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antoined · Joined: 23 Sep 2003 Posts: 1 Location: london

I have to change a landing light switch.
I have 3 switches for that landing light (first floor, middle floor and ground floor). The ground floor needs changing. Went to the local DIY shop and explained the light fixtures had 3 different switches. Was told to use a 2 way switch. Have wire the yello to L1, the blue to L2 and the red to C.
Can switch on/off, BUT if i switch on/off at one of the other location I cannot switch off/on back on that switch.
Any help welcome.
Regards

thescruff · Moderator Joined: 03 May 2003 Posts: 4419 Location: Bath

Depends how it was originally wired.

Normal practice is to wire the phase to common the other two go to L1 and L2.

Check the light fitting the red live wire should be in the ceiling rose and the blue/yellow are the switching wires.

better still post me your email and I'll send you a sketch.

Note!! the above has been edited by scruff as it wasn't very clear and could have become dangerous.

First on the forum I said switch the neutral, don't !!! You should always switch the phase wire, the reason being in a fault condition an appliance could become live.

scruff Cool

AlanE · Posted: Thu Sep 25, 2003 7:32 am Post subject:

If I understand correctly you have three switches controlling the landing light. That means you have two two way switches (with three terminals) and an intermediate switch (with four terminals).

Assuming that it is a two way switch that needs replacing as you CANNOT replace an intermediate one with a two way one. Easist way now to find correct wire for the 'C'ommon terminal is to put each wire in turn into the 'C' terminal and the other two into either of the other two - doesn't matter which ones. All wires are related to the live wire so no harm can result. Test the switch if it works ok you're finished. If not try one of the others in turn until it works.

The problem occurs because there are two main ways of wiring up two way switches PLUS each engineer has his own preference for the common. Had you marked the common in the old switch you could have just fitted this in same place of replacement.

Ah if only the hindsight came first!!!

Alan