Double switch not turning off

[whydidistartthis]

Hi again guys, you've been great getting me through my switch issue that I put here

Thread 'Frustrating light switch swap'

3 May 2026

Im at my whits end and I wonder if anyone can shine some light on this for me before I fully admit defeat.

Here's what I've Got at the moment

1 x upstairs 2 gang, 2 way switch which controls the landing light (controlled at the bottom of the stairs with another switch) and bathroom light.

I'm wanting to swap this for a switch (for the landing light) and a dimmer for the bathroom spots (don't ask why the misses was moaning it was too bright and didn't take my suggestion to wear sunglasses very well)

Having taken the switch off I have the following on the old switch:

2 x twin and earth...

• whydidistartthis
• Replies: 11
• Forum: Electrics UK

I've wired the switches in and have a downstairs and landing switch working, plus a bathroom switch that feed a dimmer....all working


One issue i can't seem to fathom, if I turn the downstairs switch for the landing light on I can't use the upstairs switch to turn it off and vice versa....the upstairs one can't be turned off by the downstairs.....I havent touched anything in the downstairs switch at all, the landing switch I have just swapped to a new 1 gang 2 way...any ideas what this might be?

The old switch is this

And I've connected it to the new switch like this

L3 old switch to COM on new,
L2 old switch L2 new
L1 old to L1 new

The L1, L2 on the furthest left are to the bathroom light and all working fine so I'm guessing the issue is the 3 above somehow

 

[ericmark]

L1 new = Com old. If the L2 and L3 are the wrong way around it does not really matter, but Com must be correct.

Only one wire connects to com. And com will be same wire on both switches.

 

[terryplumb]

L1 on your old switch= com on the new.

 

[whydidistartthis]

So would that mean that it's as follows on the new switch

COM - L1 old
L1 - Com old
L2 - L2 old

?

 

[terryplumb]

No.
Old switch L2 and L3
= L1 and L2 on the new.

 

[whydidistartthis]

Thanks guys you've done it again much appreciated