LED High bays flashing!!

[dlt27]

Hi all, any advice would be greatly appreciated.
Went to do some work at a factory unit on Monday ( changed 20 florries to LED battens and changed 20 400w metal halide to 150w LED high bays). The florries were fed from different circuits and different DB’s and the high bays were fed of one DB, but from different phases and through contractors. When changing the florries I noticed there was a tiny spark when the neutrals touched any earth. I measured between N and E a few times ant different fittings and all I got was 3v on the fluke so not borrowed neutrals. I thought it might be to do with imbalance of the phases, but not totally sure!
When I changed the high bays ( click roses so didn’t have to kill anything) they worked fine for two days, but today I got a call saying a couple had started to flash/ pulse. At first one did it for 2 hours then stopped then a different one started and stopped and by the end of the day they said 3 were doing it… All ZS’s for circuits were fine..
I just wondered what everybody thoughts were and what to try? Could it be a lost neutral?
Thanks again for any replies..

 

[westward10]

I had something similar on some warehouse flories a few years back, all was fine until load was put onto the system and they started dropping out. Cause was a broken neutral compounded with a neutral to earth fault.

 

[dlt27]

I had something similar on some warehouse flories a few years back, all was fine until load was put onto the system and they started dropping out. Cause was a broken neutral compounded with a neutral to earth fault.

I’ve got a feeling it’s something to do with neutrals, however the loads been reduced because swapped 400w for 150W LED’s. Original 400w high bays were fine.Thanks

 

[westward10]

The loads in my instance were others circuits the loads being welders.