An arc fault is a dangerous electrical explosion that generates extreme heat, force, energy, and brightness. It is among the most serious hazards faced by industrial electrical companies.
Arc faults frequently result in an arc flash, a fierce burst of heat energy and bright light. The flash is distinct from the arc blast, the supersonic shockwave that results from the arc fault’s uncontrolled energy as it vaporizes its metal conductors.
Unpredictable, costly, and extremely dangerous, arc flashes can completely disrupt a company’s operations. Nevertheless, they are a common occurrence in electrical operations across the country. In fact, five to ten arc explosions occur in the United States every day. These intense explosions are potentially lethal and can cause millions of dollars in damage.
Arc flashes are caused by low impedance connections from the air to the ground, or to an appropriate voltage phase in an electrical system. In effect, this creates a short circuit through the air, resulting in an enormous concentration of energy with:
- Extreme heat that can spike up to 35,000 °F
- Explosions of molten metal and plasma
- Vaporizing conditions
- Destruction of equipment, including melting or evaporation of the host system
- Fire, electrical burns, and vision-altering brightness
- Permanent nerve damage and injury to employees and bystanders
Arc Flash Protection Products
For safety purposes, arc faults are generally divided into arc flashes and arc blasts. Each of these large-scale hazards is subject to distinct rules and regulations, and each can be mitigated with specialized personal protective equipment (PPE).
For example, high-performance protective clothing designed to withstand arc flashes must meet verified arc thermal performance values (ATPV) listed in the National Fire Protection Association (NFPA)’s 70E Standard. These work shirts, bibs, overalls, jackets, and hoods are further supplemented with:
- Specialized tools with insulation and safety grips
- Caps and full-brim helmets outfitted with premium face shields
- Goggles and safety glasses
- Gear testing and inspection equipment
- Insulated rescue tools for emergency use
- High-voltage gloves and guards
Splashes, loose objects and projectiles, vapors, extreme heat, and chemical penetration are all concerns for workers in the case of an electrical incident. To prepare workers for these risks and properly protect them from them, the Occupational Safety and Health Administration (OSHA) introduced OSHA/NFPA 70E, a definitive work safety standard for the entire electrical industry. These guidelines help companies minimize the risks posed by their workplaces, operating procedures, and supporting equipment, providing effective protection against any scenario in which an arc flash could occur.
PPE: The Last Line of Protection
Appropriate equipment maintenance, vigilant training, accurate labeling, and thorough safety protocol are all essential precautions that can prevent arc flashes and similarly dangerous incidents. However, an arc flash can be sparked by something as small — and unpredictable — as a rogue mouse in a break area.
Because of the severity and unpredictability of arc faults, personal protective equipment (PPE) in an electrical facility is more a necessity than an option. The last line of protection between a worker and danger, OSHA ranks PPE in four major categories:
- Category 1, Arc-Rating of 4 cal/sq cm, includes arc-rated face shields, safety goggles, hearing and head protection, leather gloves, arc-rated clothing, and leather footwear
- Category 2, Arc-Rating of 4 cal/sq cm, adds an arc-rated balaclava or hood and jacket to the Category 1 requirements
- Category 3, Arc-Rating of 25 cal/sq cm, adds an additional layer with an arc-rated flash suit consisting of a high-performance hood, jacket, and pants on top of Categories 1 and 2
- Category 4, Arc-Rating of 40 cal/sq cm, introduces the highest level of protection with a head-to-toe arc-rated flash suit, full head and face protection, arc-rated gloves, and more
With the safety of their workers possibly at stake, it’s imperative that electrical companies invest in effective safety measures that protect their most valuable assets from the perils of arc flashes. To learn more about arc flash preparation, reach out to a safety professional today.
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