What does a two hour fire rating mean?
The fire test for determining the fire rating of a cable consists of exposing a cable and fittings to extreme temperature in a furnace over a period of two hours.
The temperature builds throughout the period to a final temperature of around 1030°C. The cables are subjected to their round operating voltage and a current flows through the conductors.
If the insulation fails, ie shorts to ground, or if the current stops flowing, the test has failed.
This test permits comparisons between different manufacturer’s products and provides a benchmark on which installation standards can be based.