Bkessler

Had a call today....... the more light's you turned on the brighter they all got and when the coffee pot turns on, whoa, get your shades. My voltage at the weather head/ meter socket and main breaker was 117 on A and 126 on B. Under heavy load it went from 117 down to 100 on A, and 126 up to 141 on B. All the grounded conductors were tightened down and examined at the panel. I disconnected the grounding electrode and hit it with the metal brushes and checked it for current and voltage and found nothing. I looked for a loose neutral in a plug or switch box and found all was well. I did a fop test on all the breakers, despite being fpe they were fine......Then she tells me it all started a two years ago when POCO installed the triplex AND a plumber removed a section of underground steel water pipe that went to the detached garage. Anyway after three hours I called POCO to come check the splice on the pole. I had to get to another job so I buttoned up, originally the call was an estimate to replace the panel and after asking her why she wanted to I suggested her problem was in the house not at the panel. I am still going to do the panel change but I am stumped for now on the goofy voltage.

What am I missing?
Thanks

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ron

Sounds like the transformer to me.

480sparky

I'd wait to see what the POCO finds. Sounds like it's on their end right now.

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In winter, why do we try to keep the house as warm as it was in summer when we complained about the heat?

slmcc1

I had a similar problem with the same symptoms. Under no load the voltage at the service panel was correct, as soon as you turned on the breaker for the inside panel the phase to phase volts stayed at around 245v. Phase to neutral was 113 on A and 131 on B. I checked the line side of the meter and voltage was ok. The neutral bar inside of the meter base had corroded and wasn't making solid connection on the load side of the meter.

220/221

First call is ALWAYS to the POCO in cases like this. Here, they come out for free. They throw a 1000 watt load on one leg and check voltage on the other. If the vltage spikes/drops significantly it's their issue.

You have a faulted/semi open grounded conductor.

Bkessler

That's it, I just got the call from the home owner the grounded conductor loose at the pole. If she would have told me about the triplex being changed it would have been the first call but I see so many where its a loose neutral in the house, and at first it seemed to be isolated to one mbc. thanks guys.

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waco

Good lesson here regarding the behavior of a system with a high resistance in the neutral, but not an open.

I figure, when the neutral is faulty, the more loads placed on the individual branch circuits, the more effect paralleling those resistances has. Overall resistance is decreasing, but the system is acting as a constant current source and voltage is acting more as an indicator than any sort of solid diagnostic aid.

Good stuff.

Bkessler

This was a good learner for me, I have had a few with a more obvious open grounded conductor before but this was took me an hour before I was real sure what the problem was, And turned out to be a great call because I am 90 percent sure they will have me replace the panel add a couple of new circuits and install all new devices and make up all the old connections.

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waco

Excellent!

Ryvan@CNH

I have seen so many broken N lines on some CNC presses we have but I always get odd voltages like 64v and 180v or so and a good way for CNCs or home PCs to go poof but hey its nice to say the PC board did not over heat do to the fan when it stop working when it needed cleaned.
1st thing on a PM list clean PC fans!