Hi and welcome back to my blog, I recently read a very interesting article regarding the fire performance of electric cables.

Interestingly, electrical cables are frequently blamed by the media and fire authorities as the cause of building fires however, it is often not the failure of the cable which starts a fire but the misuse of the cable by frayed or damaged insulation, overloading due to incorrect or insufficient circuit protection, short circuit or over voltage. These type of situations cause high temperatures in the cable conductors or, in some cases, electrical arcing, which can heat the cable insulation and surrounding combustible materials to start a fire.

Cable manufacturers do endeavour to manufacture electric cables which under the above situations, or in cases where a fire is started by another unrelated cause, will not burn or at least will not help spread a fire through the building.

There are various cable flame retardant test standards written by technical standards committees in both Europe and USA. These common standards propose test methods intended to determine if the electric cables or materials they are made from are self-extinguishing (Flame Retardant). Authorities may also embed these test methods into mandatory building design codes.  I will be following this further to determine if Australia is in fact using the same or similar testing and incorporating into Australian Building Design Codes.

PVC, XLPE, EPR, CSP, LSOH (Low Smoke Zero Halogen) and even HFFR (Halogen Free Flame Retardant) cable materials are based on hydrocarbon polymers, which are not flame retardant and have a high fire load. Cable manufacturers make them flame retardant by adding compounds and chemicals. Ok, so this restricts the volatility of burning but the fuel content of the base polymers still remains.

Inside all buildings electric cables provide the connectivity, which keeps lights on, air-conditioning working and the lifts running. It powers computers, office equipment and provides the connection for our telephone and computers. Even our mobile phones need to connect with wireless or GSM antennas, which are connected to the telecom network by fibre optic or copper cables. Cables ensure our safety by connecting fire alarms, emergency voice communication, CCTV, smoke shutters, air pressurization fans, emergency lighting, fire sprinkler pumps, smoke and heat detectors, and so many other features of a modern Building Management System.

Where public safety is important we often request cables to have added safety features such as flame retardant to ensure the cables do not easily spread fire, circuit integrity during fire so that essential fire-fighting and life safety equipment keep working. Logically and intuitively we think that by requesting these special properties the cables we buy and install will be safer but because cables are installed by many different trades for different applications and are mostly hidden or embedded in our constructions, what is often not realised is that the many miles of cables and tons of plastic polymers which make up the cables can represent one of the biggest fire loads in a building.

……….. ‘Til the next time Greg