Confusion over wiring after re-plastering

[EggMella]

Hi,

I have what is going to be a simple problem for you guys but it's something that has me completely stumped.

My hallway and landing was recently re-plastered and the plaster removed all the sockets & switches, this is fine and it looks great except I have no idea how to get them working again. Upstairs appears to be the easiest to tackle first so I'm looking for any advice you can give me.

It's a 2 gang, 2-way switch. There are 3 electrical cables feeding in to this, 2 of them are 4 core and 1 which probably goes to the landing light is 3 core.

The 3 core appears consists of the following
1 live (brown) = this is confirmed as a live AC wire, it is wired through a connection block to the "4 core (feed 1)" brown wire below.
1 neutral
1 Earth

4 core (feed 1) goes downstairs it is wired directly into the live from the ceiling rose as above:
1 brown wired directly to the live wire
1 grey (common?) switching wire
1 black switch wire
1 Earth

4 core (feed 2) going downstairs this currently has a live of its own:
1 live (brown) confirmed live AC
1 grey (common?) switching wire
1 black switch wire
1 Earth

Am I right in thinking that the 4 core "feed 1" and 3 core work together with the downstairs switch to turn on and off my landing light? If so I'm confused by the fact that the live is wired directly in to 4 core wire but my intelligence aside. I have L, L1 and L2 on the upstairs and downstairs switch how do I wire these together to actually shed some light on the situation? (sorry)

Not sure if this is relevant but downstairs there are 5 feeds into the switch, amongst these is a neutral wire & black wire (with blue tape around it) wired together into a connection block. There are also another 2 cables with their browns wired together into a connection block. I'm assuming these are unrelated to the landing lights as there are many more circuits going into the downstairs lights.

 

[PrenticeBoyofDerry]

Have checked this out?
//www.diynot.com/wiki/electrics:lighting

 

[ericmark]

The diagrams are best way and there are plenty. L and L1 + L2 will likely mean L is common with one way switching one of the switch wires will always go to com (L) with two way switch the pair from lamp do not go to com (L) and the three core (not counting earth) will have same colour to same terminal each end.

So with two way switches one of the pair will have two wires in L1 and L2 and single wire in L (Com) other switch of pair will have same colours to each terminal.

Shows basic wiring for lights.

 

[sparkwright]

Hi,

I have what is going to be a simple problem for you guys but it's something that has me completely stumped.

My hallway and landing was recently re-plastered and the plaster removed all the sockets & switches, this is fine and it looks great except I have no idea how to get them working again. Upstairs appears to be the easiest to tackle first so I'm looking for any advice you can give me.

It's a 2 gang, 2-way switch. There are 3 electrical cables feeding in to this, 2 of them are 4 core and 1 which probably goes to the landing light is 3 core.

The 3 core appears consists of the following
1 live (brown) = this is confirmed as a live AC wire, it is wired through a connection block to the "4 core (feed 1)" brown wire below.
1 neutral
1 Earth

4 core (feed 1) goes downstairs it is wired directly into the live from the ceiling rose as above:
1 brown wired directly to the live wire
1 grey (common?) switching wire
1 black switch wire
1 Earth

4 core (feed 2) going downstairs this currently has a live of its own:
1 live (brown) confirmed live AC
1 grey (common?) switching wire
1 black switch wire
1 Earth

Am I right in thinking that the 4 core "feed 1" and 3 core work together with the downstairs switch to turn on and off my landing light? If so I'm confused by the fact that the live is wired directly in to 4 core wire but my intelligence aside. I have L, L1 and L2 on the upstairs and downstairs switch how do I wire these together to actually shed some light on the situation? (sorry)

Not sure if this is relevant but downstairs there are 5 feeds into the switch, amongst these is a neutral wire & black wire (with blue tape around it) wired together into a connection block. There are also another 2 cables with their browns wired together into a connection block. I'm assuming these are unrelated to the landing lights as there are many more circuits going into the downstairs lights.

You seem certain grey should be in the common.

This wire you call neutral in the 2 gang switch probably isn't.
If it goes to one terminal of it's own at the rose, along with the live of the light, it will be 'switch live' - not neutral.

Any brown sleeving on this blue?

Sometimes blue is used as live, and is sleeved with brown sleeving to show it's live and not neutral.

Once you can verify all of the above, at this upstairs 2 gang switch I would suggest;

2 core and earth cable...
brown in L1 of switch A
blue in L2 of switch A

3 core and earth cable 1...
brown in L1 of switch A
black in L2 of switch A
grey in Common of switch A

3 core and earth cable 2...
brown in L1 of switch B
black in L2 of switch B
grey in Common of switch B

Join all earth cables to back box earth terminal if there is one, failing that in a piece of connector block. If the switch plate is metal this MUST be connected to earth. Any bare earth wires must be covered with green and yellow sleeving.

The same colour wire should be used in the common terminals of both switches, up and down, - so hopefully you are correct about grey being used as common.

 

[sparkwright]

And why is your plasterer removing switches, he needs smacking in the mouth.

 

[ban-all-sheds]

That's a bit harsh?

If he's turned up to do some work and EggMella hasn't removed the switches, what's he supposed to do?

 

[sparkwright]

He didn't put them back though, did he?

 

[Steve]

If he's turned up to do some work and EggMella hasn't removed the switches, what's he supposed to do?

Plaster around them

Seriously though, my plasterer loosened them off. He's still alive.

 

[sparkwright]

Re; Eggmella's plasterer.
He's probably one of them know-all plasterers who can't plaster round a first-fix cable dangling out of a ceiling; and has to shove it up in the void and leave it.

Or he's the type who, when tacking a ceiling, sees some cables clipped to the very edge of a joist, then boards over it, causing a bulge in the plasterboard. Then leave it.

Or he's the type who plasters round metal boxes, fills up the boxes, then may decide to clean them out later with a claw hammer leaving a jagged edge and bent fixing lugs. Then leave it.

Young chap, was he?

 

[1john]

Re; Eggmella's plasterer.
He's probably one of them know-all plasterers who can't plaster round a first-fix cable dangling out of a ceiling; and has to shove it up in the void and leave it.

Or he's the type who, when tacking a ceiling, sees some cables clipped to the very edge of a joist, then boards over it, causing a bulge in the plasterboard. Then leave it.

Or he's the type who plasters round metal boxes, fills up the boxes, then may decide to clean them out later with a claw hammer leaving a jagged edge and bent fixing lugs. Then leave it.

Young chap, was he?

have you had your boxes completely dabbed over with plasterboard too, and boxes completly filled with skim so they cant be seen??

 

[EggMella]

Thanks for the detailed response answers below....

You seem certain grey should be in the common.

I'm guessing to be honest.

This wire you call neutral in the 2 gang switch probably isn't.
If it goes to one terminal of it's own at the rose, along with the live of the light, it will be 'switch live' - not neutral.

Any brown sleeving on this blue?

Sometimes blue is used as live, and is sleeved with brown sleeving to show it's live and not neutral.

Yes spot on about the brown sleeving, actually all the wires in this box appear to have brown sleeving on them (barr the Earth's). So it is a switching live. I've looked in the rose which has a lot of brown and blue wires in it so not sure whether the blue I'm looking at goes directly to the rose or not.

Once you can verify all of the above, at this upstairs 2 gang switch I would suggest;

2 core and earth cable...
brown in L1 of switch A
blue in L2 of switch A

This is where I get confused the problem is that the brown wire goes to a connection block where it is connected to the brown wire from the 3 Core & Earth that travels downstairs. There isn't anything hanging off it to connect it to the switch itself. There are 3 wires available in the box (actually there are 6 in total including the 2nd 3 core) so I was thinking 3 of these attached to the upstairs switch (L, L1 and L2) and the other 3 attached to the switch controlling the downstairs lights (L, L1 & L2).

So, of the 3 wires that I'm guessing belong to the upstairs circuit 2 of them come from the 3 core and Earth from downstairs and the other is the blue switching live from the pendant.

3 core and earth cable 1...
brown in L1 of switch A
black in L2 of switch A
grey in Common of switch A

3 core and earth cable 2...
brown in L1 of switch B
black in L2 of switch B
grey in Common of switch B

I was thinking that 1st 3 core cable goes downstairs to allow the downstairs 2 gang to control the landing lights. Whereas the 2nd 3 core cable came from downstairs and allows the upstairs 2 gang to control the downstairs lights. FYI: The upstairs & downstairs lights are on separate circuits.

Join all earth cables to back box earth terminal if there is one, failing that in a piece of connector block. If the switch plate is metal this MUST be connected to earth. Any bare earth wires must be covered with green and yellow sleeving.

The same colour wire should be used in the common terminals of both switches, up and down, - so hopefully you are correct about grey being used as common.

The switch plate is connected to the Earths, the back box isn't and doesn't appear to have a ground. If I manage to get to a point where I'm worrying about this bit I owe you a beer

 

[sparkwright]

The connector blocks you mention - would these have been fitted originally, or have these been put on later? Perhaps your plasterer fitted them in some attempt to blank live ends off?

Are you fitting new switches this time? Were the old switches push-in time-lag switches (may account for some wires just terminated in blocks)?

Plastic back boxes often do not have an earth terminal, and do not directly require earthing.

Old metal back boxes from before about 1970 may not have earth terminals.

Any untouched, related switches in the vicinity you could look at to give you idea of which colour has been used for common?

As pointed out, wires with brown sleeve should show they are live, rather than neutral. Be aware some sleeving may have dropped off during the work.

PICTURES most welcome.

 

[sparkwright]

We like pictures.

 

[ban-all-sheds]

not sure whether the blue I'm looking at goes directly to the rose or not.

Which is why, if you want to do work on your electrics, a multimeter is just as necessary as screwdrivers, wire cutters and strippers etc.