Arc Flash
An arc flash is an uncontrolled electrical arc in power equipment that releases temperatures of several thousand degrees, a pressure wave and molten metal within milliseconds, posing a severe hazard to both personnel and the installation itself.
Cause and effect
An arc flash occurs when an insulation weakness, a foreign object or an operating error ignites an arc between conductors or to earth given sufficient available short-circuit power. The energy released produces temperatures that can exceed the surface of the sun, vaporises metal explosively and generates a pressure wave with shrapnel effect. Loss severity depends largely on the available short-circuit power at the fault location and the clearing time of the upstream protective devices.
Risk mitigation
Measures to limit the impact include a documented short-circuit and selectivity study, protection coordination designed for fast fault clearance, engineering controls such as arc-fault detection systems or segregated busbar enclosures, and organisational measures such as performing live work only after de-energisation and with suitable personal protective equipment. Calculating arc-flash energy using recognised methods provides the basis for defining hazard boundaries and protective measures.
Insurance relevance
Beyond personal injury, arc flash events regularly cause severe property damage to switchgear and long replacement lead times for specialised components. For property and machinery insurers, it is therefore relevant whether an up-to-date short-circuit study exists, whether protective devices are designed for fast tripping, and whether maintenance work is consistently performed in a de-energised state.