Protection against indirect
contact
Exposed-conductive-parts used in the manufacturing process of an electrical
equipment is separated from the live parts of the equipment by the “basic insulation”.
Failure of the basic insulation will result in the exposed-conductive-parts being alive.
Touching a normally dead part of an electrical equipment which has become live due
to the failure of its insulation, is referred to as an indirect contact.
Various measures are adopted to protect against this hazard, and include:
b Automatic disconnection of the power supply to the connected electrical equipment
b Special arrangements such as:
v The use of class II insulation materials, or an equivalent level of insulation
v Non-conducting location, out of arm’s reach or interposition of barriers
v Equipotential bonding
v Electrical separation by means of isolating transformers