How to trace a cable

[Chris Holmes]

I am wanting to disconnect/remove a cable, but at the nearest point I can get to it there are about 5 cables which conect to the same fuseway.

I have seen a Martindale cable tracer which injects a tone into the cable and allows it to be traced with a receiver. Does anyone know if these are sesitive enough to be able to distinguish between a signal which has come approx 10 feet from the exisiting socket position (where the transmitter would be plugged in), or from there another 10 feet to the CU and 10 feet back again?

Or have any other suggestions as to how to single out the relevant cable?

[Christian McArdle]

Assuming that this is some sort of radial circuit, turn everything off, especially including the main switch, the MCB and all appliances attached to this circuit.

Disconnect all the cables for this circuit at the consumer unit. Connect a resistance meter to the live and neutral of the other end of the cable you are trying to remove. It should be open circuit. If not, something bad has happened.

Then (using a helper, if necessary), short out the live and neutral of each of the disconnected cables at the consumer unit end in turn until the resistance meter shows a dead short. This is your cable.

Stick all the other cables back where they came from.

There's loads of other ways to do it, too, but this one involves having the power totally isolated, so should be safer than many.

Christian.

[Harry Bloomfield]

On 06/01/2004 Christian McArdle opined:-

Another alternative would be to make that circuit, the ONLY live circuit and then trace it with one of those volt stick gadgets. You just put the sensitive end of the unit close to a live cable and it will illuminate. No need to strip the cable etc., just get it near the right cable and it lights up.

[BillR]

I traced a cable in a wall by putting a load only on the output fed by that cable and used a small coil connected to an audio amplifier. There's a 50Hz field around the wire due the current flowing in it.

[Chris Holmes]

This sounds like it might be a possibility. Unfortunately this is nothing so simple as a radial circuit :=(( I did try the volt stick already, but it only narrowed it down to about 6 cables (though I did it "backwards" ie all the other circuits were on and the one I was interested in wasn't, so it's possible that some of them weren't actualy part of the circuit (Probably a ring main (fused at 30A) but with lot's of wierd stuff going on ("illegal" spurs etc etc. I am thinking of converting it into a number of radial's on a new split load CU with MCB's.