wiring a two gang two way light switch Ask questions and find answers to many subjects relating to electrics and electrical work

[oastee]

I know this has been posted before but I am struggling with the wiring on a 2 way, 2 gang light switch and its driving me nuts! I want to replace the current 2 way switch and have the usual two power cables going into the switch- one with a black wire and a red wire, the other cable with three wires; yellow, blue and red. The switch powers the downstairs hall light and one on the upstairs landing. I have finally got both lights working ok when operated from the down stairs switch, but now the 1 way switch on the upstairs landing does not work. Can anyone help me please, I'm desperate and I've tried as many combinations as I can think of! The confusing thing for me is that the old switches have an L1, L2 and Common but the new ones have L1, L2 and L3 and its the L1 that seems to be marked off as the Comm. appreciate any help!

[ericmark]

[quote="oastee"]The confusing thing for me is that the old switches have an L1, L2 and Common but the new ones have L1, L2 and L3 and its the L1 that seems to be marked off as the Comm. appreciate any help![/quote] L1 = Com, L2 = L1 and L3 = L2. As long as you get Com (L1 on new switch) correct other two will not really matter if wrong way around.

[sparx]

Hi,
first some correct terminology for the benefit of all:
GANG = how many switches on the faceplate ie 2 Gang = 2 independant switches of any sort ie 1 WAY or2 WAY or Intermediate.
1 WAY = On/Off from single position
2 WAY = On/off from 2 positions
Intermediate = On/Off from 3 or more positions.

So You seem to have a 1 Gang-2 way switch at top and bottom of stairs.
Ignoring the markings the common on each switch will be alone at one end, with the other 2 terms together at the other end of each switch.
Pick a colour at the top switch (say yellow) as common, with red and blue in the others (either way around).
At bottom switch put yellow in common and both reds in one term. and blue/black in other term.
Job done!

[oastee]

Thanks a bundle to Sparx and Ericmark but just to clarify the situation I definitely have a 2 way, 2 gang light switch downstairs (hall) but a 1 way upstairs (landing). The Hall switch controls the Hall light and landing light; the landing switch ONLY controls the landing light. In a nutshell if I go upstairs and I've left the Hall light on I have to go back downstairs to switch it off! The double switch has two sets of L1-L3 connectors, 3 at the top of the switch and 3 at the bottom, with what appears to be a big SLASH across the switch which I am assuming is to denote the left hand and right hand switch connections. This is why I have been tearing my hair out as I've tried as many different wiring combinations as I can. As I said on the post, what I have now are the two lights working ok from the Hall switch but the landing switch only works independently i.e. if I turn on the landing light from the hallway I cannot turn it off from the landing switch. does that change your advice?!

[sparx]

hi oastee,

If downstairs light working ok then ignore that switch half, which as you say is denoted as seperate by the 'slash'.
Rereading your original post leaves me wondering about original circuit as it seems you only have one 3 core cable at the upstairs switch & one 3core and one twin cable at the bottom switch?
If so and the twin is working the hall light ok then the method of wiring the two-way is slightly different from my description.
Just confirm there were no red link wires between the original double switch downstairs please as this will make a huge difference to the wiring.
This wiring is so easy to sort out 'hands-on' max 15 mins for a leckie but so many possibilities to try on here

[Freddy12]

Hi
I think Sparx is assuming you do not want the hall and landing lights to be switched independently, as from his description, they will both be on or off together. The only way to control them independently is to have a 2 gang, 2 way switch at both locations. You will therefore need extra wiring between the upstairs switch and the hall light.

Freddy

[oastee]

Thanks Freddy but I'm trying to keep it simple, not make it more complicated! All I want to do is replace an old, battered 2 gang, 2 way light switch with a shiny new one! Its a like for like swap but like a numpty I assumed the manufacturers instructions that came with the new switch would be the correct setting for the switch (and they're not). I should have taken a picture of the old one so I could just copy the set up but I didn't, so now I'm trying to find out the correct setting so I can carry on as before with the lights! All I need to know is the combination for the 2 way and I'm home and dry.....

[ericmark]

The double switch has two sets of L1-L3 connectors, 3 at the top of the switch and 3 at the bottom, with what appears to be a big SLASH across the switch which I am assuming is to denote the left hand and right hand switch connections.

Yes the SLASH does denote the left hand and right hand switch connections.
So taking each switch on it's own.
1) On/Off switch will use L1 and either L2 or L3 swapping L2 and L3 will swap which way is on and which way is off so either L2 or L3 will be empty.
2) The two way switch will have a three core cable and the same colour needs to go to Com or L1 if there is no Com. If the other two are wrong way around switch will swap as to being both up or down for off or on up and one down for off. The two core cable will go to L2 and L3 or if the switch marked with com then L1 and L2.

So the switch wires from lamp with on/off go com(L1 if no com) and L1(L2 if no com) i.e. does NOT use highest number. But with two way it's the Com or lowest number that the switch wires do NOT use.

[oastee]

Boys, thanks to all of you for your suggestions and advice. I admitted total defeat yesterday and got a lad round to sort it so I'm back to normal lights again :0) appreciate all your suggestions though, thanks a million

[andyguest13]

Hi All,

I have this exact same problem too. Two-way two gang in hall, which controls hall and landing lights. One way one-gang on landing to control just the landing. The way it is wired is wrong as sometimes i have to go downstairs to switch the landing light off.

Here's what wires there are, i would like to know what they are and how to wire the switches up properly - it surely is a common scenario:

Downstairs (Hall): There are two cables coming out the wall; one is two-core (Black and Red) and the other is three core (Yellow, Blue, Red). These 5 wires have 6 possible holes they could go in the back of the switch.

Upstairs (Landing): Same wires here! two core black/red and 3core (Yellow,Blue,Red) But the 5 wires of course have only three holes to go in the back of the single switch.

thanks
andy

[sparx]

Hi,
start downstairs:
Find layout of switches ie com +l1&l2 for each half of plate, normally Com is opposite its L1,L2 connections
put black into one of the L1 terms and the red from the same 2core into opposite Com.
with all other wires safely out of the switch and into choc-bloc for safety, turn power on and check hall light works, if not use the other Com.
Once thats ok, with power off of course, put yellow into other Com. term. Red in L1, Blue in L2.

Upstairs put yellow into Com.
Both reds in L1
Blue & black into L2
switch power on and have a congratulatory G&T.

[andyguest13]

Hi,

Thanks - i'll try that when I get home and let you know.

Andy
ps, Terminal -- I knew there was a technical term for 'hole' !

[andyguest13]

Hi,
Just to let you know that this worked ! Thanks very much indeed.
Andy
ps I did have to swap the hall COM

[thedoctor]

Guys, there's a huge amount of electrical information in our project pages of the main website and also further information on gang switches can be found in our How to choose the right type of switch and understanding the difference between 1 and 2 gang switches

[ericmark]

13th Feb 2012 to 5 July 2013 is quite a long time. It does however point out admin failures the comments by me were to have been removed after I was banned. Clearly this one was missed.

One does need to be careful with old posts as regulations have moved on. Really all electrical posts before April this year need deleting as they may contain wrong advice with the changes in Part P.