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Arc flash information

Arc Flash (also referred to as Arc Blast) relates to the outcome of a low impedance connection to ground or different potential in an electrical system. Low voltage arc flash consequences can be greater than high voltage, depending on the fault current levels and protection clearance times. Obviously if the electrical conductors or equipment is de-energised and no live work is undertaken, the arc flash hazard and risk is eliminated.

It has been stated in the United States, arc flash

  • burns account for approximately 80% of all electrical injuries
  • incidents result in, 1 death and 6 hospital admissions per day
  • ignition of flammable clothing adds to the burn severity.

Arc flash effects (but not limited to)

  • are only associated with working on or near live exposed electrical conductors/equipment and/or when operating energised electrical equipment
  • produce temperatures in excess of 15,000 degrees Celsius
  • produce plasma clouds, molten metal, pressure ways, sound waves, intense light, shrapnel, copper vapour, etc.

AS/NZS4863 - Safe Working on Low Voltage Electrical Installation, states

'Electrical workers working on or near exposed energised conductors shall wear flame retardant clothing covering the full body.' It is acknowledged that 100% cotton drill is not a flame retardant material. On or near means, where there is a possibility of coming within 500mm of exposed live low voltage conductors.

Arc flash safety is primarily concerned with eliminating the hazards, to prevent arc flash burns and injuries, should something go wrong when operating, or working on or near energised electrical equipment or exposed conductors.

Currently there is no Australian Standard that covers arc flash and industry generally utilise the American standards

  • Institute of Electrical and Electronics Engineers - IEEE 1584 Guide to performing arc-flash hazard calculations
  • National Fire Protection Association NFPA 70-E Standard for electrical safety requirements for employee workplaces.

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