2 gang and 1 gang switch change help

ajmayers · Sep 18, 2019

Hi

In our hall we have an old 2 gang switch which controls the downstairs and upstairs lights.

There is also a 2nd 1 gang switch upstairs which just controls the upstairs light.

I am struggling to figure the wiring on the new switches, can anyone help which wire goes where on the new switches?

Pictures of both the old and new upstairs and downstairs switches attached.

Many thanks

[ElectriciansForums.net] 2 gang and 1 gang switch change help

Downstairs Old Switch

Downstairs New Switch

Upstairs Old Switch

Upstairs New Switch

Deleted account · Sep 18, 2019

I have to admit I’ve never seen light switches with the L1 and L2 in those locations before,

I would presume but check with testing before proceeding that the termination labelled L is the common.

Do not wire these up on my assumption. Either await another response to confirm this or get them tested or check the installation instruction that it should have come with.

telectrix · Sep 18, 2019

looking at those pics, it would appear that you have what is called a shared L or borrowed N. this is when the landing light has it's L from the downstairs circuit and N from the upstairs circuit. this can be dangerous and is not allowed for past 40+ years. please consult an electrician.

littlespark · Sep 18, 2019

Sorry, Tel, where are you seeing that? How can you tell there's 2 circuits involved?
I just see blacks being used as switchwires or strappers without any identification.

I agree with @Paignton pete that the new switch needs tested with a multimeter or something to know for sure which terminal would be the common

telectrix · Sep 18, 2019

the link between the 2 gang switches downstairs shows that L to landing is from downstairs. the common terminal upstairs has single sheathed cable to landing light. ergo L from 1 circuit. N from another. (unless of course, it's all 1 circuit anyway)

ajmayers · Sep 18, 2019

Thanks for everyone's responses so far - i appreciate it - i may get an electrician in to be safe if nobody has a definite answer...
If it helps this is the diagram from the switches - but I do not think is very helpful

I have a 1x 1 gang for upstairs and a 1x 2 gang switch for downstairs

Gawain · Sep 19, 2019

Don't know if you've sorted it or not, but looking at those pics, it looks pretty simple (unless testing proves otherwise) then in the 2 gang switch you put the two red cables you have labeled as common into the 'L', the t&e of red and black (upstairs) into 'L1' and 'L2' (strappers) and the remaining black into 'L1' downstairs.
The upstairs one, you put the red and black into the same 'L1 and L2' as the downstairs switch. If you put red into 'L1' then do the same. The grey single you labeled as common is actually the switch live and that goes into the 'L'
Hope this makes sense.