Background
Over the five years from 2011 to 2015, 13 workers on Western Australia mine operations received injuries from arc flash incidents that required medical attention and were placed on restricted duties or lost time.
In the last three years, Resources Safety has published seven Significant Incident Reports covering arc flash incidents. Across industry there appears to be a lack of awareness of arc flash hazards and the need to put controls in place.
Summary of hazard
An arc flash is a dangerous condition associated with the uncontrolled release of energy caused by an electric arc. The temperature of the arc can be as much as four times that of the sun’s surface, and it can vaporise a copper conductor to several thousand times its solid volume in a fraction of a second. The resulting explosion, or arc blast, can seriously harm people and damage equipment.
Contributory factors
Arc flash injuries usually arise when work is being conducted close to energised equipment without effective controls. For example:
- workers not wearing appropriate and adequate personal protective equipment (PPE)
- electrical equipment and cables not tested for insulation resistance prior to energising
- risk assessment not undertaken for a change in the isolation process
- work performed outside of the safe work instruction or procedure
- switchgear not subject to an adequate maintenance, test and repair program
- electrical drawings not updated to reflect changes to the electrical installation
- protection settings not calculated and set correctly.