Domestic Electrical Installations 35
Equipment Non-fused spur Cable size not less than ring
Fused spur
L
Fused connection unit 13 A maximum
E
Junction box N
Cable size not less than ring Non-fused spur
Cable size not less than ring
Non-fused spur
Local protection and switching
Permanently connected equipment
FIGURE 2.22
Ring final circuit.
Power and lighting The cable used for these applications will predominately be of the flat twin with cpc variety (6242 Y) or flat three-core with cpc (6243 Y) (Figure 2.23). The use of steel or rigid PVC conduit containing single-core conductors is rare in domestic premises, with the exception of flats or apartments with solid floors and ceilings and some older properties. As we have seen, modern 6242 Y cable has brown and blue insulated conductors, the blue needing to be sleeved brown when used as a switch wire in lighting circuits. However, a 6242 Y cable is