Shock & Arc Flash Hazards

The Shock and Arc-Flash Hazard

Air surrounding the arc is instantly heated and conductors are vaporized causing a pressure wave termed “Arc Blast”

Direct contact is not required, the burns come from a PLASMA FIRE and explosion called an “ARC-FLASH”. In this case a plasma fire is caused by electrical current inducing enough heat to cause the metal; copper and aluminum, to vaporize, then ignite. Temperatures at the arc terminals can reach or exceed 35,000 degrees Fahrenheit (F) or four times the temperature of the sun’s surface! All known metals vaporize at this temperature!

As the arc begins, metal begins to heat rapidly and melt. First, the molten metal boils throwing off liquid globules, still continuing to heat. At this point one of two things happen. The cycle may run out of fuel and extinguish itself or, if it continues past 300 milliseconds, any copper present will transition to vapor, thus becoming an unquenchable plasma fire.

As conductors vaporize they may project molten particles similar to buckshot. Three inches of vaporized #10 copper wire expands to approximately one cubic foot or 67,000 times its solid state.

• One cubic inch (1″x1″x1″) of copper will expand almost instantaneously into a 7ft x 7ft x 7ft cube of 30,000 degrees F gas.