2 way switching configuration HELP

[Geoff1946]

Yes, one of the three reds is live.

I have separated the three reds - 

1 appears to be a perm live

1 seems to feed the rest of the upstairs and 1 seemingly feeds the light on the landing via the downstairs switch.

So basically that's the loop?

I think that's some way to solving the question then.

Note, this is part deduction, part guess work:

You have a live feed, from the same MCB, upstairs and down, the downstairs one currently just feeding the downstairs light switch.

This, with the link which was allegedly  lost, forms one of the strap wires of your two way circuit.

The two wires you have designated "spare" are hopefully the other two strap wires.

Two continuity tests will prove or disprove this theory.

If I'm correct, the lost link should be from the downstairs light live feed into L1 of the two way, the spare black into L2, and the red into C.

As I said, I've not seen it, part deduction, part guess work!

 

[binky]

look up 'conduit method' of wiring 2 way switching, I'm with Geof on this one, reckon live feed has been taken from downstairs light switch, linked to C on upstairs switch, with the other 2 cores for upstairs as the strappers?

 

[Evans Electric]

Dave  it may have been done this way  , judging by where you say the wires are .

 

[kerching]

I knew it wouldn't be long before he drew it up on the forums CAD system

for some reason we used to call those a Glasgow or Scottish two way....took me ages to work out how it functioned when I was an apprentice

 

[Evans Electric]

Never heard that description Kerch  ..... we called it a " Conversion  Two Way "   .        Started doing them in pyro   where the spec.....( NHS I think) ..  wouldn't allow  a connector in  the switch  boxes.  . 

I knew it wouldn't be long before he drew it up on the forums CAD system

I think the CAD system needs  adjusting ,  not very neat is it .  looks like a pencil & bit 'o paper jobby .!! :C

 

[Sharpend]

Was that cos yee cudne afford the threee core? 

I think the CAD system needs  adjusting ,  not very neat is it .  looks like a pencil & bit 'o paper jobby .!! :C

C ould

A rdly 

D raw

???

 

[Geoff1946]

Dave  it may have been done this way  , judging by where you say the wires are .

View attachment 9683

That's basically what I was trying to describe, except the extreme left wire isn't there. (Only one wire in L1 of the downstairs two way.) Upstairs and downstairs both have live feeds, route unknown but originating at the same MCB. 

 

[Evans Electric]

As you say , its difficult when you're not onsite  ,  can only guess .

I've seen quite a few switch boxes etc where  the wiring makes no sense what so ever  ...you start to think , am I missing something here  ...why all the wires . ?  

But then remember ,  we had an electrician on a new school job ...spent  half a day working on a  multi-gang switch  (12 way  possibly)  ...trying  to get  ONLY 2 way  grid switch in the box to  switch OFF in the same  up position  as all the other  1 ways .      Apparently he got it right once   because  he'd operated the other end  ,,but then it went wrong again !!!!  :C  

Last time I saw him he was operating a  Mr  Softy ice cream  van . 

 

[roys]

Last time I saw him he was operating a  My  Softy ice cream  van . 

And apparently he crashed that and now has Mr Whippylash

 

[Evans Electric]

Who knows  Roys.   :C

 

[DaveChase]

Dave  it may have been done this way  , judging by where you say the wires are .

View attachment 9683

This looks like it, apart from I have one less core at the downstairs switch

 

[DaveChase]

There is however, I seem to remember, only one CPC in either switch.

The cores are all accounted for upstairs but there is one missing downstairs.

I didn't go back today but I'm hedging towards CPCs used as live returns and one at the bottom broken off as it enters the box .....

 

[Evans Electric]

Ah!!  Its starting to sound like right lash -up !!!      

 

[Geoff1946]

There is however, I seem to remember, only one CPC in either switch.

The cores are all accounted for upstairs but there is one missing downstairs.

I didn't go back today but I'm hedging towards CPCs used as live returns and one at the bottom broken off as it enters the box .....

No, not necessarily, see my comment above and earlier outline.

It CAN be done with only one connection to L1 downstairs.   This requires separate live feeds to upstairs and down, which according to your posts you do have, plus the magic link which fell between the floorboards!

 

[Evans Electric]

You need to get some proper tracing done .         Ref;  my sketch   ... you may only have the "Lost"  jumper wire  as your  L at the bottom  ...the loop out may not exist .

As long as you have a live at the top .... three wires between  and a  S/wire to the hall  you should be OK.    

If one of them is an earth wire  then forget it .    

 

[DaveChase]

Right, so finally worked things out.

Turns out one of the the 2 T&Es in the downstairs switch had been used as 3 core with no CPC.

What looked to be a broken CPC was in fact the missing 3rd core in the strapper which, after managing to coax a bit more of it out of the wall, tested out to be live

The short link cable must have been the broken piece.

So, no CPC in the strapper and no 2 way lighting on the landing until they decide whether they want a new cable run switch to switch.

Thank you for all your help I have learnt alot and was about ready to give up!

 

[Sharpend]

well done Dave, everyday is a school day. 

 

[kerching]

So, a bare CPC as a live then?.....nice