Help! - rewiring a switch that used to work 2 lights

[calandra]

We have a double light switch in the downstairs hall that is supposed to control (1) hall light (there is another switch that also controls this) and downstairs loo light. We had some (but not all) wiring replaced in our house recently and this switch is pretty old. Up to yesterday, the loo light worked, but the second switch didn't do anything.

We removed the switch plate yesterday while doing some decorating, intending to possibly fit a new double switch. There were lots more wires than I was expecting and 5 different colours (green & yellow, red, black, blue, yellow).

There were 2 wires (red and black) hanging down in the box, the red was attached to one of the terminals and the black wasn't attached to anything.

There were also two cables coming up from the bottom of the box with 3-4 wires each. The two cables had green/yellow earthwires attached to the back of the box.
In addition to the earth wire, the first cable had (I think) a blue and a yellow in one terminal and a red and a black in another, and similarly, the second cable had a at least two wires in one terminal. I guess I need to take a photo because I can't exactly remember.

The bottom line is, except for the black wire hanging down from the top, everythign else was attached.

Although I ended up doing nothing other than making sure the wires were all tightly in their terminals, at the end, the loo light now doesn't work, and the hall light now does!

I thought about putting the black wire in to the empty terminal, but decided I didn't want to blow the whole house up, or something. Ideally, I'd like to put the new switch on. The new double switch has two terminals on the top, and four underneath, so I assume I'll need to do this doubling up of two wires in one terminal. But given the extra black wire, etc., I obviously need advice first.

Can you help (and/or should I try to post a photo?)

Thanks.

 

[ban-all-sheds]

the black wasn't attached to anything.

the second switch didn't do anything.

Probably not coincidences

We removed the switch plate yesterday while doing some decorating, intending to possibly fit a new double switch. There were lots more wires than I was expecting and 5 different colours (green & yellow, red, black, blue, yellow).

That may be more than you were expecting, but it's not more than would be expected by anybody who knows how 2-way light switches are wired..

There were 2 wires (red and black) hanging down in the box, the red was attached to one of the terminals and the black wasn't attached to anything.

There were also two cables coming up from the bottom of the box with 3-4 wires each. The two cables had green/yellow earthwires attached to the back of the box.
In addition to the earth wire, the first cable had (I think) a blue and a yellow in one terminal and a red and a black in another, and similarly, the second cable had a at least two wires in one terminal. I guess I need to take a photo because I can't exactly remember.

A photo now is probably going to be of little use.

Before you removed the switch, did you make a note of which conductors went where?

Although I ended up doing nothing other than making sure the wires were all tightly in their terminals

We removed the switch plate yesterday

The new double switch has two terminals on the top, and four underneath,

Surely your old switch also has 6 terminals?

How are they all labelled, in the old & new switches?

I obviously need advice first.

http://www.diynot.com/wiki/electrics:lighting

 

[calandra]

I didn't actually remove the old switch, just put it back. So a photo might help.

The old switch might have 6 terminals, I'll have to check. The thing that threw me was the 2 wires in each of two terminals - nothing simple like the diagram provided with the new Homebase switch.

 

[ban-all-sheds]

With 2-way lighting there will nearly always be more than one wire per terminal at one end. What were Homebase trying to tell you?

Read the Wiki article and all will become clear...

 

[calandra]

Ok, am I interpreting the Wiki diagram correctly:

Both the cables from the bottom of the box (in my case) go to the hall-light (operated from 2 locations - the 2-way light). One is the circuit cable and one is the linking cable.

So if that is right, then the red and the black cables hanging from the top of the box (the black cable is not plugged into anything) operate the bathroom light. Hence, if the black cable were hooked up correctly, perhaps it would work???

So for the single bathroom light, which terminal should the black wire go in (can't recall any of them being labled- by maybe they are).

(Should I be concerned that there is no green (earth) cable coming from the bathroom light?)

If I can figure out how to get the bathroom light working with the old switch, then changing everything over (as is) to the new switch should be doable.

Thanks.

 

[ban-all-sheds]

So if that is right, then the red and the black cables hanging from the top of the box (the black cable is not plugged into anything) operate the bathroom light. Hence, if the black cable were hooked up correctly, perhaps it would work???

Almost certainly - give it a try.

So for the single bathroom light, which terminal should the black wire go in (can't recall any of them being labled- by maybe they are).

Into COM and L1 - doesn't matter which is red or black.

(Should I be concerned that there is no green (earth) cable coming from the bathroom light?)

Yes. Has it just been cut back, or does the cable not have an earth core?

Is there an earth at the bathroom light itself?

We had some (but not all) wiring replaced in our house recently.

Which parts?

Why not all?

Who did it?

What testing did they do before starting, and after finishing, and what sort of certificate did they give you?