Hall and landing - light switching confusion...

[Allen]

Hello, I'm trying to figure out the wiring going to the light switches in my hall and on my landing respectively.

When I bought the house, each switch fitted is a simple on-off switch

- so you cannot switch the hall light off from the landing or vice-versa. However, I think the actual wiring inside the switch housings may be designed for double switches - enabling one to switch the hall light off from the landing or vice-versa. (At least, that is what I'm hoping.)

Can someone tell me how to determine (visually or otherwise) if the wires inside the switch housings are indeed as I am hoping?

I am only a DIY-er - not an electrician (as you surely surmised). I have done various domestic wiring alterations though, in the past.

Thank you. PS - I do have a volt-meter at hand if equired.

Allen

[The Natural Philosopher]

If so, there needs to be two three way cables - presumably unused - coming into each switch box.

You will need a pair of changeover switches to replace the single sitches at each location..

If not, you need to run two three way cables between the switch boxes.

How to wire them up is in the FAQ somewhere ISTR.

[Dave Plowman]

Below is a two way switch circuit which also shows how to add a third switch (the one in the middle). You'll see by this that all three terminals are used for two way switching as opposed to two for one way.

L1 L1 0===========0 0===========0============= Line | \ / | C 0================================O C \ / \ / 0===========0 0===========0============= Switch return L2 Optional L2 Intermediate

[usenet]

I would think it unlikely, I'm afraid, that wiring is in place for two-way switching. What is much more likely is that the *switches" are capable of two-way switching.

To allow two-way switching the normal way to wire it is to have a triple and earth cable running from one of the two-way switches to the other. Normally this will be coloured red/blue/yellow. If you have a cable of this sort present at both switch boxes (two cables if you want two two-way switches, one for hall, one for landing) then there's a chance you have the wiring in place. However, as I said, I think it's pretty unlikely.

If these triple and earth wires appear to be in place come back for more information on how to check them and then how to wire them.

There are other possible ways of wiring two-way switches, these may just be different ways of providing three conductors from one switch to the other (a Twin and Earth plus a single for example) or there is a completely different way of wiring it. However it's done though there will need to be three separate wires into the switch box for each two-way switch (excluding earth).

[Dave Stanton]

O

Agreed and whatever you do, DON'T be tempted to use the earth conductor as one of the strapping wires as I have seen done by a 'electrician'.

Dave

[The Natural Philosopher]

Yeah. Mind you, having wired all my smoke alarms faultlessly using three core plus earth, I now find that the alarms have no earths...Mmm. The temptation to use T & E with the earth being the interconnect signal wire must be strong if that's all you have on the van...

[Dave Stanton]

Only one to say, take pride in your work and work to the specs !!

Dave

[ARWadsworth]

I doubt it will be possible to do what you want unless there are any spare wires in the back box. It would be easier if you gave us a description of what wires you have got inside the back box in order to give a definate yes or no.

-- Adam

adamwadsworth@(REMOVETHIS)blueyonder.co.uk

[Allen]

Thanks to everyone for the help.

When I removed the actual switches today, I found that inside each switch housing (the one on the landing and the one in the hall) is two two 3-core cables coming out of the wall. In each switch-housing, one of the cables was not being used, since the switch fitted was a simple on-off switch for the local lightbulb.

The spare cable could be going from the hall to the landing couldn't it?

How do I find out if the wiring is set up for doubles switches (so the hall light can be turned off from the landing and vice-versa)?

I guess I could buy two double switches and wire them in. Would there be a wiring diagram in the light-switch instruction sheet?

Or is there another way I can determine if this is how the wiring is set up (and, indeed if the wiring is actually woking as intended) - without first buying the switches?

Please advise - amny thanks...

Allen

[Dave Plowman]

I posted one earlier on in this thread.

[Ed Sirett]

Which means having to write off the occasional half day for the sake of standards and medium/long term credibility.

[Allen]

I see you did, Dave - thank you. Unfortunately for me, I have to admit I'm not experienced enough to make any sense sense of it.

Allen

[Dave Plowman]

The terminals Com L1 and L2 refer to the three terminals you'll find on a two way switch. These should all be cabled to the second two way switch using your 3 way cable. The cable that was to the original one way switch is simply coupled across L1 and L2 on that switch.

[John Armstrong]

When you say one of the wires isn't used, do you mean that one of the wires (probably the black) from each cable are just joined together? If so, I would guess what you have is one cable is the supply, live+neutral+earth, and the other goes to the light, switched live+neutral+earth. ie it is used, just not connected to the switch. If this isn't what you have, what do you have? What colours are connected to what? A look at the wiring into the light fitting would give useful info too (one cable or more?). There are various ways the lights could be wired up.

If what you want is two switches downstairs and two switches upstairs, you would need two runs of three core + earth cable between the switch points, which you don't have. It would be simpler to modify the existing wiring so both lights are on the same circuit and switched from both points, ie one switch downstairs, one switch upstairs, both lights are on and off together. Probably still need some new cable putting in though.