Converting one-way light switch

[antgel]

Hi all,

I have a room with two ceiling lights switched on one switch. Is it difficult to convert this to a double switch? Logically, how do I modify the wiring?

Antony

[bigcat]

google 2 way switch to find a pic of the citcuit, then youl see Or Maybe Ive misunderstood

NT

[:::Jerry::::]

This group really is showing up the rational behind Part P in the last few days... :~(

[Lobster]

I think so - the OP's referring to a two-gang switch I think! (or maybe

*I've* misunderstood!?)

Antgel: a two-way switch is one which lets you control a light from two locations, typically on the landing (ie up and downstairs); a two-gang switch is a faceplate which has two switches on it (the switches could be one-way or two-way!)

To convert to a one-gang to a two-gang switch isn't entirely straightforward I'm afraid; basically you'll need to replicate the cables going to the original switch. Imagine if you wanted to do the same job, but installing another one-gang switch a couple of feet away: that would be exactly the same level of work required.

So without going into all the details, assuming you have conventional wiring, the main requirement will be for a second cable to be wired into the switch, up the wall and into the ceiling space above the light fitting. Do you need more info, or is that enough for you to know it's not going to happen?!!

David

[antgel]

Indeed I am referring to a two-gang switch. And it could very well happen. I'm in the process of hacking my ceiling to install projector cables anyway.

So you're saying that I need to run two new cables, one from the switch to each of the two lights?

[Sparks]

What cables are in the switch already? If there is just a single cable (Containing a black or blue, red or brown and bare wire) you will need to run another one of these from the switch into the ceiling.

Can you get access to the light fittings from above?

Sparks...

[Lobster]

Also, what sort of fittings are there presently - ceiling roses or something different? If you've got ceiling roses, how many cables are wired in to each one? I'd expect one to have several (call this light "A") and one to have just one cable (light "B") because B will simply be piggy-backed on to light A, so that it goes on and off at the same time as A.

You need to get a cable to run from light "B" all the way down to the switch; and finally the 'piggy-back' cable connecting to light "A" needs to be wired differently in order to energise light "B" continuously rather than just when light "A" is switched on.

If you don't have roses, how many cables come through the ceiling - just one for each fitting? If so, the connections will presumably be in junction boxes above the ceiling, instead, and it's not so immediately obvious which light is A and which is B.

David

[antgel]

We all had to start somewhere. The fact that I'm asking shows that I want to do it properly. I assume you were born with an encyclopaedic knowledge of electrics.

[John Rumm]

How do you figure that?

I would say the *group* is providing the correct answers to this question everytime someone asks it.

[fred]

In article , antgel writes

Indeed you do, don't take it personally, a quick google on that poster's id shows a tendency towards arrogance over helpfulness in posts to this group; killfiled by me long ago.

[:::Jerry::::]

Oh yes I agree, but sometimes those question and answers are coming

*after* work has started, when the person doing the work obviously doesn't have a clue to start the job - no problem with people asking how to do the job, I just wish that they would ask first and be realistic about their abilities...

[dave stanton]

I bet he did his first house rewire when he was 2....

Dave

[John Rumm]

Perhaps you missed part of the thrust of my question, i.e. since what the OP is doing is outside the scope of part P anyway (i.e. a minor work) how is it supposed to help? Part P makes the law into an ass whichever way you look at it.

You do raise an intersting question however: How are we to be "realistic" about our abilities without knowing where the limits of those lay? How do we test where those are without actually attempting to do something and reaching them? Surely reaching the limits of ones abilities is not a significant event in itself, what we do next however is significant (e.g. seek help, give up, press on regardless). In an ideal world we could research every step of a job from start to finish before starting, but the real world has a habit of not being so deterministic.

[al]

Enough already with the "past his abilities" stuff! ;P

I'm not entirely clueless and do understand basic safety with electricity. I also know a fair bit about electricity at a slightly lower level from an engineering degree many years ago. From that, I know I'm not likely to set the neighbourhood alight by connecting a cable in a lighting circuit to see what happens. I'm also not dumb enough to leave something in place if I don't think it's right. Thus my original post.

The only reason I've run into difficulties here is because of impractical house design and the impossibility of doing something right without destroying my kitchen :(

a

[:::Jerry::::]

encyclopaedic

Five actually, I could get my hands were my father couldn't get his own.....

But I don't call my self an expert by any means, although I've done quite a bit of both domestic and 'industrial' [1] 3ph wiring - the one thing I always do if I don't understand things is ask first before I risk making mistakes that could prove fatal to others.

20 odd tears ago in a voluntary organisation.

[:::Jerry::::]

coming

asking

Isn't this work in a kitchen area and thus comes under Part P ?

attempting to

however

finish

There does seem to be some confusion about basic feeds, switched feeds and (neutral) returns though, if someone can't get to grips with what needs to be present already were they wish to extend the circuit from that to me suggests that they need to learn considerably more before they start altering existing wiring.

[al]

Again, this came around out of trying to add a second light where one was needed while that side of the ceiling was being re-decorated. Unfortunately the other side wasn't and I really don't want to destroy it. There is no part of the lighting loop available to me at all to take feed from for this switch. I therefore dangled the cable down, connected it up, tried it ... and it didn't work. I disconnected it and posted here to make sense of what I'd done and why it didn't work - which I now perfectly understand.

My only option now really is to take a fused feed from the ring main junction box by my boiler, which I can reasonably well conceal up to the switch after digging myself a little trench in the plaster ... which I fortunately haven't papered over yet in that area.

a

[:::Jerry::::]

before

Unfortunately

That is my point, you tried something that basic knowledge said could not be done, you shouldn't have even tried it - what if this 'exercise' had not be as harmless as you thought or indeed it turned out to be ?

My point is, you should have posted here first surely, but then basic circuit knowledge should have told you all you need to know...

Or consider doing the job correctly, irrespective of what need redecorating...

[:::Jerry::::]

before

Unfortunately

That is my point, you tried something that basic knowledge said could not be done, you shouldn't have even tried it - what if this 'exercise' had not be as harmless as you thought or indeed it turned out to be ?

My point is, you should have posted here first surely, but then basic circuit knowledge should have told you all you need to know...

Or consider doing the job correctly, irrespective of what need redecorating...

[BigWallop]

So glad you said it twice. I missed it first time. :-)