Wiring a cooker/ plug socket.

How easy is it to check behind the cooker, to see if it's red/black or blue/brown wires in the outlet there?

Obviously make certain the cooker circuit, or the whole of your fuse box is turned off first.

Not very, but I could try. Its all right down at the back on the floor basically and I am not sure the colours are showing.

Presumably as well as L and N markings, there are also "load" and "supply" markings?

As long as you DON'T put a red or a brown into a neutral hole, and don't put a blue or black into a live hole, nothing will go bang or anything.

But if you get them wrong, you'll have the odd situation where the fridge will be off if either of the switches is off.

I'd leave it until it's daylight again ...

Likely black and red are the wall (input) side, blue and brown are the cooker (output) side, as the wall wiring was probably installed pre-2005 (old colours) and the cooker point post-2005 (new colours).

The switch probably has markings for which is in and which is out. On a normal switch it wouldn't matter, but if you get input and output mixed up the neon will light even when the switch is off. Any earth wire will go in any earth hole - the bundle in one, the single in the other.

If you manage to short black and red or blue and brown then something may go bang and (hopefully) trip the circuit breaker. As long as you keep live to live and neutral to neutral then you should be ok. I think worst case is you get some strange neon behaviour.

Make sure the screws are done up tight, and give a sharp tug on each wire to check they're not going to come out. A common source of house fires is electrical terminals which aren't properly tightened and so overheat. (The proper way to do this is with a torque screwdriver and tighten the screws to a rated torque in Nm, if the switch manufacturer have specified one)

Good luck!

Theo

You will likely have two cables - one is the feed from the CU, and the other will be the cable to the cooker itself. Each cable will have an earth, and there may be a flying earth wire that goes to the back box of the socket.

One pair of L & N will be the Supply side, and the other the load side (the connection from supply to socket will be internal to the unit and won't need another cable)

Look carefully at the back of the new socket and it will be marked which terminals are which. (lower ones are likely to be the load side)

At a guess - assuming the house wiring predates the use of Brown/Blue for fixed wiring, the read black cable will be the supply. The Brown/Blue is probably the age of the cooker itself - so more recent.

With the circuit off at the CU, you can use a multimeter to measure the resistance between the Earth and Neutral wires. On the wire to the cooker (i.e. the "load") there should be an open circuit. On the supply side there would usually be a low resistance since the neutral and earth will be linked somewhere (either at your house or at the sub station depending on the type of earthing system your property has)

Nothing serious - it will work, and the switch will turn the cooker on and off. However, with the cooker "off" the socket may not work either. Also, the neon indicators would be probably stay lit all the time. (they will be connected to the load side of the switch - normally only powered with the switch on)

Thank you for the replies. I cannot see the cooker wires because apparently they were joined in a junction box somewhere behind a kitchen cupboard.

But what I can see :

There are two conduits coming out of the wall - one coming down the wall into the top of the metal casing and the other going down the wall to where ever from the bottom of the casing

On the going down side is the black wire, the red wire and one of the green and yellow wires that is joined to the other green and yellow wire The green and yellow wire it is joined to is coming down through a tube/conduit(?) from the ceiling The other green and yellow wire, seems to be going nowhere except into the edge of the metal case .... presumably its fitted in the back ( The casing is fixed in the wall. Its only the socket front I am changing.

The blue wire and the brown wires are coming down in the conduit from the ceiling.

If its any use - the consumer box and electricity boxes are all on the wall below the ceiling . The wiring to the house comes in on overhead wires ( old fashioned I know) into the roof

Hope that makes some sense.

I cannot see anything that says load and supply. The socket box has four holes on top of a square shaped ( pre wired) black box thing - two on the top marked earth and neutral and two at the bottom marked earth and neutral. The E earth wires are both on the side next at the back of what is the plug socket ( on the front) Both are to the top of the unit.

Too late now but a mobile phone photo of what you are going to take apart helps a lot when replacing things like this.

Is this a single switch or is a a cooker switch with a 13A mains socket in the same assembly.

If it's a MK socket it will have come with an instruction leaflet. That leaflet will probably have a picture of the back of the socket showing "supply" and "load".

"Supply" may be named "Mains" "Load" may be named "Cooker"

The back of many MK sockets is shown in

Can you supply a photo of the back-box with the wires and a photo of the replacement socket?

Red and black are the old colours Red = live Black = neutral

Brown and Blue are the new colours (introduced in the 1990s ?) Brown = live Blue = neutral

One set will come from your consumer unit (fuse box) The other set will go to your cooker

The problem you have is identifying which is which :(

Each of those sets of wires will have an earth wire (usually sleeved with a green or green and yellow sleeve) The third earth wire is probably just connected to a connection on the metal back-box. All three should be connected any of the terminals marked E on the back of the socket. All three don't have to go to the same "E" terminal if the socket has more than one marked this way.

There should be 5 or 6 connections: 2 Live (one in, one out), 2 Neutral (one in, one out) and one or two Earth.

It sounds like your Brown/Blue wire is the supply, dropping down to the switch and the Red/Black wire is feeding power from the switch to the cooker.

Live in should be marked L, L1, Lin or something like that and take the Brown wire. If it is only marked L, there will also be Supply, Mains or Incoming marked somewhere.

Neutral in should be marked N, N1, Nin or something like that and take the Blue wire. If it is only marked N, there will also be Supply, Mains or Incoming marked somewhere.

Live out (to the cooker) should be marked L, L2, Lout or something like that and take the Red wire. If it is only marked L, there will also be Cooker, Load or Outgoing marked somewhere.

Neutral out should be marked N, N2, Nout or something like that and take the Black wire. If it is only marked N, there will also be Cooker, Load or Outgoing marked somewhere.

The green and yellow wires all go to the Earth connections (which are already connected together if there are more than one.

At the worst, if you get the incoming and outgoing cables swapped over, the Neon will stay lit and the socket will lose power when the cooker switch is off, so just swap them over. DO NOT get the Brown and Blue swapped over or the Red and Black.

The brown (live) and blue (neutral) are the probably the supply (or mains)

The red (live) and black (neutral) are probably your cooker (or load)

The back of the socket will be marked with L supply (or L mains) = Brown wire N supply (or N mains) = Blue wire

L load (or L cooker) = Red wire N load (or N cooker) = Black wire

All three earth wires should be connected to Earth terminal on the switch. You are correct that the 3rd earth wire is just connected to a metal back-box (for safety).

As posted elsewhere in this thread see the diagrams of the back of various MK cooker switches in

I think the new colors go back further than that. i installed new colors in 2001 and had been doing so for some years

It was all EU harmonisations. It finally became absolutely mandatory in

Well, the good news is I have it working :-) I got up this morning and six am whilst husband was asleep and did it. I had just finished when he caught me.

The bad news is my husband is livid with me. :-( he now feels I have shown him up. I said " Happy Birthday, I have done it for you" ( Its his birthday today). Now I can make him a birthday cake.

Now , whether I have it right or not is another question. I had to fight to get the wires into the terminals. I had to fight to push it all back to the casing and put the screws in . But I got it there and I switched on - no bangs and neon lights lit up when cooker switch came on and cooker works. Same for the socket.

So, thank you all very much for your help. You have been a God send. ( Hubby hasnt been well and is struggling. I guess he feels I no longer need him when I can get it done myself).

Thank you all very, very much for your promptness and clarity ( and the pdf of wiring instructions.)

That's normal as the wire to your cooker is thicker than used for the ring main to your other household sockets. The wire is a lot harder to bend etc. to get it back into the back-box in the free space available.

I bought a reel of 2.5 T&E in 1970 and asked why it was still red and black when domestic flexes had changed colours. I think the change was quite recent then. I believe any portable wiring since 1976 must be in the new colours.

So it's very likely that the cooker wiring was brown/blue and the house wiring red/black.

Well in Spain white and black still in use. I don't usually support conspiracy theories but I thought it was for Part-P so any new wiring was obvious...

Dave

That was probably convenient, though I'm sure I'm not the only one to have a few bits of red and black left...

The portable wiring colours changed in the late Sixties, for some reason it took fixed wiring about forty years to catch up. The European Cenelec is associated with the change, which took place before Britain joined the EU.

You could use new colours before part p, and old colour after it (the crossover period straddled the introduction).

So as conspiracy theories go, it is debunked before it even starts!

Although the colour change came in shortly before (March 2004) Part-P (Jan 2005), so isn't an immediate identifier of when work was done.

You (or your husband) need to get someone qualified to look at it, on the spot. That's as helpful as I care to be in such circumstances.