Swapping a dimmer out for a standard switch

[vengenerator]

Hi there,
I had a 2 switch dimmer in my hallway. One dimmer controlled downstairs hall lights and other dimmer controlled upstairs landing lights which could also be switched upstairs. I've just tried to swap the dimmer out for a standard switch.

The dimmer had 3 terminals L1, L2 and a arrow with a wavy line. My new switch also has 3 terminal labelled L1, L2 L3. I rather naively thought arrow and wavy line must be L3 so copy the wiring and all should be well...

The downstairs lights work fine but the upstairs lights are not working correctly after the switchover.

The dimmer that controlled upstairs was connected as L1 black, L2 grey, arrow brown.


I've tried the following for the upstairs lights:
L1 L2 L3
1) black grey brown - switch didn't do anything (didn't try upstairs switch).
2) grey black brown - downstairs switch works but upstairs does nothing
3) grey brown black - downstairs switch works but upstairs does nothing
4) black brown grey - downstairs works only if upstairs is in on position.

Now I'm rather confused and not to thrilled with my trial and error approach. Any advice would be very much appreciated at this moment with socket hanging out of the wall!

VenG

 

[sparkwright]

First of all, do you remember how the old switch was connected exactly?

It may well be that
arrow = L1
L1 = L2
L2 = L3

 

[sparkwright]

For upstairs only, it sounds like you need the brown in L1.

The black in L2 and the grey in L3. These can be reversed if you like.

Does the downstairs switch seem to work upside down? If so, check you have used only L1 and L2, wires either way round.

I take it this new 2 gang switch is a Crabtree.

 

[vengenerator]

Many thanks!

Yes that works perfectly,
L1 brown, L2 black, L3 grey has done the job. Upstairs lights working perfectly.

The downstairs one seems to work OK as was but this was only using 2 terminals, L1 and L2 on the dimmer and I'm using the same in the new switch.

Yes it is a crabtree socket. Nice to look at but a pain in the a** to get the faceplates to clip on properly.

 

[PrenticeBoyofDerry]

If you have only changed the two downstairs dimmers, how is the existing switch wired upstairs?

I would would normally have black in L1/com brown L2 and grey L3, but without knowing how the second way is terminated it is purely guesswork!

A little late with reply seems to be working now, but as I have said investigating the upstairs switch arrangement, would have hopefully prevented the trail & error/guessing approach.
Also hand y to remember/take note of existing connection prior to swaps and have an approved test instrument handy to avoid confusion/frustration!

 

[sparkwright]

Don't forget, if the new switches are metal they require earthing. You MUST earth them to the earth terminal provided.