Arc flash vs arc blast

12-03-2019 | Safety

When an arc fault occurs, there’s a massive electrical explosion. Both arc flash and arc blast are separate byproducts of that electrical explosion. The arc flash is the light and heat from the explosion, while the arc blast is a pressure wave that follows.

It’s estimated that between five and ten arc fault incidents occur every day in the United States, based on findings from the Bureau of Labor Statistics. The goal of anyone working with electricity is to go home safely at the end of the job. Step one is to understand the dangers you’re working with.


What is arc flash?

Arc flash is the light and heat created from an arc fault explosion. Temperatures of an arc flash can reach as much as 2,800 to 19,000 °C (5,000 to 35,000 °F). To give you some perspective; the temperature of the surface of the sun is estimated at 5,500 °C (9,932 °F). Temperatures that high can ignite the clothing and burn the skin of anyone within a few feet. The arc flash can also melt metal, cause lung and eyesight damage and even lead to hospitalization or death.

What is arc blast?

The arc blast is the pressure wave created after an arc fault. These can be strong enough to throw a fully grown technician to the ground or cause additional equipment damage. Arc blasts can cause damage to your hearing or brain functions. The blast can also cause loose equipment, tools, machinery and debris to go flying which can cause further damage or injury.

What causes arc faults?

One of the major causes of arc flash is voltage transients (spikes), resulting from switching reactive loads or lightning strikes. The transient might last only microseconds, but it can carry thousands of amps of energy. If this happens while measurements are being taken, a plasma arc can form; either inside the measurement tool or outside.

Other causes of arc faults include situations as simple as:

  • Touching a test probe to the wrong surface
  • Worn or loose connections
  • Gaps in insulation
  • Improperly installed parts
  • Dust
  • Corrosion

Preventing injuries

Both arc flash and arc blast can cause injuries and be potentially fatal. Taking the proper precautions to prevent an arc fault and stay safe if one does occur is important. Read Arc fault boundary and safety to learn what steps to take in order to stay safe.

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