ARC FLASH SAFETY

In predicting the severity of the thermal effect of an arc flash, it is recommended that the IEEE 1584 Guide for Performing Arc Flash Hazard Calculations 2002 is used, which is an auditable standard and widely accepted in the electrical engineering community. The calculations take into account distance to worker, conductor gap, voltage, prospective fault current and disconnection time.

Where the arc flash hazard cannot be eliminated then suitable risk controls should be in place (preventative or protective measures). The need for risk assessment is embodied in the Management of Health and Safety at Work Regulations 1999 (MH&SAW Regs) Risk control measures should look at preventing the incident rather than mitigating against it. The first line of defence therefore must be prevention.

Where the risk cannot be controlled by prevention or where there is a residual risk of injury then it may be necessary to consider mitigation to prevent injury to the worker. The requirement for and suitability of mitigation techniques must form an essential element of any risk assessment. Where protection against the thermal effects becomes necessary it must be emphasised that PPE does not prevent the accident happening in the first place.

Risk Assessments must be recorded and may also require that field marking of equipment. Safe systems of work, safety rules and procedures should be implemented and trained. Risk Assessments need to document the hazard severity and the risk control measures. Wherever possible these should be dynamically produced and task based. They should be available to the person carrying out the work who will reassess such things as environmental conditions and equipment state.