There are two principal methods of wiring lighting circuits in the home: the loop-in ceiling rose method and the joint box method, used mainly for surface wiring where there is no access for cables above the ceiling and for wall lights where looping in the absence of ceiling roses can be difficult.
The loop-in method.
The basic component is the loop-in ceiling rose which serves as a circuit joint box as well as providing the supports and terminal connections of the pendant flex. To wire the circuit a twin and earth PVC sheathed cable is run from a 5 A (amp) fuseway in the consumer unit to each of the lighting points (ceiling roses).
Then, from each lighting point, a length of the same cable is run to the appropriate switch. Where a light is to be controlled by two-way switching, a three-core and earth cable is run from the first switch already wired to the position of the second switch. The joint box method. The twin and earth PVC sheathed cable is run from the fuseway to a series of four — terminal joint boxes — usually one for each light and switch. From each joint box are run two twin and earth PVC sheathed cables. One goes to the lighting point; the other to its switch.
Wiring an 8-point lighting circuit
Wiring is by the loop-in method. Materials required: A quantity of 1 sq mm flat twin and earth PVC sheathed cable. The total quantity varies with the size of house and positions of lights. Approximately 10 m (11 yards) of 1 sq mm flat three-core and earth PVC sheathed cable. About 10 ft (3 m) green PVC sleeving. 8 loop-in ceiling roses. 7 one way switches. 2 two-way switches. 9 one-gang switch boxes, comprising plastic for surface mounting and plaster-depth metal boxes for flush fitting. Plus cable-fixing clips and wood screws for fixing boxes, ceiling roses etc.
Variants. Where dimmer switching is required add 1 dimmer and delete 1 switch. For two-way switching in a bedroom, delete 1 one-way switch and add 2 two-way switches, one of which can be a ceiling switch over the bed. For every special lighting fitting delete 1 ceiling rose and add 1 mounting box. For joint box wiring add 1 four-terminal box for every light so wired.
1. Decide the positions of all lights and switches.
2. Pierce a hole in the ceiling at each lighting point for passing the cables through and one hole above each switch position.
3. If re-replacing old wiring, remove this first, whether or not existing lighting positions are to be used.
4. Decide on the routes for the cables.
5. Raise floorboards and drill joists.
6. Run the cable from the consumer unit to each lighting point in turn, allowing about 6 in. (15 cm) of cable for connections.
7. Run a cable from each light to its switch.
8. Run a three-core cable from one two-way switch to the other.
9. Fix cables.
10. Fix and connect ceiling roses and lighting fittings. 1
11. Fix switch boxes to walls 1
12. Fix ceiling switches. 1
13. Connect and fix wall switches. 1
14. Connect main circuit cable to 5A fuseway in the consumer unit.