Two gang switch troubles

[bensewell123]

Hi Chaps.

I've a current inside light into my garage. That works fine. I've added a two way switch and am trying to connect my PIR to the other switch and work as seperate switches / lights. So one turns the outside PIR on and the other turns the inside light on in the garage.

So i've wired the outside light and added the bare cable to the earth block on the socket. I'm left with a blue and brown wired.

The current switch is working fine in switch one and cabled as follows:

C = Brown
L1 = Red

I've tried adding the other switch as follows:

C = Brown
L1 = Blue

But this doesnt work so to test the lights i cabled the cables into the switch on switch one and something bizarre happened. Both lights worked but when the inside switch wasnt on the outside
one came on and when the inside light was on the outside one turned off.

Very strange any ideas?

I've uploaded a basic image, its really baffling me this one.

Untitled

• bensewell123
• 23 Sep 2011
• 1

 

[ban-all-sheds]

It's not at all strange.

It's all going wrong for you because you decided it would be OK to try and install things without bothering to find out first how it all worked.

With the PIR just connected to the unused gang in the switch nothing will happen - where do you think it will get its power from?

There is no neutral at a light switch, so you cannot power a new light just from there, and when you connected the PIR in your test you were putting it in series with the inside light.

Take some time out and read the info here:

//www.diynot.com/wiki/electrics:lighting

 

[securespark]

Yup. When the internal light was off, the neutral was back-fed to the switchwire, giving the outside light a complete circuit, but when the inside light was on, that "neutral" became live, thus no circuit and the OS light went off.

You need a neutral. But not just any neutral. One from that circuit.

 

[bensewell123]

thanks that was so helpfull

 

[ban-all-sheds]

I do hope that's not sarcasm.

 

[bensewell123]

so I Need to get a feed from the current lighting circuit by either getting it from the current junction box in he ceiling / splitting with a terminal block connector from current wiring to feed the new circuit. I might just out a new junction box in near where the pir light is

 

[ban-all-sheds]

Yup.

Remember junction boxes should remain accessible for inspection & testing - not usually hard to arrange in garages.

If the circuit has an RCD I would advise using a double-pole switch for it - that way if any water gets into the light and creates a N-E fault, turning it off will fully isolate it.

 

[bensewell123]

thanks think the junction box is the safest option for a novice like me

 

[ban-all-sheds]

That's nothing to do with whether you use a DP switch or not.

 

[bensewell123]

Just thought on. I have a plug socket near where i want the PIR. Could i just tap into this as a spur to provide the power for the light.

So would be a case of new piece of cable from the current double gang socket to a switch then matching up the colours in the switch and voila? I've added another plug socket before but this was plug socket to plug socket. Not sure if the light would would work this way? Otherwise balls to it its going in a fused plug.