2 way wiring - or not?

[Gerry24]

Could do with a bit of advice from someone a bit more experienced in 2-way lighting circuits than me.

The customer has a guest house with 3 consumer units, one for the owners living accommodation and some parts of the guest house, one for the rest of the guest house, and one for the outside bits that include a number of small industrial units in the field behind. It was an old farm that has been converted.

He asked me to replace the downstairs switch on a 2-way arrangement with switches at bottom and top of stairs for lamps at top of stairs. The downstairs switch had a blanking plate on it which the customer said he fitted when the switch stopped working some time ago. The switch at the top of the stairs is a push button time delayed switch.

When I took the blanking plate off I found 4 conductors coming into the switch, i.e. L, N and cpc from a bit of T&E and one single neutral. The CPC was just loose but the L and both N's were connected together with a single bit of choc bloc to the outgoing conductors so all conductors, except cpc, were all connected together. The switch at the top of the stairs was working. The T&E is fed from a different mcb on a different consumer unit to the single N. The single N comes into the switch from another switch on the other side of the wall. All conductors then leave the switch and are buried in the wall all the way to the switch at the top of the stairs. I checked them with a trailing lead and there was continuity between the 2 switches.

But at the time delayed switch at the top of the stairs the N from the T&E was terminated in a bit of choc bloc and the L and single N were connected to the switch.

The customer wants me to fit another time delayed switch at the bottom of the stairs so that the lamps at the top of the stairs can be switched on from either location. I cannot figure out how to do this with the 2 separate circuits and the wiring currently in place.

Any advice would be gratefully appreciated.


Thanks.

 

[Paul.M]

It sounds like it was a 2 way lighting circuit. The N in the switch are probably live switch wires. Test in-between each switch with long leads to establish the incomer, both switch wires.

 

[Giovanni]

You'd be better showing a diagram to be honest, that explanation is a little 'Full' to be honest, have you tested at the position that was blanked to verify what is what?
So to clarify, the two switching positions are on totally different CU's? That's how that is reading to me...

 

[Giovanni]

If not then it sounds like it's just a two way, done the 'old way', with the N being S/L

 

[Pete@HGE]

I'm with Paul, unless I read your entry wrong, it sounds like a standard 2-way where the installer didn't have any 3-core on the van and has used t+e and a single. At least he didn't use the CPC as the 3rd core !!

 

[ezzzekiel]

prob single core at each switch are s/l and pl wth the two core as strappers

 

[Giovanni]

prob single core at each switch are s/l and pl wth the two core as strappers

The initial question is a bit....unclear, the concern here being that he states....." The T&E is fed from a different mcb on a different consumer unit to the single N" ............That's why I said what I did initially

 

[Gerry24]

Thanks for your replies. Sorry my explanation was a bit garbled. What is confusing me is that the N of the T&E isn't actually connected to the switch at the top of the stairs it is just terminated in a choc bloc. So, in effect there are only two cores actually connected, the L from the T&E and the single N. I could inderstand if the N from the T&E was used as a strapper but it is compleetly isolated from the switch! I guess I could try to use it as a strapper see if it works.

Also the fact that the single N is from a completely different circuit from a completely different consumer unit has thrown me a bit. But I guess it is just a classic case of a 'borrowed' neutral.

 

[robskiing]

Wouldnt have thought the single black was a neutral probably a permanent live one end and the other single black the sw wire the original installer has run out of red single try that

 

[electrify]

You mentioned 2 way using the cpc as third core I recently visited a large private school in Lincolnshire which had a new extention with underfloor heating with numberous zones the job was not more than a year old undertaken by a major an niceic contractor who needed 4 cores at set back stats he had wired in 3 core and earth , so he disregarded the cpc sleeved it brown and used it as live conductor and gave a completion certificate for his work- on closer inspection he had omitted also the bonding to the water and gas ,didnt lug the armoureds and no fusing of the bathroom fans on 10 amp circuits. --cowboys they exist at top level !

 

[SMB]

Thats sounds scary, im not too sure if i beleive it.

 

[electrify]

Well Iam telling no lies I took photo's to send to the NICEIC but the customer didnt want for me to contact them and invited them to return and fix --once the school was occupied because of CRB checks they were unable to return so we were paid to put it right and I have an invoice for that too- I did take the photo,s to an ECA meeting there were some sharp intakes of breath.
Now thats not the only one this last year, I found taped up connections in the roof of a new extention joining new to old --issued with NICEIC paperwork -this time I did send them to the NICEIC with photos-- that was june, I got a letter in return saying they were investigating --six months later we wrote to ask of progress-no reply-a month later we wrote again --return letter to say they had lost all previous communication and could I send copies of all correspondance and photos !--So as I always expected the NICEIC are only interested in making money -they dont give a ---- for the customer as mine has been waiting since June 2010. Advise join ELECSA not NICEIC they may talk the talk but when it comes to what they were set up to do ( incidently they were an offshoot of the ECA ) for the customer they are a real let down.

 

[whats an rb4]

dont forget the sws need wiring in parallel as they will both always return to n/o

 

[malcolmsanford]

Thanks for your replies. Sorry my explanation was a bit garbled. What is confusing me is that the N of the T&E isn't actually connected to the switch at the top of the stairs it is just terminated in a choc bloc. So, in effect there are only two cores actually connected, the L from the T&E and the single N. I could inderstand if the N from the T&E was used as a strapper but it is compleetly isolated from the switch! I guess I could try to use it as a strapper see if it works.

Also the fact that the single N is from a completely different circuit from a completely different consumer unit has thrown me a bit. But I guess it is just a classic case of a 'borrowed' neutral.

Gerry a lot of advice as been given and to be honest I don't think anyone here still understands if that BLACK you have there is in fact a NEUTRAL or a SWITCH-LINE, do you know which it is?

Not sure if you are working to a method or a process of elimination, the method working process is best and to do that you will need to start belling out which conductor goes where and take it from there mate. My first piece of advice is tell us is it a NEUTRAL or a SWITCH-LINE

 

[ezzzekiel]

The single N comes into the switch from another switch on the other side of the wall.

switch at the top of the stairs the N from the T&E was terminated in a bit of choc bloc and the L and single N were connected to the switch.

sounds like pl from switch through wall and feeding one switch, single neut at top is a switch live, the twin earth between the two is carrying live between switches and neut is now spare and at some point the two switching has been messed up, but i dont get why the t/e is fed from a db?