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Neutral to earth measured with a multimeter should be about 0V. Live to earth should be 240V. Difficult to measure safely, especially in a ceiling. Maybe temporarily put the wires into a junction block so there aren't exposed ends?
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The polarity is unlikely to make any difference. But yes, putting the ends in separate connector blocks and checking voltage to earth from either conductor should tell you which is which L-E 230ish volts, N-E 0ish V (it may have a few volts floating around on it).
There are a couple of cheap options on screwfix. Probably the only time I’d recommend buying LAP products, but seems silly to spend £50 on a voltage indicator just for one job.
Just be careful to keep the exposed metal bits of the prongs away from each other and your fingers!
https://www.screwfix.com/p/lap-ms8922b-ac-dc-2-pole-voltage-tester-with-rcd-400v/669hy
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jellybaby
Nef
@Nelly
Replacing some very old halogen transformer spotlights with newer ones that can take LED bulbs. It’s a timely job too as a few of the transformers look like they’ve melted.
I’m stuck now though because the old wires that ran into the transformer are both brown wires - no way to tell if one is live and one is neutral (which seems to be required by the new fixture). Is there anyway to tell which is which so I can fit the new one?
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