The Weirdest Lighting Circuit yet

andy8758 · Sep 14, 2008

A cry for help - Customer in old house has a 2 wire lighting circuit. Simple Line/Neutral? Er no. One cable comes from a light in an adjacent room , and one cable goes down to a 2-way light switch.

The second 2-way light switch (at foot of stairs) seems to have a wire that goes "God-knows-where" - both switches have standard 2 strapper wires connecting them. So we appear to have no clear line and neutral. If I connect the wire from the adjacent light to its live/line - I get 55V across the 2 wires. If I connect it to the earth I get 0V. What the hell is going on here? Can anyone explain please?

If I cannot untangle this mess I will simply rewire a new twin and earth from other light, and re-wire switches.

Shakey · Sep 14, 2008

andy8758 said:
A cry for help - Customer in old house has a 2 wire lighting circuit. Simple Line/Neutral? Er no. One cable comes from a light in an adjacent room , and one cable goes down to a 2-way light switch. The second 2-way light switch (at foot of stairs) seems to have a wire that goes "God-knows-where" - both switches have standard 2 strapper wires connecting them. So we appear to have no clear line and neutral. If I connect the wire from the adjacent light to its live/line - I get 55V across the 2 wires. If I connect it to the earth I get 0V. What the hell is going on here? Can anyone explain please?

If I cannot untangle this mess I will simply rewire a new twin and earth from other light, and re-wire switches.

I have seen this in a house i am doing currently

There is a line and neutral at the rose, both two way switches have a single cable coming from one direction, and a twin and cpc going in another direction

Basically there is a JB in the loft, and its all split from there, so its replicating what you would normally get in the rose.

greekislandlover · Sep 14, 2008

Seen a similar thing in some flats built in the 1960's. All lights and switches go to one central box somewhere in the hall. Nasty - usually means a rewire.

andy8758 · Sep 14, 2008

Shakey said:
Basically there is a JB in the loft, and its all split from there, so its replicating what you would normally get in the rose.

Thanks for your thoughts - I searched for a JB - but I suspect someone had been "doing-something-themselves" and I had to re-wire one of the other lights where someone had wired the N to the SW/L

I did wonder if this someone had found and removed the JB but it still left me with a missing wire to the other switch.

I got some sort of admission from the lady of the house - her husband was absent. I have promised to ring him this week to discuss this. She also mentioned that a previous electrician had been completely flumoxed with the bathroom light wiring and resorted to re-wiring that. It is a very old cottage (about 300 years old) and the cable routing of the sockets was a bit of an oddity too.

I will give their rather full loft another search for a JB when I return to finish the job later this week.

wattsup · Sep 14, 2008

If the guy whom wired it 300 years ago was not part p qualified you really ought to get the council involved. It just goes to show how dangerous dodgy sparks can be, I would have expected it to last 500 years.