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Anyone ever seen this wiring arrangement?

TimmyTrumpet

My lighting circuit isn't done with typical twin and earth. Instead it has one twin core of brown and earth. The brown is my switch wire which is terminates at the L1 on the swich. The earth as you can see goes to loop terminal on the ceiling rose. Is that not strange. The other end at the switch is coiled up inside the back box with earth heating over it. One of those blues is constant power which I guess comes from the consumer unit. The other blue is neutral. At the light switch I have two browns on the common terminal. I guess this is feed in and feed out to next switch. The bit that puzzles me is a constant live wire which is blue in a block with neutrals and nothing in the earth terminal. It would be great if someone could help me understand it fully.

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Accepted answers

Doolittle51

The bit that puzzles me is a constant live wire which is blue in a block with neutrals

I assume you mean when they are disconnected from the terminal block? If so, then yes, 230V would be present between one of the disconnected Neutrals and Earth if any other switch on the same lighting circuit is turned on. Be careful messing around with things that you don't understand.

AMKC

That's just lazy wiring by a bad lazy electrician if they were even that. The Earth in the central connectors should have been in the earth terminal in the light and in the earth terminal in the box at the switch.

Yes you need to be extra careful around neutrals as there will be power in them if any light is on before it that shares it.

https://www.boards.ie/discussion/comment/123144107#Comment_123144107

"Yes it's a volt tester, pen type. It flashes red and beeps when voltage is detected."

Sounds like a decent one but yes always a good idea to test them on a circuit that you know is live first and then turn it the circuit off to confirm the tester it is working right. There was some dodgy makes out there.

That sounds like a good one though.

You can never be too carefully around electricity always turn it off at the Consumer Unit before working on anything like a light or socket etc. Only qualified electricians work on it live and that is only if we can not turn it off for some reason.

All comments

ted1

brown is switched live. , earth is earth. The two blues should be neutral. In and then neutral out to the next light.

Twin and earth is for sockets. Lights are often just single core.

Doolittle51

The bit that puzzles me is a constant live wire which is blue in a block with neutrals

TimmyTrumpet

Yes that is what I meant. When the cables were disconnected from the terminal block I was getting power through one of the neutrals with my voltage tester and I didn't know why. Thanks for your comment.

JL spark

What voltage tester do you have , if it’s a phase tester , throw it in the bin , buy yourself a cheap volt meter , The neutral been live is a back feed from another light on a circuit, or could be a shared neutral from another lighting circuit which was powered when you were working on that ceiling rose

TimmyTrumpet

Yes it's a volt tester, pen type. It flashes red and beeps when voltage is detected. As you probably guessed by now I'm only a DIYer but I got the job done. I changed a ceiling rose to a down lighter. I just thought neutral is neutral at all times. When I had wires disconnected from the rose and switch off I couldn't understand why one neutral was still live on my tester, and I obviously turned off circuit before I carried out my work 😁

AMKC

Yes you need to be extra careful around neutrals as there will be power in them if any light is on before it that shares it.

https://www.boards.ie/discussion/comment/123144107#Comment_123144107

"Yes it's a volt tester, pen type. It flashes red and beeps when voltage is detected."

That sounds like a good one though.

CrazyEric

When you disconnect the neutrals path back to the DB and the circuit is live and switched on then you can have 230v showing on the neutral wrt earth.