Important terms/topics covered in this chapter: 

■ Emergency switching Rapid cutting off of electrical energy to remove any hazard to persons, livestock or property which may occur unexpectedly

■ Isolation Cutting off an electrical installation, a circuit or an item of equipment from every source of electrical energy

■ Mechanical maintenance The replacement, refurbishment or cleaning of lamps and non-electrical parts of equipment, plant and machinery

■ Switch A mechanical switching device capable of making, carrying and breaking current under normal circuit conditions, which may include specified overload conditions, and also of carrying, for a specified time, currents under specified abnormal conditions such as those of short circuit