Our PH30 & PH120 cables are known as enhanced fire resistant which simply means it has been developed specifically with certain scenarios in mind. Some buildings would require a longer fire alarm system activation and these cables are ideal for those fire alarm installations. For example, larger buildings may involve a multi-phase evacuation process so the fire alarm would need to operate for a much longer time.
The cables are tested by being placed in a direct flame and timed until the circuit breaks. From this experiment, they can work out the length of time that cable can survive in direct heat situations, typically around 830°C. The failure point is said to be when the cable does not maintain the voltage or breaks. The cables are then assigned a figure based on the number of minutes it survived, with 120 being the most.