i have wired my hall light up and it works fine.the problem is the upstairs light works when you turn it on and the same with the downstairs light.this is all good until you turn the downstairs hall light on and the upstairs light on from the same switch.go upstairs and turn the upstairs light off upstairs and it wont go off.what have i done wrong.

tonyrod911, August 2009

At a guess you have either a red or black (with red sleeve) wire in the COM terminal when it should be elsewhere, but it's difficult to tell without knowing exactly what you've been tampering with or which wires are going into which terminals.

From your description I would suggest getting someone in who knows what they're doing.

Adam, August 2009

Your terminology and problem description suggest a certain unfamiliarity with lighting circuits so consider an electrician for your own safety.

The normal arrangement is to have two switches on the same plate (two-gang) downstairs with one switch for each light. The upstairs light being wired for two-way switching from either switch station.

The downstairs light will have Live connected to the Com terminal and Switched Live running off to the ceiling rose to control the downstairs lamp from either L1 or L2 terminal.

The other downstairs switch will have a wire in the Com terminal (it may be a small loop wire from the Com terminal of the neighbouring switch) and two other wires, one each in the L1 & L2 terminals. These wires will run upsatirs and connect to the L1 & L2 terminals of the landing switch (either way round).

The Com terminal of the upstairs landing switch will have a wire running off to the upstairs ceiling rose (Switched Live) to turn it on and off.

The two way switching will be Live in at Com - L1 & L2 running to L1 & L2 of the other switch with the Com of that switch running off to the lamp. Operating either switch will change the status of the upstairs lamp.

Wikipedia Light Switch has simple (Red/Black) diagrams but the terminology is American and uses the expression "3-way" to describe a SPDT switch which might confuse.

Lord Finchley tried to mend the Electric Light
Himself. It struck him dead: And serve him right!
It is the business of the wealthy man
To give employment to the artisan.

Peccavi, August 2009