2 cables to each light switch

[alanabassett]

Can somebody let me know why there are 2 cables running to each light switch in my house?

 

[mrloy99]

Can somebody let me know why there are 2 cables running to each light switch in my house?

when you say 2 cables,do you mean 2 brown (or red) cables or do you mean 2 grey T&E cables with what colour cores?

 

[alanabassett]

when you say 2 cables,do you mean 2 brown (or red) cables or do you mean 2 grey T&E cables with what colour cores?

There are 2 cables each consisting of 1 red, 1 black and 1 earth wire.

 

[mouldy3]

If the blacks are joined together in a choccy block then one cable is the live and neutral feed in and the other will be a switch live and neutral to the fitting.

 

[alanabassett]

If the blacks are joined together in a choccy block then one cable is the live and neutral feed in and the other will be a switch live and neutral to the fitting.

Thanks for the info. The blacks are all together in a block. Why is it done like that? Why not simply 1 cable with live and neutral?

 

[mrloy99]

There are 2 cables each consisting of 1 red, 1 black and 1 earth wire.

are they connected in to any thing?I'm guessing that the 2 wires are connected to the switch and the blacks are connector blocked? Certain kinds of dimmer switches need a neutral,and sometimes its easier to wire this way for an outside light or wall lights,but most likely it was wired by a plonker.But I wouldn't worry about it as it has given you more scope for alterations and additions,without haveing to get to the switch again.

 

[mouldy3]

Thanks for the info. The blacks are all together in a block. Why is it done like that? Why not simply 1 cable with live and neutral?

You only need to switch the live of the circuit, normally you would feed the light fitting and only have one cable to the switch but in this case they have fed the switches, both ways are acceptable.

 

[alanabassett]

are they connected in to any thing?I'm guessing that the 2 wires are connected to the switch and the blacks are connector blocked? Certain kinds of dimmer switches need a neutral,and sometimes its easier to wire this way for an outside light or wall lights,but most likely it was wired by a plonker.But I wouldn't worry about it as it has given you more scope for alterations and additions,without haveing to get to the switch again.

All the switches are the same - 2 cables, the blacks are all in a connector block, the reds are connected to the switch. I expected to see 1 cable with the black and red both connected to the switch. Can you tell why there're wired in this way?

 

[andyb]

are they connected in to any thing?I'm guessing that the 2 wires are connected to the switch and the blacks are connector blocked? Certain kinds of dimmer switches need a neutral,and sometimes its easier to wire this way for an outside light or wall lights,but most likely it was wired by a plonker.But I wouldn't worry about it as it has given you more scope for alterations and additions,without haveing to get to the switch again.

Why would this be wired by a plonker?
This is a very common method nowadays with the amount of downlights fitted into homes.
Rather than have a joint box for the live feeds, switch wire and switched feed to the lights above the ceiling and in a room of say 10 lights, no indication as to its whereabouts, the joint is accessible and easy to test.

 

[mrloy99]

All the switches are the same - 2 cables, the blacks are all in a connector block, the reds are connected to the switch. I expected to see 1 cable with the black and red both connected to the switch. Can you tell why there're wired in this way?

you don't switch the neutral,Don't lose any sleep over it! It could be a good thing---you could always convert your switches to pir's so the light comes on automatically when you walk into the room and goes off again when you leave.

 

[alanabassett]

you don't switch the neutral,Don't lose any sleep over it! It could be a good thing---you could always convert your switches to pir's so the light comes on automatically when you walk into the room and goes off again when you leave.

Sorry, I still don't get it. Where does the additional cable run to? If there are 2 live, 2 neutral and 2 earth wires in each switch, why aren't there more wires in the ceiling rose

 

[mrloy99]

Sorry, I still don't get it. Where does the additional cable run to? If there are 2 live, 2 neutral and 2 earth wires in each switch, why aren't there more wires in the ceiling rose

how many are there at ceiling rose,including the two going to your flex?

 

[sivoodoo]

Having it all at the switch makes life easier, i will be doing it like this allways from now on. Just wish they would make switches that have space for the neutrals instead of farting about with connectors etc.

Sorry, I still don't get it. Where does the additional cable run to? If there are 2 live, 2 neutral and 2 earth wires in each switch, why aren't there more wires in the ceiling rose

1 cable with the live neutral and earth comes from the consumer unit, then to the switch, then on to the lamp.

 

[alanabassett]

I'd expect to see 4 lives, neutrals and earths in the ceiling rose - 2 for the the cables running to the switch, 1 from the previous light and 1 to next light - that's not the case there are only 3 of each. Confused.

 

[Spudnik]

To make matters a little more complex, if the circuit was looped through each switch then there's normally three T&E's in each one all except the last, where there would be only two.

Whether its looped through the rose or the switch there are normally only three cables to connect, but switch loops take a single cable to the rose.

 

[mrloy99]

I'd expect to see 4 lives, neutrals and earths in the ceiling rose - 2 for the the cables running to the switch, 1 from the previous light and 1 to next light - that's not the case there are only 3 of each. Confused.

maybe the one you are looking at is the last one in the circuit,ie no cable going out to next room?

 

[WarrenG]

Sorry, I still don't get it. Where does the additional cable run to? If there are 2 live, 2 neutral and 2 earth wires in each switch, why aren't there more wires in the ceiling rose

I think you confusion is the black neutral wire in the switch?

There are different methods to wire lighting circuits and therefore if it had been wired differently you may not of seen a black wire at the switch at all.

It is probably better if you try and get some info on different ways to wire lighting circuits.

Attached is a basic drawing for you of some ways:

http://www.tlc-direct.co.uk/Technical/DataSheets/MK/WiringDiagrams.pdf

Hope it helps!

Warren

 

[alanabassett]

Sorry guys - can I go right back to basics. Why are there 2 cables to the switches and why are the neutrals connector blocked? Why isn't there simply 1 cable to the switches?

 

[sivoodoo]

1. are you an electrician?
2. do the lights work?

If you are trying to modify the circuit in any way and you do not understand the concepts of what is involved then it is my moral obligation to avise you to seek profesional help. Get a spaky in, dont put yourself in danger!

 

[alanabassett]

I'm not attempting or intending to modify anything. I'm planning to change the switch and want to understand why it's wired differently to all the resources I can find on the internet. I am fully aware of my limits under building regs.