Another ceiling light question.

[Unclebill]

We are refurbishing a room and on trying to replace old ceiling light I found that there are only two wires sticking out of a metal tube conduit both of which are red. The new fitting has a transformer so I'm assuming that it should be wired as the instructions suggest, live to live, neutral to neutral and earth to earth.
Only problem is there is no earth and, as stated before, both cables are red.
How do I find out which of the two wires go where and how do I fit an earth?
All suggestions gratefully received!!!

 

[LukeScotty]

I could be wrong but if theres no earth, aren't you meant to fit class 2 fittings? and with the 2 red cables, I'm not too sure, maybe one of them is neutrel and hasnt been flagged up? they could ran out of cable and only had red/red twin?? I'll let the experts comment on this!! hang on tight!!

regards luke (please correct me if i am wrong)

 

[Unclebill]

Is it possible that the two red cables are actually only one cable which has been cut to wire the old style light fitting?

 

[TonyM58]

Uncle Bill

it is likely that the metal conduit is being used as the earth, this is standard practice with metal conduit or trunking

Assuming you have a test meter, and assuming that one of the reds is an unsleeved neutral, then measring between both reds will show 230V, measuring between one of the reds and the conduit will show 230V, this is your phase conductor (and also proves the conduit is earth), then measure the other conductor to conduit should show 0V, this is your neutral and should be sleeved black.

Obviously working safely, etc etc

regards

Tony

 

[Unclebill]

Thank you Tony.
One point, should these measurements be made with the light switch on or off (probably a very stupid question!!)
Also, what can one do when there is no measurement equipment available??
Yours
Bill

 

[TonyM58]

Unclebill

The light switch would need to be on to power up the circuit. i would suggest terminating the cables in chockblock so they dont touch

Not much can be done without a meter. For a simple voltage test like this, one of the 10 quid argos digital multimeters would be sufficient.

You could also use a test lamp, but this would not give an accurate result of whether or not the steel conduit was properly earthed

regards

Tony

 

[Unclebill]

Thanks again Tony,
I have bought a multimeter so will give it a go,
Bill

 

[Unclebill]

Multimeter worked a treat and the conduit pipe is the earth. Used an Ezybond earth clamp and the new fitting is up and running. Thanks to everyone who helped.
Bill

 

[ian.settle1]

How old is house? Because if it is the old slip conduit I would pull in a cpc soon would not really to much as earth.