Arc flashes and arc blasts are two components of a complex electrical phenomenon: the cause (arc flash) and effect (arc blast). When a short circuit (or arc flash) occurs, it can often cause an arc blast, a type of highly dangerous electrical explosion.
Arc flash is the burning energy of an arc that can cause equipment damage and injuries to those in close proximity to the arc. The arc blast is the explosive energy of an arc, like a very loud explosion of gasses and metal traveling at 700 miles an hour.
Hazards of an Arc Flash and Blast:
- Shrapnel: Arc Flash/Blasts spray droplets of molten metal at speeds that exceed 700 MPH that can easily penetrate standard Personal Protective Equipment (PPE).
- Sudden Air Expansion: Blast pressure waves have thrown workers across the room.
- Fatal Burns – Fatal burns can occur even when the worker is several feet away from the arc. Clothing can ignite from 10 feet away unless proper PPE is used.
- Hearing Loss – An Arc Blast can have a sound magnitude of 140 dB two feet from the arc and can cause permanent hearing loss.
- Damage to eyesight – Arc blasts can create high-intensity light flashes that are capable of causing both temporary and long-term vision problems when not wearing proper PPE.
The National Fire Protection Association (NFPA) published the 2021 Edition of the NFPA 70E Standard, which instructs employers to conduct an arc flash analysis to determine the amount of thermal energy that could be generated in an arc flash incident. The information is then used to define a flash protection boundary around the potential source, and to determine the level of flame-resistant apparel and other personal protection equipment required when employees cross the boundary.
CED’s experts who opine on these accidents have experience with arc flash and arc blast. This experience often comes from journal review, standard review and calculations, and physical inspection of evidence. To find out more about how and why arc flash occurs and causes fires and explosions, contact CED and see our full list of experts here.
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