2 way gang 2 way switch problems

[tigershaun]

i have wired a 2 way gang 2 way switch and having major problems. it is old wiring.

downstairs has 3 cables. cable one red, black, cable 2 red, black, cable 3 red, black. The back plate is L1,L2,L3 AND L1,L2,L3.

UP STARIRS has 4 cables. cable one red only, cable 2 red, black, cable 3 red, black and cable 4 red cable only.

______________________
moderator
moved as posted in wrong forum

 

[breezer]

that's nice

 

[plugwash]

i take it you have/had two gang two way switches at both ends and you don't have a good record of the original wiring

it would appear that at each end you have a live coming in and a switched live going out

then two pairs of strappers between the two switch boxes

something like
[code:1]
.----------.
L -----switch switch-------SL
'----------'
.----------.
SL-----switch switch-------L
'----------'
[/code:1]
my guess is in the upstairs switch the live and switched live are the two red wires that are seperate and in the downstairs switch the live and switched live will be in the same twin and earth cable.

first thing to do is to find the permanent lives. (use a multimeter and take care don't try to touch bare wires with the meter put them in chock block before turning on)

then check that the switched lives really are the wires we think they are by connecting directly to the locally availible permanent live

finally identify which strapper pair is which by shorting one end and using a meter on the other (do this with the power off)

whilst this arrangement should only be used with the lights on the same cuircuit it is very likely it has been done accross cuircuits giving a borrowed neutral situation. at the very least switch off all lighting cuircuits before changing any connections and if in any doubt switch off all power.

 

[tigershaun]

thank you ..... just had a look up stairs and the wiring has two reds from the same cable, which then leaves the other two with red,black.