More light switch wiring in a loft

[RedWinged]

Hi folks,

I asked previously about wiring up a light switch. Thanks for the advice everyone - turned off the mains, checked it was off with a voltage tester, had a new face plate ready and everything...

The switch box has a cable coming into it, and then another cable coming out going up to the lamp. However, inside the switch box, the two red wires are connected (sort of...) into the actual switch, one in each terminal, the two black wires lead into a mess of electrical tape, and the two earth (hope that's right? green/yellow) are sort of near each other, both with sheathing hanging off, not connected to anything. This doesn't seem right at all, so I just put it back how it was (the red wire had come out the switch, I just placed it back as I put the screws back in the switch box). This has made the light work again, but I'm not in the least bit happy with it. How could I clear this up?

I'd guess I could get a terminal block or something to connect the two black wires just to tidy it up, but it's the earth that concerns me, and I'm not sure it's even wired correctly but don't know how to check for polarity or anything.

Cheers for any advice!

[Andrew Gabriel]

Connect the earths in another terminal block, or on the earth terminal in the back box if it has one.

[Gazz]

It's not wired up 'correctly' properly the power should go to the light bulb socket, then a twin core cable with 2 red wires in it should come from the light bulb socket to the switch,

But the person who put your light in did it the easy/bodge way, it'll still work tho, but of course get some terminal block and connect the black wires to each other properly with terminal block, and do the same with the earth wires (but the earth wires arent really needed for a light if it's a plastic housing, nothing to connect it to in the light bulb socket)

There's no polarity as such on mains wiring as it's alternating current, meaning is changes polarity 50 time s a second, but red or brown is live, black or blue is neuteral, and green and yellow is earth,

as long as you keep red wires connected to red wires, and black to black you'll be ok,

[Harry Stottle]

Unless someone has used a black/red cable for the switch, and used the black as as feed from the switch, then you will have a short circuit between live and neutral

[ARWadworth]

You mean "traditionally"

For the old colours a red/black T&E would do with red sleeving on the black

It is not a dodged way of wiring a light if strip connector is used for the neutrals in the lightswich backbox and the earths are properly terminated (either at an earthing point if the backbox is metal or again in a piece of strip connector if the backbox is plastic).

Not OK on a looped system!

Adam

[Kevin]

twin and earth with 2 red cores? I have never seen it used , only normal twin and earth with the red being the live and black being switched live to the light

[Andrew Gabriel]

It did exist, but wasn't commonly used.

[Kevin]

my first reaction was twin and earth with 2 red cores are you joking but after googling I found

I changed my reply to "twin and earth with 2 red cores? I have seen it used"

[john]

so I changed my reply to "twin and earth with 2 red cores? I have seen it

This cable is used as a switch wire - saves marking the black with red tape or the now blue with brown tape or sleeving.

[RedWinged]

Having trouble keeping up, but should just clarify: both cables (one coming from outside the loft going into the switch box, the other going from the switch box to the light) have one black, one red and one green/yellow wire each. Blacks are connected with electrical tape, reds go into the switch, and the green/yellows are both hanging loose, one with very little sheathing.

[ARWadworth]

The reason it was not commonly used was two fold.

1) It was bloody expensive compared to red/black T&E and a 100m bag of red sleeving.

2) It saves on mistakes. A roll of 1.5T&E is a roll of 1.5T&E. If you then put a roll of 1.5T&E red/red in the van it may get used for Live Neutral Earth runs by mistake. BTDTBTT.

Adam

[ARWadworth]

In your set up then the two blacks at the light switch are both neutrals and should be connected together in a piece of strip connector and not twisted together with tape around the twist. The earths should also be connected together as per my earlier post.

There are many ways to wire a lighting circuit up. You cannot say one of these ways is "the correct" way do do it with all the other options being "wrong". In some cases you have to use a method that is most suitable for the job you are doing.

Adam

[Palindrome]

So you:

1) take the tape off the black wires and join them using an insulated chocolate block connector.

2) sleeve the earths where needed and join them using either a fixed screw-own block on the pattress (if one is present) or an insulated chocolate block connector (otherwise).

3) The red wires go into the switch, If you get a new switch that has three connection points and "the switch doesn't work", move one wire to a different connection point.

-- Sue

[Andrew Gabriel]

There was also single red and earth, which I came across a few times. I think there was a single sheathed black, but I never came across that.

I really wish electricians wouldn't bother put the sleeving on. I find it on the wrong wire often enough that it's much safer not to use it at all, and I certainly don't take any notice of it.

[ARWadworth]

There was a single red and earth that had a proper manufactured sleeved geeen/yellow PVC around the earth/CPC. It is very rare. It was usually done with a red outer PVC covering as well ie.a red pvc around the live and a green/yellow PVC around the earth with a red outer covering of both these PVCs. My research suggests it was only used in the early seventies.

The black singles are/were very common on some houses, as are blue singles on some new builds (with a grey/white outer PVC covering on top of the black/blue of course) unless it is for conduit use.

The lack of the red sleeving is a fail on a PIR. Personally I think it is a minor fail (code2) and just needs room for improvement.

Adam

[John]

Red to Red , Black to Black, Blew to bits!!

DO NOT follow the advice from Gazz

HTH

John

[PC]

A picture is worth a 1000 words

link:

[cj]

Hi In your case as stated connect the 2 blacks together in a 'choc block' connect the 2 earth cables to the brass lug on the back box and place 1 red in com and 1 in L1. You may need the earth if you have a flou' in the loft or a metal light fitting. As for wiring being wrong this is not so it is known as 2 Plait wiring and whilst phased out years ago is still used. The polarity issue is another matter if the wiring is correct the red wire will be Live with respect to earth and could kill whilst the black at most will tickle.(not recomended to touch either though) Twin red was common-place but now replaced by twin brown and single red+E and black were widely used to save money by many councils in the 70's. As for being to expensive ,see your suppliers you are being ripped off, 1.5 t&e costs the same as as 1.5 twin brown give or take a few pence per 100m ,they bump the price up because no-one asks for it. And yes I to have wired a lighting circuit only to find I used the wrong roll.(buy 50m rolls of twin brown now hehe) On a different tack ( IIM ) just come across a new light switch. For all my career can only remember 2way switches with comm at top (on its own) L1 & L2 below or similar (ie top switches to bottom right or left) These SOB's have L1 at top and com & L2 at bottom. Just goes to show Always read the label!!!

CJ

[RedWinged]

Cheers for this, and for everyone else's input - you've all been awesomely helpful!