I know this has been posted many times before but I can't find my particular problems' solution, so sorry but I need help. I am trying to replace my double light switch in the hallway that operates the hall light and also the upstairs landing light, the switch in the hall is 2 way, the landing is 1 way. After mucking around for hours I have the 2 way switch wired up so that the downstairs and upstairs lights work from the hallway, but now the switch on the landing upstairs doesn't switch the landing light off! the wires for the downstairs are the usual, 1 red and 1 black from one cable, then 1 red, blue and yellow from the other cable. The upstairs landing has the same number and colour of wires plus an extra earth.
The thing that is most confusing is that the new 2 way switch shows L1 as being the Comm too, but the upstairs landing is wired with the red & black to L2, the red and blue to L1 and the yellow to Common, it doesn't have an L3??!! Help anyone before I go mad please :0)
Some switches label the common as Com others as L1. There are a number of ways to wire a two way system the most common way is to take the two switch wires to the two non common terminals (L2 + L3 or if marked com then L1 + L2) then the two switches are connected together like for like.
Using a two way switch as on/off then the two switch wires go to com (L1 if no com marked) and any one of the other two terminals.
Pictures not allowed on this site so maybe better to find one which allows pictures.
Two way is NOT wired as shown as a school boy. The problem with school boy method is you need to put a connector block somewhere. There is an exception where the cables are taken to ceiling rose but this is rare.
The fact that the switch wires from lamp do not go to com with two way but do with single way can confuse the apprentice. But remember between switches normally red, yellow and blue it goes like to like so if red is com on one switch it is also com on other switch. Really only the com has to be right swap other two and it will still work.
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