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The UK British Standard BS8519:2010 clearly identifies underground public areas such as car parks as "Areas of Special Risk". Where cables are required to be flame retardant to Australian Standard test methods AS/NZS60332-3 it is concerning these tests are not conducted on cable samples preconditioned to the operating temperature, rather commencing at room temperature. Highly flame retardant cables with a high oxygen index may help here because they may limit the fire spread. Shielded Cables: These are used in applications involving high voltage transmission like in security systems installed in public spaces. Evacuation of these public environments with children, aged and disabled people, can be very slow during emergencies, and it is our responsibility to ensure everyone is given the very best chance of safe egress during fire emergencies. In these environments, more stringent test protocols for fire resistance including for electric cable systems may need to be specified by designers.. In particular, fires in confined areas like buildings, tunnels and underground environments cause oxygen levels to drop near the fire source and this can contribute to incomplete burning and smoldering which may produce increased amounts of smoke and toxic by-products including CO (Carbon Monoxide).

Smoke will contain particulates of carbon, ash and other solids, liquids and gasses, many are toxic and combustible. Typically the larger the fire the more smoke is generated so anything we can do to reduce the spread of fire will also correspondingly reduce the amount of smoke. Enclosing cables in steel conduit will reduce flame propagation at the point of fire but hydrocarbon based combustion gasses and smoke from the decomposing polymers will propagate along the inside of conduits to switchboards, distribution boards and junction boxes in other parts of the building where any spark such as the opening or closing of circuit breakers, or contactors is likely to ignite the combustible gasses leading to ignition or even explosion and spreading of the fire and smoke to other locations. However, any wiring system (cable or bus duct) required to operate in fire must not only account for the electrical integrity of the circuit in order to ensure the reliable function of the life safety and firefighting equipment connected but also for the effects of fire on voltage drop, reduced conductor conductivity due to increased conductor resistance at fire temperatures and the additional ohmic heating generated by carrying the required load under these conditions.

Fire experts tell us most fire related deaths in buildings are caused by smoke inhalation, temperature rise and oxygen depletion or by trauma caused by jumping in trying to escape these effects. Simply specifying low smoke cables to common British or IEC standards then thinking this will provide a low smoke environment during a real fire may unfortunately, in practice, be of little help for the people actually involved. With the release of AS/NZS3013:2005, Australia has perhaps a better certification regime than Europe or UK for fire rated wiring systems (The American UL2196 is perhaps the world’s best fire resistance protocol for wiring systems as it requires fire and water testing in both horizontal and vertical configurations). Research by Universities, Institutions, and Authorities in Australia and around the world have identified that for modern above ground cellulosic buildings, the use of light weight thermoplastic building materials, synthetic foams, and fabrics, along with synthetic materials and plastic contents have significantly increased dire loads resulting in time temperature fire profiles well above the original parameters of the existing, early 1900’s test protocol ISO834-1 (AS/NZS1530pt4) as mandated by the Australian NCC.

This effect is known and published by Olex Cables Australia at the 8th International Conference on Insulated Power Cables in Versailles, France. The electrical cables used to power the lights and appliances in your home come in several different cable sizes, primarily to accommodate the amount of current required to run the items that are drawing power from it.All cables are rated to carry a specific amperage meaning that the load imposed on them should be no more than they are able to safely carry. A wire is designed with a single electrical conductor whereas an electrical cable is designed with several wires in a common sheathing but both of them are used to carry electrical current. The cable size calculator can be used to manually calculate the minimum gauge of wire that can safely carry the load using the conditions you specified, for example, using the calculator found at Omnicalculator and in the Ampacity Charts and Calculators website of Cerrowire. To calculate the diameter of the wire when knowing only the area, what is electric cable the equation has to be done backwards.The area is divided by 3.142 (Π) and the square root (√) of the answer is the radius (r). Steel wire or strands are added for tensile strength, and the entire cable is then wrapped in a polyethylene sheath, or jacket, for stability.