For the benefit of all posters & some responders, to reduce errors.
Circuits are either;
RADIALS = single cable from Consumer unit not returning, or
RING CIRCUITS (NOT ring MAIN)=starting and finishing at consumer unit.
[A ring MAIN is a HIGH VOLTAGE distribution system going between substations].
Fused spur =old name for Fused Connection Unit.
RCD (Residual Current Device)=old Earth Leakage Circuit Breaker.
MCB(Miniature Circuit Breaker)= overload device in place of old fuses.
RCBO (Residual Current Breaker plus Overload).= combined RCD+MCB.
Diversity=not all load on at same time eg cookers.
Competant person = one having sufficient technical knowledge, practical skills & experience for the nature of the electrical work undertaken so as to prevent danger to himself & others. ( a long one but from IET regs.
& from Electricity at work act -law).
Many more definitions but these seem to be misunderstood most.
regards All,
SPARX