What is ARC Flash?

An arc flash (also known as arc blast) is a sudden, explosive electrical arc that results from a short circuit through air. The air in the vicinity of an arc flash is heated to between 5,000 and 35,000 degrees in no more than 1/1000 of a second, becoming an electrically-conductive plasma. The sudden heating can cause a shock wave blast equivalent to several sticks of dynamite and carrying vaporized metal and shrapnel.

What Causes Arc Flash?

An arc flash occurs when a conducting object approaches an exposed, high-amp electrical source. High voltage is not required for an arc flash. Most incidents occur on 120 to 240V equipment, and arc flashes can occur at voltages as low as 50V. Arc flash is a danger whenever energized equipment is being worked on, but there are certain conditions that make arc flash more likely. These conditions include:

• Dropped tools or other sources of sparks near energized equipment
• Gaps in insulating materials which expose conducting surfaces
• Corroded or improperly installed or maintained equipment

Arc flash most often occurs when performing the following tasks:

• Removing panels and opening electrical equipment doors
• Racking breakers
• Opening and closing breakers
• Taking voltage measurements

Learn more. Watch this informative Arc Flash Demonstration Video.