Using the Multimeter - for a novice

[apogee]

I am fitting new lights in the kitchen, the lights for which have a switch by the inner house door and the back door. One of the 2 ceiling lights had a cluster of 5 cables coming out of the ceiling. Unfortunately in taking the cluster of wires out of the old fitting I lost sight of which came from which hole in the blocks. The lights in the next door room (2 x ceiling lights) now no longer work so I suspect that they were using this ceiling 'rose' as a junction box. (nor were any of the wires (except the earth wires) twisted together. So now I have 5 red wires and 5 black wires and 5 earth wires. One of the black wires has a red rubber collar on it. I have a multimeter in the house. I need to find out which is the live switch wire so that I can put it into a block hole all on its own, and put all the other red wires together in one block hole, all the other black wires into another one and all the earth wires in the last. So far so good. Can anyone tell me the procedure for using the multimeter to find out/check which of those many wires is the live switch wire? Which wires do I connect the black and red probes from the multimeter to and in which order, and when I find the right wire what should the multimeter readout be to prove that it is the one?

 

[bathjobby]

Normal good practice (but not always followed) is to indicate the switched live black with by putting a red marker, collar, tape, etc on it, so thats almost certainly your switched live.

 

[sparkyspike]

To check that this, (power turned off!) attach one lead to the bunch of reds and one to the sleeved black. With the meter set to continuity (ohms) turn on the switch. The reading should be very low if it's the correct wiring.

 

[Softus]

red

Brown?

 

[apogee]

Well done all - sorted