Best way to trace wiring

I will soon be refurbishing shower room. First thing I want to do is replace the lights, currently 4 x halogen spots but will replace with a central mounted LED fitting. The light switch is located outside at the door so would I be safe to assume it will go straight up and enter the ceiling void around that point.

Some more assumptions: Is it likely that there will be a block connector (or similar) to then take the feed to the halogens. Can I then just disconnect this feed and use for my new fitting.

I suppose my main point is how do I find and trace the wiring to make the changes, without ripping the ceiling out. I have ordered one of those cheap borescope thingies which should arrive in a couple of days but dont know if it will be of any use.

Reply to
ss
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The normal way would be to take the existing light fittings down and check continuity/which goes where, with a meter. Also the wires can be jerked and see if the other end moves or it rattles on the ceiling. The physical route of the wire is neither here nor there.

You might be able to"fish" he old wiring to the new position if they are unsecured (to the ceiling joists.) If they are secured (clipped) then some damage is probably unavoidable.

Reply to
harryagain

I use one of these with very good effect. Lets you follow wires in the ceiling easily, but make sure that the circuits are powered off when you do it:

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Andrew

Reply to
Andrew Mawson

Its a fair assumption...

You would expect to find a junction box of some form. That will usually contain the power in, out and switch wires, plus one (or more) feeds to the lamp fittings. (depends a bit on if they are LV halogens with a transformer or mains powered ones)

See:

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Yes. Obviously you want to avoid having old sections of live cable floating about in the ceiling unused - so you would need to disconnect them at the junction box.

You should be able to do a fair bit just with a resistance meter.

Reply to
John Rumm

I have one of these much cheaper ones, it works fine as long as you can touch the tip on the insulated conductor.

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Not sure if Andrew might be talking about following wires from the other side of the plasterboard, if you see what I mean.

Reply to
newshound

Yes I am. A sparky working on my house refurb failed to connect two smoke alarms into the common circuit for them all - only discovered when floors and ceilings finished. After I'd fired him (!) I traced his wiring up a partition wall, across a ceiling and under 300 mm of insulation in the loft, where he'd left the unterminated coil of wire, all without opening up any holes in walls and ceiling.

Andrew

Reply to
Andrew Mawson

Good result! I must check out the "range" of mine, but most of my ceilings are lath and plaster.

Reply to
newshound

You haven't said whether they're mains or 12v halogens. If 12v, there will be a transformer powered by the mains, with 4 directly-connected outputs going to the halogens, or maybe with one output and a 4-way junction box.

The halogen lamps will have sprung arms holding them against the ceiling. You should be able to pull them down and feel around in the void (or look around with your new toy) to work out what's going on.

Reply to
Roger Mills

An induction look receiver will pick up mains borne interference from a cable through plaster, or you could de-energise the circuit and use a telecoms toner.

I discovered several sockets in my kitchen that had been plasterboarded over using this method. :-)

Owain

Reply to
spuorgelgoog

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