Arc Flash Hazard

Another hazard electricity may present is an arc flash.

Arc flash occurs when several electrical conductors are placed close to each other, with significant fault currents flowing through them. In this situation, ionization of the air can take place as a result of various factors, such as differences in potential, which leads to a low resistance path and allows current to flow through the air gap between conductors.

Many people assume that low voltage equipment is safe from arc flash, but arc flash hazard levels may be higher at low voltages due to the high fault currents. Most incidents that occur in low voltage systems are caused by human error, such as a tool slipping while a technician works on electrical equipment.

Arc flash can also be caused by the following:

• Carelessness or accidents, such as touching the wrong surface with a test probe
• Improper tools, installation, and work techniques
• Lack of electrical safety awareness and training
• Use of damaged electrical materials/equipment
• Obstruction in disconnect panels
• Insulation damage, gaps, or wear and tear
• Dust, debris, and corrosion on electrical conductors
• Improper preventative maintenance for circuit breakers and switches
• Exposed live parts, loose connections, or corrosion
• Static electricity or high voltage cables
• Exposure of electrical equipment to water or other liquids

An arc flash is an explosive electric shock that can include a bright flash, an explosive expansion of molten metal, a loud blast, thermal radiation, and an intense flow of electric current.

Injuries resulting from the explosive concussion of an arc flash can be the direct result of the force of the blast. The pressures involved are huge and sufficient to collapse the lungs of those in close proximity. Nearby workers can be thrown by the blast, which can cause blunt-force injuries. Physical objects are often dislodged and become dangerous shrapnel.

Permanent hearing loss can result from the volume of the blast. Mental disorientation can also result, which itself can lead to other hazardous conditions.

The extreme heat of an arc flash can also cause severe burns. No contact with the electrical circuit is required for this to occur, as the arc can energize air particles to complete the circuit. The intensity of the arc flash can cause severe burns almost instantly.

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