Opposite phase increase

[gashman63]

I have a residence I’ve been having trouble with. When the FAU(forced air unit) turns on, certain lights will get bright for about 2-3 seconds, then return to normal.
When nothing is running, each phase to ground is 124v at main lugs.When FAU turns on(B phase), voltage drops to 114v and A phase goes up to 134v. When lights in question(A phase), turn on voltage drops to about 117v and B phase goes up to 130v. I checked all neutral connections at neutral buss and all connections in j boxes associated associated with lights and FAU. Anyone run into this before?

 

[Hv&Lv]

All the time.
your on the right path, chase it to the meterbase then call the POCO

 

[ptonsparky]

Ditto.

 

[LarryFine]

It's definitely the neutral. Somewhere along the pathway, as you work your way toward the source, the voltage swings will stop.

As said above, your responsibility stops at the meter. If the POCO comes out, make sure the swing happens while they're there.

 

[texie]

Best to find it sooner than later or the magic smoke will come out of some of the 120 stuff. Intermittent/weak or open neutrals get expensive in a hurry.

 

[gashman63]

Found it. Every thing checked out on my end. Got the POCO out there. Found service drop rubbing along trees above car port. By the time POCO showed up, neutral had worn thru.

 

[LarryFine]

Found service drop rubbing along trees above car port. By the time POCO showed up, neutral had worn thru.

You need to have a chat with the branch manager.

 

[hillbilly1]

Georgia Power had a lot of issues with their older underground feeds, the neutral would burn in two. So much so, they had a transformer on a hand cart they would bring out to derive a neutral until they could replace the old one.

 

[Hv&Lv]

Georgia Power had a lot of issues with their older underground feeds, the neutral would burn in two. So much so, they had a transformer on a hand cart they would bring out to derive a neutral until they could replace the old one.

It’s called a “service saver” or “restore a phase”. Just about all utilities have them.
its basically a 1:1 split phase transformer.