Features of electric arc accidents and use of protective clothing in Finland

Abstract

An electric arc produces a high level of thermal energy which ignites normal materials and causes burn injuries to the workers nearby. The amount of energy released in an electric arc depends on the type of electrical installation, and is determined by the following parameters: current, duration of the arc, length of arc, distance from the arc and source voltage. The effects on the human body thus depend on the energy, and the kind of clothing being worn. This study analyses 25 electric arc accidents that occurred in Finland in 1996–1999, and the role that protective clothing played in them. The study also investigates the current usage of protective clothing and other personal protective equipment, as well as the implementation of technical measures and training in decreasing the risk of electric arc accidents in power stations and transmission utilities. Most of the accidents studied took place in a low voltage installation with a nominal voltage of 400 V. However, the accidents that occurred in a medium voltage installation were more serious than those that occurred in low voltage installations. Workers who did not wear flame-retardant protective clothing encountered accidents that led to bodily injury more frequently. Workers who wore garments that are flame-retardant and do not break open in an accident, sufferered less serious injuries. In order to adapt the protection level of the clothing to the true need for protection, different levels should be defined rather than setting only one, fixed level of protection. Companies should analyse their work sites to assess the occurrence of risk and the kind of protection that is needed. Technical measures should be implemented first. Training should aim to change attitudes so that intentional risks will not be taken, and that personal protective equipment will be used when required.