ECN Forum Forums General Topics of the Trade General Discussion Area 100 W HPS fixture issue

It is about 250 feet of 4/0 URD from PoCo transformer to meter base. Then about 40 feet of 4/0 URD from meter to house. And 425 feet of #2 URD from meter to pole barn where the light is located. I know that there is a substantial VD at the pole barn with any load running. But the light is the only load on the pole barn service at night when the issue occurs. I changed the light ballast and photo eye to 240 volt. Still shuts off when A/C in house starts or any other large load. It just baffles me that the A/C at the house affects the barn light.

Merlin:
Think about the Vd at the house when the ac starts, then use that voltage for a 'source' to calc the additional Vd in the 425' to the barn.

By any chance, is the ballast a multi-volt?....You could use the 208 volt tap if it is. That may be a quick fix.

It's the photocell not the ballast.

That's my bet.

It is a multi-tap ballast. What would that do under "no-load" circumstances by using 208 tap? I did change the photo-cell to a 208-277 volt cell.

IMHO, it should be OK, unless the no load voltage is 240.

Worst case, for the chance of blowing the ballast, it may be worth it.

To separate the issue from the photoeye and the light fixture, temporarilly bypass the photoswitch.

If the fixture still drops out, it is a significant Vd problem. If the lamp flickers or is not affected, then the photoswitch is too sensitive.

PoCo issue question. Was there any tree damage to the utility's lines prior to the lamp problem showing up? My thought is that a utility line may have gotten damaged and you now have low voltage under load.