2 Switch 2 Light Lighting Circuit - PLEASE HELP!

[CSutton]

Hi guys,
Hopefully you can help. I am renovating a house and have just switched my hall and landing light from a rose downstairs and a three spotlight light upstairs to standard decorative ceiling lights. The switch unit downstairs has two switches, one switches the downstairs light on and off and the other switches the landing light on and off. There is a switch upstairs on the landing for the landing light. For some reason I just can't work out how the cables should be aligned in the downstairs light in order to resume the correct operation of the switches and light. As I pulled the rose down the cables became mixed together. Can anyone please help? In the downstairs light I have 3 Neutral Cables (black), Live Switch Cable (Black with brown tape around) and 4 Live (Red) cables. Naturally I have 4 Earth cables too.

Many thanks in advance.

Chris.

 

[ricicle]

See if you can work it out from here

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

 

[ericmark]

Other than the earth wire it's common for colours to be mixed up with black wires being line not neutral so colours don't help.

this shows the normal method of wiring two way lights. However as you can see there are three wires between the two switches.

Back many years ago electricians noticed of the three wires one is a permanent line. As a result instead of using three wires they would borrow a line wire from another switch on same plate. In the days of DC this was not a problem but we use AC so doing this produces a large induction loop and messes up radios and TV's plus other items. So the practice was discontinued. I don't think anyone realised how many houses had been wired this way until we started to put RCD's on the lights at which point one started to realise although the Guides to the regulations said one should not do this it was still being done.

From the colours you say you have I will guess your house is one with just two cores used as strappers between the two switches? If this is the case then there are a number of considerations.

To use just two wires will generate mains hum with some items like the telephone and could stop broad band working correctly. But not normally a danger as such. However both switches need to be supplied from the same over current device. It is common to split lighting circuits so one fuse/MCB does upstairs and another downstairs it this is the case then either the circuits need combining onto one MCB/fuse or new cables run.

Most lighting circuits use some where a ceiling rose rated at 5/6A so the maximum MCB/fuse is 5 or 6 amp. With low energy lamps this is not a problem but with the silly 50W spot lights one can easy exceed the 6A maximum.

I am sure others will also answer you so now you need to decide I am right in my guess and if so where next. I can draw out how it's done with two wires but I would think there are other ways around the problem now with remote control switches etc.

 

[Chri5]

//www.diynot.com/wiki/_detail/...2w.gif?id=electrics:lighting:two_way_lighting

 

[ericmark]

I think this

Untitled

• ericmark
• 3 Mar 2012
• 1

is what you had?
I would not recommend continuing with that method of wiring. If the landing light and stairs light are from different fuse/MCB then a borrowed neutral can exist which is dangerous.

Products like this mean it is now easy to correct without running extra wires. All look here only problem don't think it will work with energy saving were done by B&Q.

 

[ban-all-sheds]

As I pulled the rose down the cables became mixed together. Can anyone please help?

I don't understand why you cannot use your knowledge of how lighting circuits work and a multimeter to identify which wire is which.

 

[CSutton]

Thanks for the replies guys. I'm still a little in the dark. I understand 2 way switching etc and the landing stairs diagram supplied below was helpful but in my setup I have more going on at the downstairs light rather than upstairs! I also have 4 sets of cables coming to the light not 3 which complicates matters further.

 

[ericmark]

In theroy each cable with twin and earth will relate to a single lamp and the triple and earth will be the link between switches.

In practice as I tried to show often line is linked from one switch in pair to another. Since this should not really be done one can't follow any set out system and it's just a case of ringing out the wires.

 

[CSutton]

This may help... The best I've got it to work currently is the landing light switches on and off from downstairs only when the light downstairs is also switched on!

 

[Chri5]

Try looking at each item as separate.

Basically you have two way switching x 2 at the switches.

For the ground floor light you would have main switch at ground and a cable from ground to next level to give the 2 nd switch function for the ground light.

For the 1st floor light you have the main switch for the light at 1 st floor, and a cable at ground for the 2nd switch function for the 1st floor light.

If all else fails disconnect all wires and find the 1 way switch for the relevant lamp, once you have one way switching then the cabling function should be clearer.

 

[CSutton]

The ground floor light is single switch operated only.

 

[ban-all-sheds]

This may help... The best I've got it to work currently is the landing light switches on and off from downstairs only when the light downstairs is also switched on!

Please stop just connecting things up in different ways hoping to hit on the right combination by chance.

Go back basics - identify which wire(s) is/are permanent live(s), which are switched lives, which are switch to switch strappers etc.

Draw out what you have, and you'll then be able to see how to connect it up properly.

 

[holmslaw]

..

 

[CSutton]

Thanks Holmslaw - I've done this but the upstairs light will only operate when the downstairs light is on with this combination - why does the downstairs light need to be on to operate the upstairs switches and light? -

Chris.