2 Way Switch

[plh1604]

Hi,

I have a set of 2 way switches for my hall light (1 Upstairs, 1 Down)

Each switch has 3 wires inside excluding the earth, unfortunately it is old wiring and they are not all the same colours

Upstairs there is a Black, Red & Yellow wire
Downstairs there is 2 Red & 1 Black Wire (1 Red & 1 Black coming in 1 sheath and 1 Red seperate)

I changed the switch upstairs and it worked fine with the Yellow wire in the single hole at the top of the switch and the red and black in the holes at the bottom.

However when I went to change the bottom switch I cannot get the light to work, either both switches go completely dead if put the red or black wire that is in the same sheat in the top hole, and if I put the single sheath red wire in the top hole it blows the fuse on the whole lighting circuit.

Help.....!! I am without lights in the hall for the 3rd night.

 

[breezer]

I understand what you are saying, but as who ever wired it has done it with their own colour scheme it is hard to say what to do with out testing it.

How ever one thing that "sticks out" the yellow wire is NOT The common (as you would expect it to be, so it does not go in the top)

This is a "long way round" but it should work.

ALWAYS turn the mains off in between moving wires, as you said this does not count the earth wire

Connect the top switch with only 2 wires (one in the common (top) the other in L1 (tape the third wire) Get the light to work from just this switch

Now do the same down stairs (it will not work properly untill the third wire is insatlled)

The wire you have left must be the common,

Try the following for both switches
take the wire you have from the top of the switch and put it in L2 (leaving a wire in L1)

The third wire you did not use put that in the top terminal

________________________________________________

I accept no reponsability for your error misunderstanding of the above

 

[AttM]

The following assumes you have some means of testing for voltage and for continuity (like testing a fuse).
1. Identify the live wire. (Call this L)
2. Identify the wire going to the light fittings (it will probably be in the opposite switch to the live) (Call this SW)
3. Check the switches to find the common terminal, ie the one than can be connected to either of the other two depending on the position of the switch. (Call this L1)

Once you have done the above, and assuming you can find everything, you need to connect L to L1 in one switch. Then connect SW to L1 in the other switch. The other two cables are called "strappers" and should be connected to the other two terminals (it doesnt matter which). This SHOULD get you working again.

Ensure you turn the power off once you have identified the live wire.

 

[plh1604]

I have some limited testing equipment but not a lot of knowledge.

Is there any easy way to test which is the live and which is the one going to the light fitting......???

is it a voltage tester I need....??? how easy are they to use.....???

 

[breezer]

If you have one of those "tester that lights up when inproximity to mains" it will tell you which is live, but it will not tell you which is the switch wire or the common.

 

[AttM]

If you can test a fuse then try this. (power off of course)

Join the red and black together in the upstairs switch, then test at the downstairs switch for continuity (your tester should light up or beep or whatever when you get the right red wire). These two should be the "strappers" and should go into the bottom two connections (L1 & L2 I think), the others should be the live and switch wire and need connecting in the remaining connections

 

[breezer]

AttM, I dont think that will work, (may be wrong) I base this on the fact that that would leave the yellow wire going into the top, plh1604 did that first and it didn't work.

Who ever wired it has crossed a wire some where, thats a thought, plh1604 its a long shot, but in the loft above or near the light, is there a junction box?, whoever wired it may have put a junction box in the loft and you may be able to find what colour is connected to (changes to) what
As you said there is a yellow upstairs but not down stairs.

 

[AttM]

Good point breezer, the joint box may be the answer.
I would have thought that if plh1604 can identify the strappers he should be OK.
So, working upstairs and testing downstairs with the power off and all wires disconnected, joint each of the three cables upstairs in pairs (RED&BLACK, RED&YELLOW, BLACK&YELLOW)and test downstairs. Two of them should provide a circuit and these should be the strappers and be connected as I said previously.

All of this depends on the light fitting, switches, cables etc not having faults that cause the fuse to blow.

 

[plh1604]

ATTM / BREEZER

Thanks for your input so far.

I haven;t tried to rectify the problem yet as dark nights mean it is dark when I get home from work so will attempt it on saturday.

what do I need to do to test for a circuit when connecting the pairs of wires together - what is the piece of kit I need, I probably have it or can get it from a relative/friend, but could do with some tips on ease of use.

do I need to do all the tests with the power off...???

you will no doubt have realised I am a complete novice in DIY electrics.

Cheers
PLH

 

[breezer]

you can check for the live by using one of these

you can get them from http://www.screwfix.com/app/sfd/cat/pro.jsp?id=10307&ts=88268

(other suppliers are available) when held close (does not need to touch) a LIVE wire it lights up, so for this and ONLY this the mains will need to be on.
When connecting the wires as mentioned turn the electricity OFF

Another point to bear in mind, make sure that the screws that hold the switches in position can not cut the wires.

Personally speaking a multi meter would be better, but it would take a long time to learn how to use one properly.

 

[plh1604]

Thanks Breezer

I have recently been given a multimeter but as you say it looks a little complex to master - especially for such a novice.

If there are any quick tips on how to work a multimeter - as I say I have limited knowledge on how to use these things, but can follow instructions.

Any help welcome as always

Cheers
PLH

 

[breezer]

Actually there are.
A multi meter can check things like blown fuses / lamps batteries.
but to save me telling you i have found a site for you.

Have a read through it, and try it with household things, lamp, fuse battery etc.
DO NOT TRY ANYTING THAT IS LIVE

electricity gives no second chance IT KILLS, ALWAYS make sure what you are testing is dead, NOT YOU.

that link

http://www.doctronics.co.uk/meter.htm

 

[plh1604]

Hi,

I have managed to half get the light re-working but any further help to finish the job would be appreciated.

I can get the light working from the top switch only with the following wiring combinations:

Upstairs Switch
-----------------
Red in Top
Yellow in Bottom (left hole if looking at back of switch.)

Downstairs
-------------
Single Sheathed red in Top
Other Red in Bottom (Left hole)

or

Upstairs
---------
Yellow In Top
Black in Bottom (Left Hole)

Downstairs
-------------
Single red in Top
Black in bottom (left hole)

I can also get it to stay on constantly (i.e cannot be switched off at the top or the bottom) with the following wiring

Upstairs
---------
Yellow - Top
Red - Bottom (right hole)
Black Bottom (Left Hole)

Downstairs
-------------
Single Red - Top
Other Red - Bottom (Left)
Black Bottom (Right)

Any ideas.......???

Cheers
PLH

 

[plh1604]

Hi.

Forgot to mention - on the 2 wiring sets that get it working from the upstairs switch I have the third wire taped off in a terminal block.

I have also tried a variety of other combinations which have resulted in no light at all coming on, could it be a faulty switch....???

Cheers
PLH

 

[breezer]

You could have a faulty switch, since it worked before you touched it, it should still work now. Unfortunately your problem is like a jigsaw with two missing pieces, if it was one you could figure out what it looks like. There is probably a junction box in theloft where all the wires from both switches go to or it may be in the ceiling rose (improbable) if you could find it and post what colour goes to what (including thelight) I am sure we can solve the problem.