Wierd wiring problem

[tonyenkiducx]

I've recently bought a house that has, to put it mildly, been put together by a ****witt. The problem I have at the moment is with my kitchen light. There is a 3 core cable coming to the light switch, with black, red and brown cables coming out of it, and an extra red cable twisted onto the red from the 3-core that splits off to power a plug socket underneath it(The twisted section of cable goes directly into the light socket).

Not being sure what was going on I tested all the cables with the multimeter, and figured the reds are live(Not always a guarantee in this house), black is neutral and the brown is earth. Unfortunately when fastening it all back in, the brown was disconnected from the earth connection on the switch, and was floating around the back of the box(I'm 50% sure it wasn't touching anything, but it could have touched the screws fastening the back of the front plate on). The switch is a nickel coated metal switch, with a push-on face plate(I.E. no screws on the front). I checked the switch itself and there is a very clearly defined layer of thick plastic between the cable section and the switch itself. So I'm sure there was no current passing from the live and neutral to the front panel.

When I fastened it all up, it worked fine with no problems. But after a few hours when I turned the light on, I got a fairly substantial shock from the switch. Not enough to harm me, but I had to go sit down for a bit.

Now Im wondering exactly what went wrong, and how I can avoid it in future? Was it just the earth being disconnected that did this?

 

[Adam_151]

A) Red, black and brown ? ...
Weird cable, and you don't mention a separate bare earth?
So could it possibly be old colour code Twin and earth (red, black and bare) with a bit of brown sleeving of somekind placed on the earth?

B) You seem to have a neutral at the light switch, but not a switched live? unless you are just mistaken? Or you have both a switched live and a neutral but no earth because what you called earth was really something else... which would account for the shock....

C) You shouldn't have anything between a light switch and a power outlet, how many wires is there between the two? just a the live? Is it the lights that stop working when you disconnect this?

D) A photo would help immensly, do you have a digital camara? could you take one and upload it to a free image host site and link to it from here?

 

[scousespark]

How old is the house.
Sounds like you may have very old wiring in there (pre 16th edition).
If so you will probably find you have no earth conductor in your lighting circuit, and you should replace the metal fronted switch with a plastic one.
Given you received such a shock, I'd strongly recommend you get a spark in to check it out.

 

[tonyenkiducx]

Thanks for the quick reply Adam.

A)The brown cable is sheathed brown all the way down the cable, I had to cut some out to make it reach the new switch. I am also color-blind, but Im 99% sure its brown.

B)Not sure.. There is a ?mystery? switch at the bottom of the stairs that would appear to be a second switch, but it has no current running through it. They had replace the switch in the living room with a dimmer, which might be a reason for the second switch being disconnected. I was fairly stupid and didnt keep a record of what was connected to the old dimmer before I binned it.

C) The guy was a total bodger. The live goes to the plug socket, but the other cable back from the plug socket just dissapears into the wall, and hes concreted over it, so I cant check where it goes. I presume hes ringed it round somewhere else, because neither the light nor the socket interfere with each other.

D) Will do this tonight and post them, stuck at work at the moment.

I realise I'm not being a lot of use, but hopefully the picture tonight will spread more light(har har) on the problem

 

[tonyenkiducx]

Ohh, and one of the maintenance guys at work suggested because the earth was disconnected, it might have been static build-up. I did also remove the carpets on the day this happened(Before I got the shock funnily enough). Does this sound likely?

 

[scousespark]

Your OP is a bit confusing. Have you had a rewire, and why did you have to open up the switch? Do you have a lighting problem.

Sounds like a real botch up, but your photos should help clarify things.

If you've had somebody in to rewire, can you not get them back in to sort the mess out. This sounds like the type of situation Part P was designed to stop and most work in a kitchen is notifiable under Part P.

As for the cause of the shock, anything that gives you a belt such as you described should be checked by an electrician.

 

[tonyenkiducx]

The only work I've done on this particular switch is to remove a dimmer, and replace it with a normal light switch. No other wiring work has been done on the house while I've been there. The previous owner was a builder, and hes done a lot of the work himself, so you can guess what a mess it was. 3 months after moving in and I'm only just done replacing all the botched plastering and pipework.

For example, we had two sets of power cables going upstairs from the fusebox, one for a storage heater and another for the plugs. I disconnected the storage heater from the fuse box because I didnt want it any more, and went and unwired the heater and took it away. I went back to tape up the cables, and out of habit I ran my rubber-handled screwdriver across both cables(Something my dad always said to do, even if your sure the cables are not live), and they bloody sparked! Well after a couple of hours of searching and following cables, I found he'd wired both the plugs and the storage heater into the same splitter in the loft, and then split them back off again. So no matter which one I'd switched off, they were both live. Could have easily ended up a charred corpse over that one.

While I'm at it, how much do you guys reacon it would cost to get a "spark" to come and just look at the electrics and make recommendations?


Ohh, and I think I know whats confusing about the plug.. If I disconnect the live(red) cable coming from the plug socket, from the light cable, the plug socket completely stops working. But switching the lights on and off makes no difference to the plug socket working.

 

[tonyenkiducx]

http://www.enkidu.cx/wiringpicture.jpg

I hope thats understandable.. I dont have a decent camera, so its just with my phone.

 

[JohnD]

Do the wires appear to be hard, glossy plastic, or might they be old rubber?

Are the wire cores a single strand of copper, or are they white metal and/or stranded?

The one marked brown might be the earth conductor. These are usually not insulated inside the cable sheath, and you push plastic sleeving (green and yellow) to cover the copper wire, inside the switch enclosure.

Does the brown sleeving appear to be loose, as if someone had run out of green and yellow and pushed on a spare bit of brown (p.s. I think it might be dark green - as you are colourblind it may help to get someone to have a look for you)

 

[tonyenkiducx]

They are old rubber wires. There all stranded, and appear to have been twisted and manipulated a lot.

The brown cable is definately insulated inside the sheath, I cut a fair bit of the sheath of myself and it was all insulated.

I just asked my wife to look(Good idea), and it is dark green Sorry about that.

Ohh, and on your advice, I have disconnected the plug socket from the light switch. I guess I'll have to run some new cable down there.

Tony.

Do the wires appear to be hard, glossy plastic, or might they be old rubber?

Are the wire cores a single strand of copper, or are they white metal and/or stranded?

The one marked brown might be the earth conductor. These are usually not insulated inside the cable sheath, and you push plastic sleeving (green and yellow) to cover the copper wire, inside the switch enclosure.

Does the brown sleeving appear to be loose, as if someone had run out of green and yellow and pushed on a spare bit of brown (p.s. I think it might be dark green - as you are colourblind it may help to get someone to have a look for you)

 

[JohnD]

They are old rubber wires. There all stranded, and appear to have been twisted and manipulated a lot.

Aha!

Sorry mate... time to rip them all out and start again

 

[tonyenkiducx]

Ohhh noo, you evil electrician you. There behind a concrete wall thats been freshly plastered.. Is it really necessary? And having lived in a building site for 4 months, I'm getting to the point where D.I.Y is more like torture than an investment now. Could it be left for a few years?

Tony.

They are old rubber wires. There all stranded, and appear to have been twisted and manipulated a lot.

Aha!

Sorry mate... time to rip them all out and start again.

 

[JohnD]

Is it really necessary? YES

Could it be left for a few years? IT ALREADY HAS BEEN - PROBABLY 40 OR MORE

Sorry.

You might be lucky and have conduit or capping that you can poke the new cables or cores down.

There are people who will say that old wiring is OK as long as it isn''t giving problems and you don't touch it... but neither of these is true in your case.

 

[tonyenkiducx]

Im obviously not explaining myself very well. To replace the cabling would require me ripping out at least 2 solid concrete walls, that I have just paid an inordinate amount of cash to get plastered. It would also mean me sitting on a mattress in my box-filled bedroom for another 2 or 3 months while I find the large pile of cash I would need to get this work done, having allready done this for 4 months and gone stir crazy.

Now I ask again, is this really really necessary, or is there a quick temporary fix I can do? (Something along the lines off, hide the cables, and fit new ones with trunking)

 

[ban-all-sheds]

Well - that fix will turn out to be anything but temporary, but if you don't mind surface trunking then it's OK to disconnect the old wiring, leave it in place, and rewire using surface trunking.