(a) Define the terms:
(i) earthing;
(ii) protective-earthing conductor.
(b) List two protective devices used in an electrical installation.
(c) State two advantages of high breaking capacity (HBC) fuse over
rewirable fuse.
The expected answers were:
(a)(i) Earthing is a method of connecting the neutral/star point of a
supply to the general mass of earth.
(ii) Protective earthing conductor is that which prevents hazard by
keeping the exposed conductive surfaces of a device at earth
potential.
(b) Any two stated below
Simple and easy installation
No maintenance required
No ageing effect
High breaking capacity
Extreme reliability
Coordination and discrimination can be achieved to a high degree
Low initial cost compared to rewirable fuse
More secured
The question was on Alternating Current Machines/Electrical Supply. It was
unpopular with the candidates. The candidates' performance was fair.
