WHAT'S AN ARC FLASH?

An electric arc is a brief, but lethal hazard which expels large amounts of deadly energy. In jargon, such incident causes an ionization of the air that will cause serious harm to equipment and people. Damage is caused by both the explosion and the heat radiating from the blast of vaporized materials.

Within fractions of a second, the explosion of an electric arc may reach temperatures exceeding 19,000 degrees Celsius. This is roughly 4 times hotter than the surface of the sun. This heat can cause serious, even fatal burns, as well as ignite clothing and other nearby material and objects. Such high temperatures vaporize all materials like water (present in the air as humidity) and liquefies metal parts in the vicinity of the incident, such as copper and aluminum. This in turn means a massive volume expansion that results in explosive pressures and sound waves which form one of the biggest dangers of an arc flash incident. 

A simplified enumeration of the nature of an electric arc:

• The duration of an electric arc is relatively short, often not longer than 0,5 second.
• The temperature that is unleashed is approximately 19.000°C – which is as much as 4 times warmer than the surface of the sun.
• The noise level of an electric arc could go up to 165dB – as an exemplification: a fighter jet that passes you at close range produces about 170dB.
• One of the biggest dangers of electric arc is the volume expansion of materials as a result of the high temperature. The extreme heat vaporizes all materials like water and copper. Water increases volume with a factor 1670. Copper expands in its vaporized circumstance 67.000 times its original volume.
• The shockwave as a result of the arc flash can be higher than 2000 lbs/sq. ft., which is 4 times more powerful than Mike Tyson could hit in his best days.

It goes without saying, that proper PPE can make the difference between life and death, or at least contribute significantly in the reduction of burn wounds. In the core, the protection from electric arc is not so much different from the protection against the burn injuries that are caused by a flash fire. In both cases it is the aim to protect wearers against thermal hazards that could result in 2nd degree burn wounds or worse. It is the nature of the hazard that makes flash fire protection different from electric arc protection.