Electric arc hazards and protection

Electrical arcing poses extreme danger to workers. An arc incident presents a number of different hazards, requiring specialist equipment in order to keep operatives safe.

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Electric arcing occurs when electrical current jumps between two conductors. This can happen for many reasons including equipment failure, accidental contact with live parts, or carrying out live work on damaged equipment.

When an arc fault occurs, electrical current is discharged through the air resulting in multiple dangers. A huge explosion of heat, light, sound and shrapnel puts anyone working nearby at risk of serious injury.

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Fire & heat

An arc incident can ignite a high-intensity, fast-spreading fire and heat generated in the explosion can reach 20,000°C. PPE needs to stand up to heat and prevent flame spread as much as possible.

The EN 61482 standards specify thermal hazard test methods for electric arc protective clothing. The box test method allows garments to be classified as either Class 1 (tested at 4kA) or Class 2 (tested at 7kA), whereas the open arc test method determines arc rating. Three arc ratings are applicable to protective clothing: ELIM (Incident Energy Limit), ATPV (Arc Thermal Performance Value), and EBT (Breakopen Threshold Energy).

Protective clothing that meets the ISO 11612 standard is tested for flame spread, heat performance and molten metal splash. The standard includes optional requirements for protection against the thermal effects of an electric arc event and prediction of injury by burns.

GS-ET-29 sets out testing requirements applicable to faceshields for electrical works, including thermal protection and additional light transmittance requirements. Faceshields tested to American standard ASTM F2178 are assigned an Arc Thermal Performance Value (ATPV) expressed in cal/cm2.

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Impact hazards

The explosion resulting from an arc incident, called an arc blast, ejects particles at high speed. Sharp pieces of broken equipment and molten metal can cause injury to the eyes and skin.

In addition to thermal testing, electric arc faceshields are also tested for impact resistance, protecting wearers against projected debris.

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Noise

Impulse noise resulting from the arc blast can exceed 140dB. Personal hearing protection may not be able to attenuate noise to a safe level but provides some protection by reducing sound pressure as far as possible.

Ear defenders can be unsuitable if they contain conductive materials and ear plugs are often selected for use where there is a risk of electric arcing.

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Light radiation

The arc flash emits intense ultraviolet and visible light radiation, with the potential to cause blindness and other vision problems.

The GS-ET-29 standard includes requirements for visible light transmittance. Faceshields are tested and assigned a class based on performance. Electric arc faceshields are also tested for UV filtering, ensuring the visor can protect against harmful ultraviolet light.

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Arc incidents present extreme danger with devastating consequences for workers. A risk assessment is required to identify hazards and appropriate control measures to keep people safe. The focus should be on mitigation – avoiding live work wherever possible, inspecting and maintaining equipment and tools, and providing regular training for operatives. PPE needs to protect against multiple different hazards to reduce the risk and severity of injury in the event of an incident.

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Find out more about PPE for electrical hazards.

Learn more about safety helmets offering electrical protection.