The problem of electrical workers being injured or killed by electrical arcs and blasts is the most significant safety issue in the electrical industry today. The principal hazards associated with arcs and blasts include thermal burn injuries and physical trauma from the blast concussion and flying projectiles caused by partially melted components being propelled by the force of the blast.

It is noteworthy that "engineering for safety" is a relatively new development in the Electrical Engineering realm. Obviously, Electrical Engineers considered Safety in the past but Arc-Flash Hazard Analysis (AFHA) represents one of the first times were Safety IS the focus rather than an ancillary consideration in the engineering process.

It is also important to understand that the focus of AFHA is to mitigate hazards and not merely to select Flame Resistant (FR) clothing. Many Electrical Engineers have used the methodologies discussed in this paper to calculate the "heat" associated with electric arcs but then used that information only to recommend that Electrical Workers wear higher levels of FR clothing. The appropriate approach would be to first exhaust reasonable attempts to make engineering changes to the system to reduce the "heat" and THEN select the appropriate FR clothing for the Residual Risk that cannot be adequately controlled through engineering interventions.

History of AFHA

The electric utility industry was the first non-academic group to study Arc-Flash (AF) hazards when they noted that high voltage workers often received the most severe burns from their clothing igniting and continuing to burn long after the initiating arc had extinguished. In particular, "man-made" fibers such as Polyester, Nylon and Rayon were known to melt and "stick" to the worker's skin following an AF and this resulted in burns many times worse than had the injured worker been wearing no clothing at all.

Duke Power Company began high-energy testing of fabrics in 1986 following a highvoltage AF accident. Duke Power management initially tried to find studies relating electrical arcs to burn injuries but they noted that most studies related to house fires or other fires caused by common combustibles. The problem with these studies was that the heat produced from a house fire increased very slowly in comparison to that caused by an electrical arc. The temperatures of an arc could reach values many times hotter than the surface of the Sun in less than 0.5 seconds and this very rapid heat gradient had never before been studied in relation to burn injuries.

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