This article explains how to install two-way lighting so that one light may be operated from two different light switches.
Rigging up the light and the ceiling rose, connecting to the lighting circuit, and connecting the primary switch is all carried out in much the same way as for one way lighting.
The difference between two way and one way is basically down to the switches and the link cable between them. The cable used for this link has an additional conductor. We use suitably sized three core and earth. The switches used will have two ‘ways’ and therefore three terminals each.
Switch off the power at the consumer unit for the circuit from which you are going to take the supply for the new light. If you have removable fuses at your consumer unit, switch off the power at the consumer unit and remove the fuse for this circuit.
Examine the cabling and identify the system which has been used. This may be a junction box circuit, or loop type circuit, or a combination of the two. For more information on this see our Lighting Circuits Guide.
If the wiring has no earth conductor, the services of a professional should be sought.
Locating the light
1. Decide upon the location for the new light and make a hole in the ceiling large enough to accommodate the cable(s). If possible, choose a position which enables the new ceiling rose to be screwed directly to a joist.
2. Otherwise, mount a wooden batten between the two nearest joists to provide the fixing.
Locating the two switches
3. Decide where you want each of the switches for this light.
4. Check that there are no cables, pipes etc buried below the surface.
5. Cut out the wall to mount the switch box in the same way as for mounting socket boxes.You may use a Surface Mounted Box, a Flush Mounted Metal Box, or a Flush Mounted Plasterboard Box. Primary switch
Primary switch
6. Feed a suitable two core and earth cable (see Lighting Circuits for details) from the position of the new light through to the switch. We will refer to this as the switch cable.
7. Feed a suitable three core and earth cable through from the secondary switch position to this box as well. We will refer to this as the link cable.
8. Remove a cable entry blanking piece from one of the switch box sides. If you are mounting the switch in a solid wall, you will have used a metal box and will need to line the cable entry point with a rubber grommet.
9. Feed the cables through, then secure the back box to the wall.
10. Strip and prepare the conductors of both cables ready for connection. Cut through the end of the outer sheath of each cable carefully using a pair of side cutters. Be sure not to cut into the insulation of the conductors.
11. Peel back the sheath of each cable to reveal the conductors and grip the end of the bare earth conductor with a pair of pliers. Draw the wire back through the sheath like a cheese wire.
12. Fold the excess back on each and trim with the side cutters.
13. Separate the conductors and trim the insulation of each back by about 1/2″ with wire strippers. For detailed information on this see our Cable Stripping Guide.
14. Insulate the earth conductors with green and yellow sleeving. This should be cut to length and fed over the conductor so that about 1/2″ is left exposed at the end to match the other conductors.
15. Tag the blue of the switch cable, and the black and the grey of the link cable, with brown sleeving. This serves to identify that all of these are live conductors.
16. Connect the brown of the link cable to the terminal labelled ‘C’ or ‘Common’
17. Connect the black of the link cable and the blue of the switch cable to the terminal labelled ‘L1’
18. Connect the grey of the link cable and the brown of the switch cable to the terminal labelled ‘L2’
Earth Connection
19. What happens with the sleeved earth conductor depends upon the fittings being used.
- Plastic switch and plastic mounting box – the earth conductor is connected to the earth terminal on the back of the mounting box if there is one. Otherwise, it is secured in a plastic terminal connector block and tucked safely out of the way. In this situation, some people trim the earth right back but this should not be done. If someone wants to fit a metal switch at a later date the earth will be too short.
- Plastic switch and metal back box – the earth conductor is connected to the earth terminal on the back of the metal mounting box.
- Metal switch and plastic back box – the earth conductor is connected to the terminal on the switch marked with the earth symbol.
- Metal switch with metal back box – the earth conductor is connected to the terminal on the switch marked with the earth symbol. An earth tail is also connected between here and the earth terminal on the back of the metal mounting box.
20. Double check your connections and ease the switch back to the wall folding the cable carefully into the box.
21. Secure the switch with its fixing screws ensuring that it is level
Secondary switch
22. Remove a cable entry blanking piece from one of the switch box sides. If you are mounting the switch in a solid wall, you will have used a metal box and will need to line the cable entry point with a rubber grommet.
23. Feed the link cable coming from the primary socket through, then secure the back box to the wall.
24. Strip and prepare the conductors ready for connection as before. Cut through the end of the outer sheath carefully using a pair of side cutters. Be sure not to cut into the insulation of the conductors.
25. Peel back the sheath to reveal the conductors and grip the end of the bare earth conductor with a pair of pliers. Draw the wire back through the sheath like a cheese wire.
26. Fold the excess back and trim with the side cutters.
27. Separate the conductors and trim the insulation of each back by about 1/2″ with wire strippers.
28. Insulate the earth conductor with green and yellow sleeving. This should be cut to length and fed over the conductor so that about 1/2″ is left exposed at the end to match the other conductors.
29.Tag the black and the grey of the link cable with brown sleeving. This serves to identify that these are live conductors.
30. Connect the brown to the terminal labelled ‘C’ or ‘Common’.
31. Connect the black to the terminal labelled ‘L1’.
32. Connect the grey to the terminal labelled ‘L2’.
33. Connect the green and yellow sleeved earth. The way this is done depends on the set up you have – as detailed above for the primary switch.
34. Double check your connections and ease the switch back to the wall folding the cable carefully into the box.
35. Secure the switch with its fixing screws ensuring that it is level.
Connecting the supply cable at the ceiling rose
36. Feed the other end of the switch cable, which you ran to the primary switch earlier, through the ceiling at the light point. Also feed through the end of a new length of suitable cable which will connect to the lighting circuit. Label these as ‘Switch’ and ‘Supply’ and ease them through the backplate of the new ceiling rose. Screw the backplate of the rose to the ceiling joist or noggin.
37. Strip and prepare the conductors of the supply cable.
38. Connect the brown (old cable colour = red) one to the terminal block marked ‘LOOP’.
39. Connect the blue (old cable colour = black) to the terminal block marked ‘N’.
40. Connect the green and yellow sleeved conductor to the terminal marked with the earth symbol but only secure loosely for the moment as another earth will also need to be connected here.
Connecting the switch cable at the ceiling rose
41. Strip and prepare the switch cable.
42. Connect the brown (old cable colour = red) to the terminal block marked ‘LOOP’.
43. Tag the blue with a piece of brown sleeving (old cable colour = black; old tag colour = red) indicating that it is actually the live coming back from the switch and connect it to the live terminal at the end next to the live flex connection terminal .
44. Connect the green and yellow sleeved conductor to the earth terminal. Ensure that both earth conductors are now firmly secured.
Lampholder connection
45. Prepare and connect a lampholder to a suitable length of flex. For more information on this, see our Lampholder Fitting and Connecting article.
46. Feed the other end of the flex through the ceiling rose cover and connect to the flex terminals.
47. Connect the brown (L) to the outer terminal next to the switch return conductor.
48. Connecting the blue (N) to the other outer terminal next to the supply cable neutral.
49. If your light fitting is metal the flex should also contain a Green / yellow (earth). This should be connected alongside the other earth conductors at the ceiling rose.
50. Ensure that the flex conductors are securly held in the retaining lugs provided.
51. Double check all your connections are correct, secure and have no exposed conductor showing. Fit the ceiling rose cover.
Connecting to the lighting circuit supply
52. The other end of the supply cable can now be connected to the lighting circuit.
53. You will need to decide the best method of providing the supply for this new light. The easiest way is by inserting a new junction box in the supply cable of the lighting circuit.
54. Unless the area where the junction box is going will be accessible, you will need to use a maintenance-free type. In this example, we are using a Wagobox maintenance free junction box.
55. Cut the cable of the lighting circuit next to where the junction box is to be fitted.
56. Strip and prepare the new ends remembering to sleeve the bare earth conductors in the usual way.
57. Strip and prepare the ends of the new supply cable as well.
58. Connect the brown Live (old cable colour = red) conductors together in a suitable terminal connector.
59. Connect the blue Neutral (old cable colour = black) conductors together in a suitable terminal connector.
60. Connect the green and yellow sleeved conductors together in a suitable terminal connector. In this example a cage clamp type terminal connector is being used. A push type connector would be equally suitable.
61. Secure the terminal connectors in the maintenance free junction box following the manufacturer’s instructions.
62. Secure the sheathed section of the cables in the cable clamps provided.
63. Fix the lid of the junction box and mount the box on a suitable timber using the bracket provided.
64. Double check all your wiring and connections.
65. Once you are sure that all work has been completed correctly, switch the power back on at the consumer unit. In the case of removable fuses, replace the fuse for the circuit, and switch the power back on.