An arc flash is an explosive release of energy caused by an electrical fault between conductors or between a conductor and earth. Temperatures can exceed 20,000°C, causing severe burns, blast injuries, and permanent blindness in a fraction of a second. Arc flash incidents most commonly occur during switching, racking, or testing of high-energy electrical systems. This talk explains the risk and the protection required.
Key Hazards
Third-degree burns from arc flash temperatures exceeding 20,000°C
Blast pressure injuries throwing workers across the room from the explosion
Permanent blindness from intense UV radiation produced by the arc
Molten metal and shrapnel projected at high velocity from the fault point
Control Measures
Carry out an arc flash risk assessment for all switching and racking operations on high-energy systems.
Wear arc-rated PPE including face shield, arc flash suit, and insulated gloves for the calculated risk level.
De-energise and isolate electrical systems before any work wherever reasonably practicable.
Use remote switching and racking devices to increase the distance between the operator and the arc source.
Ensure only authorised and competent persons carry out switching operations on high-energy equipment.
Stand to the side of switchgear doors during opening and closing to reduce blast exposure.
Verify that protective relays and fault current protection devices are functional before switching.
Label switchgear with the arc flash hazard level and the required PPE at each operating point.
Brief all electrical operatives on the arc flash risk assessment findings before any switching activity.
Remember
An arc flash risk assessment is required before switching or racking on high-energy systems
Wear arc-rated PPE matched to the calculated incident energy level for the specific equipment
De-energise and isolate electrical systems before work wherever reasonably practicable
Use remote switching devices to increase the distance between operator and arc source
Stand to the side of switchgear doors during operation to reduce blast pressure exposure
Label switchgear with the arc flash hazard level and required PPE at every operating point
Applicable Legislation: Electricity at Work Regulations 1989 · IEEE 1584 (Arc Flash Hazard Calculations) · Health and Safety at Work etc. Act 1974 · Personal Protective Equipment at Work Regulations 1992