Araman

Araman · Oct 5, 2011

Last week I was asked to replace 4 fluorescent lamps on two circuits. The job went very smoothly and the first two were fitted and working in no time. The second two followed suit but by the time I was finished and ready to go the first two had stopped working, and nothing I do will get them working. I have, of course, checked my wiring and, to cut a long story very short, I can find 247 volts at the switch but only 128 volts at the lamp only 2.5 metres away and they will not come on. Anyone out there experienced this?

Rockingit · Oct 5, 2011

If you've wired them loop-through fashion, you might want to check that you've not accidentally wired them in series from the switch wire instead of the loop.

You need to expand on how you've wired them up.

malcolmsanford · Oct 5, 2011

You would seem to have a loose connection somewhere.

230 at the switch is there a neutral there or are you reading L-E to get this?

!28 volts at light where, L-N. L-E, N-E where?

malcolmsanford · Oct 5, 2011

Rockingit said:
If you've wired them loop-through fashion, you might want to check that you've not accidentally wired them in series from the switch wire instead of the loop.

You need to expand on how you've wired them up.

Or an even better one

Araman · Oct 5, 2011

I did not re-wire them, simply replaced the lamps. Previous electrician has not followed protocol of wiring colours and there are plenty of black live cables. Black/red at the switch which gives 247 volts. All connections are tight and L/N at lamp gives 128 volts.

Rockingit · Oct 5, 2011

OK, well the black - red at the switch is the switch live, which correctly reads the loop voltage. Half that same voltage at the lamps does tend to suggest to me that the switch live has been mixed up with the loop live out to the fixtures. Or as Malcolm said, you've got a loose connection to the lamp.

Are they wired on three way plates (like a ceiling rose), by any chance?

Araman · Oct 5, 2011

No ceiling rose. The cables simply protrude from the plaster direct into the 5ft fluorescent. I have checked all wiring I can see but now it seems I have to start lifting floorboards to find the fault, which, naturally I am loath to do, but I have checked all connections several times and nothing is loose. Many thanks to all who offered advice.