Reconnecting wiring after removing light

[Andy]

Hi All,

I have just removed a light in our hallway that we no longer want. Unfortunately - and I bet you know what I'm going to say! - I didn't make a note of the existing connections before removing the light

[Martin Angove]

Absolutely right... you know, this question comes up so frequently it should really be in the FAQ... oh...? Well, there are several archived answers on google groups anyway...

If you have terminated all four wires (2 red, 2 black) separately then it seems to me as if this is the last light on the circuit - if not there should have been another red&black and terminating them separately would have meant some other lights not working.

This is the most probable scenario, but be absolutely sure before doing anything silly:

One red and one black are the incoming circuit, live & neutral.

The other red and black are the live feed to the switch and the "switched live" return from the switch.

The trick is to identify this second pair. The easiest way is with a multimeter which has a continuity beep (typical cheap Lidl job will do nicely).

First, turn *all* the power off at the main switch. Check that the lights don't work any more.

Turn the appropriate switch "on" and use the multimeter to determine which pair of wires is now joined together - in other words, one combination of red & black should produce a "beep". This is your switch pair - mark both wires before you lose them.

When refitting the lamp, the two reds should be joined together, but not attached to the bulb in any way (incoming live and switch feed). The switch return (black) should go to the brown wire feeding the bulb and should be marked with red tape or sleeving, and the last black wire (circuit neutral) should go to the bulb's blue wire.

I have a couple or reservations though:

1: You do not mention any earth wires (usually bare copper and should be covered with green & yellow sleeving). 2: You do not say that the red and black wires are sheathed together into cables (i.e. grey or white "twin & earth").

Both of these observations, if true, imply that the wiring system is probably quite old and I would strongly advise you to have it checked thoroughly by a competent person. The lack of an earth could be dangerous if you are fitting lamps which require an earth (not all do).

HTH.

Hwyl!

M.

[Andy]

Thanks! There are no earth wires - but both red and black are inside a grey cable. The removed lamp had no earth either tho'. We've also still got an old fuse box - uses fuse wire! - so having thought about it I'll get some quotes for re-wiring, better safe than sorry with electrickerry methinks.

Thanks again Andy