Fire Resistant Test Standards – Explained!

Written by Keystone Academy | Apr 7, 2021

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.

This is critical so that life-saving electrical installations, such as fire alarms, smoke detectors, PA systems, and emergency lighting, can perform their functions in the event of a fire.

In addition to complying with LSZH flame retardant (FRT) tests (IEC 60332, IEC 60754, and IEC 61034), LSZH FR cables are also tested to IEC 60331-21, BS 6387 or SS 299 to ensure that the fire-resistant cables maintain circuit integrity under fire conditions. In this article, we introduce the differences among the 3 common LSZH FR test standards.

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 and control cables with a rated voltage of up to 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 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.

View full post