2 way lighting

scottie2h · May 1, 2012

can you help?
my mum wants me to put a new light switch at the top of her stairs and one at the bottom. i came to do this but behind the switch the cables stumped me a bit im fresh out of college and only know current wiring methods. behind the downstairs switch is my line going into the common and my neutral to l1 and a red cable bridged between my l2 and the common then upstairs is a red to common then line and neutral to l1 and l2, has anyone ever seen this and how does it work like said im newly qualified and have only ever seen a 2 way done with 3 core and cpc. ca you help??

scottie2h · May 2, 2012

im probably gonna have to run new cable cos the cpc upstairs has been cut back, but i know ill probably come across this way of wiring again in the future and just want to understand it, college only teaches you on nice new shiny things and never old stuff that your most likely to encounter. ill obviously get the fluke on it all after ive done it but the wires just don't match from upstairs to down so i cant understand how they're connected. and all links i can find online just show me the methods that i know with, m switch s connected with 3 core and cpc.

Darkwood · May 2, 2012

I only know of 2 methods and if what you say is correct and you are not mistaken (downstairs 2core only and you say 2way fully functional) then im baffled to how it works.

How do you test the 2way???? i assume you are switching one switch on then going to opposite and switching off (repeated twice more), ive seen some just go to switch A and turn it on & off then walk to switch B and turn it on & off (this wont check both strappers).

Await the pics.

telectrix · May 2, 2012

as ^^^^ pics required, then an answer might be forthcoming.

Dave 85 · May 2, 2012

"My neutral is going to L1"
"Im a qualified electrician"

College without experience = pointless excercise

In answer to your question mate, you dont need to know what does what to replace a lightswitch just wire the new one the same as the old one....

Knowledge without common sense = useless

sorry pal

telectrix · May 2, 2012

a bit harsh, dave. the OP did correct himself over that neutral mistake. as he said, college have only shown him the loop in at light with a 3core between switches. you are correct in the college without experience. this will hopefully come to him with time working with experienced sparks. we were most of us green when we first finished college. i know i was useless for a while.

Dave 85 · May 2, 2012

Yeah fair point, no offense was meant. It reminded me of a guy I went to college with who bought a new house, went around taking all the switches off cos he obviously knew how to do 2 way switching, then went to put the new ones on and was a bit stumped. He had to call a proper sparky out at 10PM cos he couldn't get any lights working.
Surely anyone with a little bit of common sense would have just done one switch at a time, one wire at a time. I still do that now when replacing multiwire switches.

telectrix · May 2, 2012

colleges don't teach common sense. that's why H&S is so stupid at times. the best example i have had was in a dole office refurb. false ceiling at 8ft. no steps allowed on site, mini towers to get 2ft. off the floor. hard hat to be worn when head is poked up through false ceiling. busting grid etc.

mark80 · May 2, 2012

Here a quick diagram i did for you bud, can be confusing at first but we all got to start somewhere! Just bear in mind, the link that you take from switch for the hall light, to the common for the landing switch must be from the permanent live and not the switch line.

All that will happen if you get it wrong is that the landing light will only work when the hall light is turned on. Just a matter of swapping the link if this happens.

ackbarthestar · May 2, 2012

That set up will most likely lead to a borrowed neutral if the light is upstairs or controlling both upstairs and downstairs hall lights. If the stair switching is controlling the downstairs hall lights then it will definitely be a JB under the floor.

So you will need to get the switch line at the top switch down to the bottom switch if you use a 3-core between the switches.
Probably better to follow the existing wiring for the time being and pick up the cut back cpc with a crimp or connector.

Darkwood · May 2, 2012

mark80 said:
Here a quick diagram i did for you bud, can be confusing at first but we all got to start somewhere! Just bear in mind, the link that you take from switch for the hall light, to the common for the landing switch must be from the permanent live and not the switch line.

All that will happen if you get it wrong is that the landing light will only work when the hall light is turned on. Just a matter of swapping the link if this happens.View attachment 12162

The OP hasn't yet mentioned a hall light or that the downstairs switch is a 2gang... everything hes said relates it to been a 1gang 2way both ends. Had this been the set up any of us would have explained it for him.

mark80 · May 2, 2012

darkwood said:
The OP hasn't yet mentioned a hall light or that the downstairs switch is a 2gang... everything hes said relates it to been a 1gang 2way both ends. Had this been the set up any of us would have explained it for him.

Well how else would it be wired, have never seen it done any other way? The OP hasnt explained it very well and going off what he has said, it would seem impossible for the 2 way to work at current moment. Just assumed it would be wired the way i had posted, as this is the only way I have seen it personally.
For a two core to be used as strappers between the up and down switches, there has to be a live feed to the down switch. Whether this be linked from the switch next to it, or a feed taken from the nearest light.

Darkwood · May 2, 2012

mark80 said:
Well how else would it be wired, have never seen it done any other way? The OP hasnt explained it very well and going off what he has said, it would seem impossible for the 2 way to work at current moment. Just assumed it would be wired the way i had posted, as this is the only way I have seen it personally.
For a two core to be used as strappers between the up and down switches, there has to be a live feed to the down switch. Whether this be linked from the switch next to it, or a feed taken from the nearest light.

I know why you put it and possibly you could be right and wondered if OP had PM you or something with more info, as for the method you put... yes thats the standard method but also a lesser known method is used when converting a 1way to 2way by running a 3core to new switch point thats the usual one that baffles most if you never seen it before.

telectrix · May 2, 2012

as said before, pics will help. other than that, we're just pi$$ing into the wind

scottie2h · May 2, 2012

I apologise to all that have posted I should have explained a bit better, it is a 3 gang switch and it upon closer inspection it is just as mark80 has shown. im sorry for wasting peoples time from my poor description of the complete picture.

Darkwood · May 2, 2012

Well good call to Mark80 .... i was hoping for a undiscovered new wiring format that defied the laws of physics, and dont worry scottie as my earlier posts suggested i assumed you had to be mistaken somewhere, take it on the chin and dont tell yer mum you were confused

2 way lighting

scottie2h

scottie2h

Darkwood

telectrix

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Dave 85

telectrix

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Dave 85

telectrix

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mark80

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ackbarthestar

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Darkwood

mark80

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Darkwood

telectrix

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scottie2h

Darkwood

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