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Ceiling Circuit Mulimeter Reading is 135V Why Would This be?

Postby AED » Sat Oct 15, 2016 11:12 am

We have an old downstairs light which I don't recall has ever been used since we lived in our house. It's a conventional ceiling rose unit with a couple of neutral, three live and a couple of earth wires. Missus bought a ceiling light she wants me to fit. I thought it was prudent to see if the circuit was still live. There's a circuit breaker in the box labelled for the downstair lights. It seems to work for the lights and the ceiling rose is live/dead appropriately for the circuit breaker. So far, so good.

What puzzles me is the voltage I'm reading. For that ceiling light, where I thought I should be seeing 240v, I'm only seeing 135v which I reckon explains why the ceiling light doesn't "work"? The on/off switch is in the kitchen which is a bit of a rats nest inside the box but the other switches work okay so I presume there's no problem in there.

To get to the wiring in the ceiling means I have to rip up the box room carpet and pull up the floor boards, something I'm loathe to do at this time for obvious reasons.

I'm just wondering then, if anyone might know why I'm only seeing 135v where I'd expect to see 240v? Ideas appreciated.
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Postby kbrownie » Mon Oct 17, 2016 8:34 pm

Between which conductors are you measuring the voltage.
Have measured between L and N, L and E, N and E?

Doing that would suggest where the fault lies!
If you have 240V at the fuse board between L&N and L&E and 0V between N&E.
Then at the light fitting in question, you have a conductor out!
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