Neutral fault with LED light fixtures

[Chastech]

Hi everyone, I'm new to the industry(Qualified a few months ago). I have a client with 6 LED light fixtures on the same circuit/breaker, 3 are working fine and 3 seem to have a neutral fault(230v live to earth,+/-90v neutral to earth and +/-130v live to neutral).
The rest of the installation seems fine(no tripping).
I was just wondering if there is a simple way to locate the fault.

 

[Chastech]

Sorry, forgot to mention all lights were working with incandescent bulbs, client replaced fixtures himself.

 

[snowhead]

client replaced fixtures himself.

That's the most important clue with this fault.

Where are you testing to get the unusal voltages, at the fixture or the Consumer unit?

forgot to mention all lights were working with incandescent bulbs,

Is that the clients opinion or had they tested L-N, L-E, N-E voltages before fitting the LED's?

 

[nicebutdim]

That's the most important clue with this fault.

Where are you testing to get the unusal voltages, at the fixture or the Consumer unit?

"3 are working fine and 3 seem to have a neutral fault(230v live to earth,+/-90v neutral to earth and +/-130v live to neutral)"

Seems as though they've tested voltage at each fitting. I wonder if they've looked for loss of neutral at loop out of #3 or into #4.

I'd be amazed if homeowner isn't responsible for this fault, by either pulling neutral out when changing lamps or re-terminating on its sheath.