s fire resistant range complies with all of the above international standards.