Query on replacing a light switch please.

[dann07]

Hello
I have redecorated and am trying to replace an old Light switch.
It is older Blk and red wiring.

This is the way it works.

At the bottom of the stairs i have a double 2 way switch which operates both upstairs and down.
At the top i have a Single switch which only operates the upstairs light.
I have replaced the double switch downstairs, no problem.
But when i took off the old switch upstairs, i noted the way the wiring was and tried to fit a new switch.
The old permutation from the old switch didn't seem to make the new switch work so i tried switching around until i got the light working fine.
The only trouble i have is when the downstairs lightswitch turns on the upstairs light, the upstairs lightswitch won't turn it off.

I have one Red and Two Blacks wires in the upstairs switch and i have both a single 1 way and a single 2way switch i can use.

Which should i use and can you please tell me the way round the wiring should go.

Many thanks.

 

[bongos]

More questions - sorry!

Have a look here for more info.

Have you definately connected the wires the same as they were at the downstairs lightswitch?

What colour core do you have at C/L1/L2 on the downstairs switch? This will often be the same at the upstairs one but will depend how the lighting has been wired...

And you'll need a two way switch, not one way.

 

[dann07]

on the downstairs switch i have:
Red wires to the Commons and Blacks to the L1's.
There is also a wire crossing from one common to the other (forming a bridge if you like).
This is how the old one was wired, al least i think it was

maybe this switch is the trouble ?

Thanks

 

[mikeyd]

You need a wire in all 3 terminals for 2 way switching to work.

Probably one of the reds went to COM on both switches (via the link) and the other red wire was in L2.

 

[dann07]

Really silly question now.
Is this how i should wire both switches:

2Way - Blks to L1
one red to L2
one red to common the link to other common

1Way upstairs - red to common and Blks to L1 & L2

i think i'm confusing myself by swopping so much.
i've wired up 1 and 2 way switches already in the house but this is getting to me lol

Cheers

 

[ban-all-sheds]

This is how the old one was wired, al least i think it was

Ahhh...

maybe this switch is the trouble ?

Quite possibly.

There would be no point in having a conductor to each COM and having link between them.

I suspect you may have had this downstairs:

Switch cable for downstairs light to one side, Live in COM and return in L1.

Link to COM on the other side with the other cable to L1 & L2.

Upstairs:

Cable from downstairs switch to L1 & L2

Switched live for landing light from COM.

So the 2-way side looks like the top left part of the first diagram here: //www.diynot.com/wiki/electrics:two-way-lighting

 

[mikeyd]

I would try that yes. Obviously you don't know which red is which now so you might have to try twice.

By the way, the switches are 1 gang and 2 gang, not 1 way/2 way (they are both 2 way)

The very first picture in the wiki (click here) is how I think it sounds like it is wired.

 

[dann07]

Thanks BAN-ALL-SHEDS.

It certainly was the downstairs switch. Got the strappers wrong.

Top Man