Protecting your workers and your companies interests from arc flashes

Arc flashes are one of the most dangerous phenomenons in industry today. In the USA around 8% of fatalities are due to electrical shocks, fires and explosions. In the chemical industry, 55% of fatalities in a 5 year period were attributed to burns and explosions connected with electrical ignition sources.
Arc flashes are so dangerous because of the huge amount of energy that can be released in such a short space of time. Lasting normally only a few milliseconds, temperatures at the arc can reach tens of thousands of degrees. This temperature causes metals to vaporize. Going from a solid to gaseous phase with a temperature increase such as this causes very rapid expansion, copper expanding to up to 67,000 times its normal solid volume. The metal vapour in the air caused by this is also highly conductive, which helps to propagate the arc flash. Aside from the sever conditions that exist close to the incident. The blast wave and high temperature also cause a large amount of metal plasma, molten metal, high energy radiation and other debris, which can be dangerous to people at much larger distances from the incident itself.
Each arc flash can cause huge damage to a company in terms of downtime, repairs, medical expenses and insurance costs. With survivors of arc flashes often needing years of skin grafts and treatments and possibly not ever fully recovering. Alongside the obvious ethical commitment of companies to keep their workers safe in the workplace, means that arc flash safety is something that cannot afford to be ignored.
Knowledge is the best defence against arc flashes and a full analysis of any electrical systems, especially those dealing with high voltages is the first step. An all too large number of arc flash victims had no idea about the dangers involved in their line of work. A good way to ensure people have working knowledge of arc flashes is to make it required for people to have work permits such as the NFPA 70E, or a qualified guide for other visitors.
The first step in mitigating the problem of arc flashes is to determine where in your system arc flashes are likely to occur, you need to calculate the maximum fault currents which may happen during a short circuit and where they are likely to arc. When this is known, safety equipment can be implemented, in the form of fuses, grounding resistors, arc eliminators and other such fault current controlling devices.
With these in place safety distances can be found for electrical systems and governing levels of PPC can be determined for those distances. It is important to note, that nobody should enter danger zones without PPC, even when they won't be touching any of the electrical systems, and that even when equipment is powered down, PPC must be worn until it is confirmed that the system is totally powered down.
Many companies stop after doing an analysis of their systems and don't implement proper safety guidelines or mitigation procedures. This is simply a waste of time and money and something this serious can't afford to be ignored. This can save money for your company and more importantly, lives!

The author is experienced in
Arc Flash Protection,
Arc Flash PPE and
Arc Flash Clothing