I have changed a light fitting that used to power an adapter for spotlights. When I removed the adapter, I had two cables coming out of the roof each with a earth, neutral, and live wires.

The only way I could make the new fitting work was to have a live wire in the live terminal, the two neutrals in the loop terminal, and the other live in the neutral terminal.

  • L to L terminal
  • Two N in Loop terminal
  • One L in N terminal

If wired any other way I would get either no lights or light always on and can't switch off.

I'd imagine one cable is from the breaker and the other from the switch (only one switch).

I'm in the UK.

Is this safe?

Its not wire length that was the problem just to clarify. It is having 2 live and 2 neutral wires, and the way i have wired them to work.

  • 3
    It sounds like an American switch loop. It might also be possible you are switching neutral, instead of hot. It works but is less safe for people touching the wires. Will let the UK experts answer.
    – crip659
    May 30 at 19:37
  • 1
    Can you upload a picture? May 30 at 20:04
  • @Lee, have you managed to create two accounts ? May 30 at 21:42

2 Answers 2


No, the problem is, there is now no way to de-energize the bulb for changing the bulb. That means when you are changing the bulb if you touch the bulb base on accident, you will get nailed.

I mean I see where that was the only way you could figure out how to do it... but that's mainly because you stopped when you found a way that worked :) If you had kept going you would have found 2-3 other ways.

First, identify which of the two cables is mains supply. You can do that by disconnecting and capping off one cable cap each wire off. separately, do not join them to each other), and wiring the other one hotshot into the lamp. If the lamp does nothing, you found the switch leg. If the lamp is on 24x7 now, you found the supply cable.

On the switch leg cable, the blue or black neutral needs to be taped or sleeved to indicate it is being used as a "live" wire. That's a UK code requirement.

So, the re-marked former neutral should go in the loop terminal with the supply live*. Now you have one actual neutral wire left, and one live wire from the switch loop. Those go to the lamp.

I would also note that UK 240V is sourced from 3-phase 417V, only 16% weaker than USA 277V (480V 3-phase). A lot of USA electricians, when they go to work on a 277V panel, they don't spare the PPE. Tested linemen gloves, arc flash cover-ups, workspace cordons, assistant on hand ready to cut power, the works. That's food for thought for anyone feeling cavalier about "it's only home power". Cut the main :)

* the USA requires using former-neutral in a backwards way like this, to make it more obvious that it is not a neutral, since it is live at all times. I'm not sure if that's a requirement in the UK.


Probably one cable supplies power and the other is a switch loop. The way you describe the working configuration sounds right except that the two L wires could be reversed in a way that will work but is not safe. For safety you need to determine which L wire actually is Live ie provides unswitched power, and that one must be on the L terminal.

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