1solar
newbie
Reged: 02/08/10
Posts: 4
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I have a 200 amp main service. I then have a 100 amp subpanel (240 volts) where I'm only getting 64 volts on one side of the service coming from the 200 amp main service. The other side of the panel reads correctly at 127 volts. Why would I be getting exactly half the voltage coming from my main panel? By the way, I'm reading 127 volts on all circuits in the 200 amp box so my problem must be in the buried cable between panels? Or possibly a bad neutral or ground? thanks
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3phase
Electrician
Reged: 09/09/02
Posts: 6451
Loc: Licensed Electrical Contractor...
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If you read 120V to Neutral and ground on one side and the weird voltage on the other, most likely the Line or "hot" leg with the weird voltage is bad. BTW are you using a Digital Volt Meter? It sounds like you are, with the Voltage reading given. If so then it might be a
"phantom voltage" which is really no voltage. If using an Analog or needle type meter it is still a bad Line on the weird voltage side.
You are reading 120V to neutral on both bars in the 200A panel, correct? Are you reading 240V across a double pole breaker in the 200A panel? If so, then I would suspect the buried cable also.
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Rule of thumb,Keep your thumb from under the hammer!
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1solar
newbie
Reged: 02/08/10
Posts: 4
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I'm hoping its a grounding or neutral wire issue so I don't have to dig up any buried cable (there's a couple hundred feet of it and I would'nt have the foggiest where to look for the break).
One of my lights barely flickers when I turn the 64 volt circuit on so it isn't phantom current.
I haven't tested for 240 volts across a double in my main, but I will. I have tested all breakers in the main on both sides and they all test 127ish.
If this were a cut in the buried line somewhere wouldn't the breaker trip? Or wouldn't I not get a consistent 64 volts? I'm an hour drive from my problem so I'll be back to check it on Thursday. thanks for the reply
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normel
journeyman
Reged: 09/20/07
Posts: 70
Loc: SC
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Problem may be in the connections for the subpanel, at either end, especially if Al wire was used.
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Gizmologist09
member
Reged: 02/08/09
Posts: 188
Loc: Palmdale, California USA
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Get WIGGY tester. They put a small load on the line to eliminate phantom voltage displays. easy to handle, tough and hard to screw up.
This is what the pros use as a first line. Digital analog meters are the second and I do have my Simpson 260 at the ready.
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1solar
newbie
Reged: 02/08/10
Posts: 4
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Aluminum wire was used and one of my neutral wires is mostly cracked where it goes into the clamp terminal do to a settling and twisting problem with my service stand. I think the neutral wire in ? has 4 or 5 aluminum wires within it and 3 of those were cracked. So I'll start with the obvious neutral wire and go from there. thanks
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CabinConnection
Big Foot
Reged: 01/20/04
Posts: 18926
Loc: The Indianhead's Left Nostril....
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Quote:
...are you using a Digital Volt Meter?
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jdevlin
Carpal Tunnel
Reged: 09/09/02
Posts: 5968
Loc: Welland Ont. Canada
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If it was the neutral the problem would be on both lines. Look for a hot wire issue. Could be a connection issue at either end or damaged cable.
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Please do not PM with questions that can be answered in a Forum. I will not respond.
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1solar
newbie
Reged: 02/08/10
Posts: 4
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Using a digital meter.
I'm hoping its not a damaged cable, but like you say if it was a neutral wire issue the problem would be on both sides. thanks
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MCA
Super Handyman
Reged: 03/09/06
Posts: 2382
Loc: Illinois
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Quote:
If this were a cut in the buried line somewhere wouldn't the breaker trip?
No, there is a chance it might trip, but it will need to be a solid enough fault to produce enough fault current to trip a breaker. There may not even be a short, or there may be an arcing short that produces low level faults, not enough to trip a breaker, or it may be leaking some current to the ground, but not enough to trip a breaker.
Did you test for 240 volts between terminals of the double pole breaker feeding the underground cable? Could the breaker be bad?
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