Undoubtedly, cable durability is of great importance in many situations. Especially in cases involving fire, cable durability is of vital significance. Both the gases released by burning cables and their strength under flames must meet certain standards through various applied tests. Now, let us take a closer look at what these tests are. Since cables are used in buildings, hospitals, cinemas, theaters, schools, shopping centers, airports, factories, tunnels, etc.—places central to daily life—they must have properties such as non-flame propagation, non-spreading, non-breaking, low smoke density, and absence of toxic and corrosive gases. These properties can only be confirmed through tests performed on them.

In this content, we will examine the fire resistance tests carried out in 2M Cable laboratories:

• Horizontal Flame: IEC 60331-21
• Vertical Flame on a Single Cable: IEC 60332-1
• Electrical Continuity Under Water: BS 6387 Cat W
• Smoke Density: IEC 61034-2
• Vertical Flame on Cable Bundles: IEC 60332-3
• Mechanical Impact Under Flame: BS 6387 Z
• Electrical Continuity Under Flame, Impact, and Water: EN 50200 ANNEX E

Horizontal Flame Test – IEC 60331-21

This test measures the cable’s resistance to flame applied horizontally. A 1200 mm sample is exposed to flame at (750 ± 40) °C. If the cable remains conductive for 180 minutes under these conditions, it passes the test. The same setup is also used for vertical flame testing, where the flame temperature is (950 ± 40) °C and the duration is 180 minutes.

Vertical Flame on a Single Cable – IEC 60332-1

The resistance of a single cable against flame is tested. During the test, the flame’s progression is observed, and the flame propagation characteristics of the cable are measured. The sample is exposed to flame at a 45° angle for 60 seconds. The blackened portion of the cable is measured and compared with the values specified in the standards.

Electrical Continuity Under Water – BS 6387 Cat W

This test simulates the cable’s exposure to water during a fire. It determines whether the cable can continue conducting electricity under such conditions. The test temperature is (650 ± 40) °C, and the duration is 30 minutes. In the first 15 minutes, the sample is exposed only to flame; in the second 15 minutes, it is exposed to both flame and water. If the cable remains conductive for 30 minutes, it passes the test.

Smoke Density – IEC 61034-2 This test determines the extent to which gases released during cable combustion obstruct human visibility. Smoke is released into a room of standard dimensions. The sample burns for 40 minutes. Sensors on both sides measure light transmittance, which is then compared with the values specified in the standards.

Vertical Flame on Cable Bundles – IEC 60332-3

This test measures the effect of cables on each other during a fire. It is conducted in four categories: A, B, C, and D. For categories A and B, flame is applied for 40 minutes; for categories C and D, flame is applied for 20 minutes. If the damaged portion does not exceed 2.5 m, the product passes the test.

Mechanical Impact Under Flame – BS 6387 Z

This test measures the fire resistance of cables used in bent areas. A 1200 mm cable is mounted vertically in a Z shape. The test temperature is (950 ± 40) °C. For 15 minutes, a 25 kg weight is dropped at a 60° angle every 30 seconds. Electrical continuity is measured during these impacts.

Electrical Continuity Under Flame, Impact, and Water – EN 50200 ANNEX E

 This test determines the cable’s resistance to flame, impact, and water during a fire. The cable is exposed to flame at (830 °C ± 40 °C) in four stages (30, 60, 90, or 120 minutes). Every 5 minutes, a 25 kg weight is dropped at a 60° angle. If the test is conducted with water, then for half of the total duration the cable is exposed to flame and impact, and for the other half it is additionally exposed to water. If the cable continues conducting electricity throughout the test, it passes.