Fluorescent tube fittings, like many other types of light fitting, only have a connection terminal for the Live, Neutral, and Earth. Unlike ceiling rose and pendant lights, there is no facility for running the switch cable from the fitting itself. Provision of the switch cable can therefore made at the junction box connected into the lighting circuit.
Fluorescent tube fittings are commonly used for utility lighting in places such as garages, workshops and lofts. In this example, a fluorescent tube fitting is being installed in an upstairs room and the junction box used is fully accessible. A standard screw terminal junction box can therefore be used where the connections are made to the existing lighting circuit and for the switch cable for this light. If a junction box will not be accessible, a maintenance free one should be used instead. More information can be found in our Junction Box article.
1. 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.
Fluorescent Tube Fitting
2. Decide on the location for the new tube fitting. Remove the cover and determine which of the fixing holes in the base of the unit will be most suitable. You should use a minimum of two fixings – one towards either end of the fitting.
19. Strip back the outer sheath and prepare the conductors ready for connection. 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.
24. We’re using a plastic switch and a plastic mounting box so the sleeved Earth conductor is connected to the Earth terminal connection at the back of the box. Arrangements for the earth conductors vary according to the type of switch and mounting box. Full information on this is set out at the bottom of the article.
Connecting the Junction Box
27. We now need to connect up the junction box to provide a switched supply to the new light. Double check that the lighting supply cable has been isolated at the consumer unit as mentioned at the beginning of this article. At the point in the attic where the light cable and switch cable have been run back to the lighting supply circuit, cut the cable.
30. Mount a four terminal junction box of suitable rating. This can simply be screwed to a joist or, if needs be, fit a wooden batten to support it on. As mentioned earlier, a maintenance free junction box must be used if the location will not be accessible later. In this example the area is fully accessible.
35. Make sure that all connections are fully secured with no exposed conductor showing. Ensure that there is no unsheathed cable outside of the junction box. Replace the junction box cover and secure. The cover of most screw terminal junction boxes can be rotated to provide the required number of cable entry points.
Earth Connection at the Switch
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.