Family man
Member
- Location
- Oakes, North Dakota, USA
Could use some ideas on how and why.
I got a call that some office propane heaters were not working and got there and fan was working but no fire from igniter. Circuit board was giving code for reverse polarity or poor ground. Everything looked normal but 120 volts from neutral to ground. Tracing it back I found a feed through panel and I measured 120volts from isolated nuetral bar to ground. Tracing back again I find a switch gear fed from a transformer feeding four 120/208 panels going to main fuse in switch gear I find O volts from B phase to ground and 208 from other two phases to ground. Should mention that other test points read the same 208 to ground on A and C but zero to ground on B. All three read 120 to nuetral. I figured to find a blown fuse but all was good. I shut down all loads and it went back to normal. Then energizing one panel at a time I found that one panel created the problem. Then borrowed it down to one 20 amp single pole breaker when energized create the problem. It is in position 9 so it would be the B phase. It was labeled recepticles but could not find where power was lost on the floor. Not sure where the best place is to go from here. The ground is apparently energized when you turn that breaker on but no fuse blows it just assumes potential of b phase.
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I got a call that some office propane heaters were not working and got there and fan was working but no fire from igniter. Circuit board was giving code for reverse polarity or poor ground. Everything looked normal but 120 volts from neutral to ground. Tracing it back I found a feed through panel and I measured 120volts from isolated nuetral bar to ground. Tracing back again I find a switch gear fed from a transformer feeding four 120/208 panels going to main fuse in switch gear I find O volts from B phase to ground and 208 from other two phases to ground. Should mention that other test points read the same 208 to ground on A and C but zero to ground on B. All three read 120 to nuetral. I figured to find a blown fuse but all was good. I shut down all loads and it went back to normal. Then energizing one panel at a time I found that one panel created the problem. Then borrowed it down to one 20 amp single pole breaker when energized create the problem. It is in position 9 so it would be the B phase. It was labeled recepticles but could not find where power was lost on the floor. Not sure where the best place is to go from here. The ground is apparently energized when you turn that breaker on but no fuse blows it just assumes potential of b phase.
Sent from my iPhone using Tapatalk