Part 1 of this series of articles introduced the requirements of the Australian Work Health and Safety Act and Regulations to identify reasonably foreseeable electrical hazards including arcing hazards. It continued to show how the Australian WHS Regulations requires management of these risks so far as is reasonably practical using a hierarchy of hazard control measures.
It explained that whilst arcing faults normally last less than a second, they develop over time from an insulation breakdown to single-phase, three-phase and two-phase-and-earth faults with amplitudes much higher than load currents that move away from the source of supply.
Parts 2 and 3 of this series described how an arcing fault consists of up to three live electrodes with plasma jets ejected from near where the arc columns attach to the electrodes. The plasma arc jets are then inter-connected by filamentary constricted arc columns. All the constricted filamentary columns lie inside a conducting region carrying diffuse currents that are made up of Copper (Cu), Oxygen (O) and Nitrogen (N) atoms and ions. The nearly invisible extremity of the conducting region is referred to as the molecular boundary where the radiation density falls to a level where molecules can survive and conductivity collapses. This leaves a decaying plasma cloud that causes most of the severe burns during arcing incidents.
The following Part 4 of this series describes how arcing faults react with human beings and their personal protective equipment.