6 KEY THINGS TO UNDERSTAND ARC FLASH
Oct 12, 2020
There are few things no utility worker wants to experience – ARC flash is one of them. The phenomenon is described as a sudden, bright, blinding light and heat that occurs because of a rapid release of energy between two bus bars. As much as 80% of all electrical injuries are burns resulting from an ARC flash caused by the ignition of flammable clothing. Let’s highlight six key facts to help understand more about ARC flash risks.
What Is An ARC Flash?
An ARC flash is caused by the ionization of air that can occur under certain conditions during a fault, or short circuit of high voltage equipment. The result is the formation of an electrical ARC of ionized gas that can discharge a violent pressure wave with extreme temperatures as high as 35,000°F.
The violent pressure wave that’s discharged can reach up to 2,000 lbs./square foot, causing serious risks including:
- Ear drum damage which starts at 720 lbs./sq. ft
- Lung damage which typically begins at 1,728 lbs./sq. ft
- Sound that exceed 140 dB
- Molten metal and shrapnel that exceed 700 mph
Air and materials exposed to ARC flash expands to be 67,000 times their normal size. A blast can occur when Copper vaporizes as it expands 1,670 times its normal size.
What Causes ARC Flash?
ARC flash can be initiated through accidental contact, equipment which is underrated for the available short circuit current, contamination or tracking over insulated surfaces, deterioration, or corrosion of equipment. In the United States, ARC flashes occur as often as five to 10 times per day.
How Do We Protect Workers?
ARC Rated (AR) Garments help provide flame and thermal break open protection from direct exposure to an electrical ARC flash. AR garments are designed and treated to help limit exposure and burn percentage as a result of the electrical ARC flash incident.
In order for a garment to comply with OSHA 1910.269 or NFPA 70E, it must go through two basic testing requirements of ASTM F1506: