Safety procedures for electrical work in installations susceptible to unexpected sources of energy

Workers may still be at risk of electric shock even in de-energized electrical conditions of work.Hazards can be present if tasks are to be performed in dead installations susceptible to the harmful effects of unexpected sources of energy, originating elsewhere. This may be, for example, the case of work activity on overhead lines. The existence, as well as the severity, of the exposure to unexpected sources is generally unknown. The decision to deploy additional safety precautions should not be made under pressure in the field, and solely entrusted to the worker, but adequately planned. The alternative decision to adopt live working methods can solve those situations, in which the existence of unexpected sources of energy is uncertain. In any case, the intelligent and persistent adoption of live working methods, even applied to dead systems, could resolve suspect situations. This paper analyzes the three live working methods, the possible unexpected sources of energy, and related remedies, as for the technical standard EN 50110-1: Operation of electrical installations. The case study of an electrocution accident occurred during work on a dead overhead line, which most likely might have been prevented by adopting the bare hand working procedure, is also discussed.