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Old 07-14-2010, 12:51 PM   #1
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Home electrical issues


Maybe someone can put give me some insight into what might be going on. I live in an older home with a 100 amp service . From the meter poll to the main all is good on one leg. The other is fine till I put a load on it. Then the voltage goes considerable low. Everything has been fine for yrs and then one day all of this came about. I have turned off all breakers on that leg and checked them individually but I basically get the same reading on each one. What might cause the voltage to drop so drastically?

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Old 07-14-2010, 01:14 PM   #2
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I would expect that any device in your house that draws enough current to drop voltage like that to trip a breaker. My temptation is to call the electric company.

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Old 07-14-2010, 01:14 PM   #3
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Home electrical issues


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Originally Posted by rampage View Post
Maybe someone can put give me some insight into what might be going on. I live in an older home with a 100 amp service . From the meter poll to the main all is good on one leg. The other is fine till I put a load on it. Then the voltage goes considerable low. Everything has been fine for yrs and then one day all of this came about. I have turned off all breakers on that leg and checked them individually but I basically get the same reading on each one. What might cause the voltage to drop so drastically?
Have the power company come out for testing. There is a bad connection or damaged part of a cable somewhere. It could be anywhere from your panel on out. Have the power co come out ASAP and let them narrow it down for you.

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Old 07-14-2010, 01:28 PM   #4
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I've had the electric co. come out already and of course they only check up to the meter...everything from there is my responsiblity. I live in the country so the poll is a good 75 ft away from my house so between there anything could be wrong. I was just wondering if I had a bad outlet or fixture if it would affect the whole leg.
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Old 07-14-2010, 01:31 PM   #5
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Sounds like a bad connection on the main breaker if the POCO has checked everything up the the meter. Did they check inside the meter base?
Have the main breaker connections checked. If no problem is found call the POCO back. It would not be the first time they missed a problem on the first call.
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Old 07-14-2010, 01:33 PM   #6
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Quote:
Originally Posted by rampage View Post
Maybe someone can put give me some insight into what might be going on. I live in an older home with a 100 amp service . From the meter poll to the main all is good on one leg. The other is fine till I put a load on it. Then the voltage goes considerable low. Everything has been fine for yrs and then one day all of this came about. I have turned off all breakers on that leg and checked them individually but I basically get the same reading on each one. What might cause the voltage to drop so drastically?
Are you taking your voltage reading on the meter side of the main breaker and probing the wire directly? Is the service feed overhead or buried? Could be anything from a bad connection to a bad transformer.
Well, I guess we are all typing at the same time.....

Last edited by a7ecorsair; 07-14-2010 at 03:32 PM.
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Old 07-14-2010, 01:59 PM   #7
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I've had the electric co come out twice and they checked the meter and transformer each time. The line is overhead and is quit old. It runs through a tree line which I have trimmed but didn't do any good. I've actually checked the wiring going into and out of the meter. All is good there. I had a storm come through and got home and half the house was without power. Checked everything that I could think of and found nothing wrong. I saw a few cob webs in the main and blew them out and the leg came back on but was still really dim. I took each breaker out and cleaned the box out but still doing the same thing. I'm thinking that I should replace the overhead supply wiring and bury the new wire.
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Old 07-14-2010, 02:21 PM   #8
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The other is fine till I put a load on it. Then the voltage goes considerable low. What might cause the voltage to drop so drastically?
Bad connection.
Put a 10 A, 1200 W elec. iron and a DVM where the symptom is.
For each 50' of #14 copper back to the panel you should see no more than a 2.5 vac drop at the iron when it is switched on.
For #12 copper it'd be a no more than a 1.5 vac drop.
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Old 07-14-2010, 02:51 PM   #9
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Quote:
Originally Posted by rampage View Post
I've had the electric co come out twice and they checked the meter and transformer each time. The line is overhead and is quit old. It runs through a tree line which I have trimmed but didn't do any good. I've actually checked the wiring going into and out of the meter. All is good there. I had a storm come through and got home and half the house was without power. Checked everything that I could think of and found nothing wrong. I saw a few cob webs in the main and blew them out and the leg came back on but was still really dim. I took each breaker out and cleaned the box out but still doing the same thing. I'm thinking that I should replace the overhead supply wiring and bury the new wire.
Did the power company test at the meter socket with a load on it?

How are you checking the wiring going in and out of the meter? Are you just externally looking at the wires or was the meter off and you saw the connections?


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Old 07-14-2010, 03:33 PM   #10
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Re-read post #6 and tell us what you get for a reading on the wire with a load.
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Old 07-14-2010, 03:52 PM   #11
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Yes, both the electical co. and myself have tested the meter and the main with a load on and off. At the meter I have in the neighborhood of 125/125 w/no load. With load, 120/121. At my main I have around 120/116 with load and normal without. I do have a well in between the house and the meter which is another concern. The only thing I have tested it with is a multi-meter. I have physically removed the wires both from the meter and main and reconnected them to insure no bad connections. The good leg stays a constant under load, the bad leg usually goes anywhere from 90 to 105. If I so much as have 3 lights on that on that leg, they go dim. The house is old and the main is not labeled so I will have to map it.
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Old 07-14-2010, 04:15 PM   #12
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Yes, both the electical co. and myself have tested the meter and the main with a load on and off. At the meter I have in the neighborhood of 125/125 w/no load. With load, 120/121. At my main I have around 120/116 with load and normal without. I do have a well in between the house and the meter which is another concern. The only thing I have tested it with is a multi-meter. I have physically removed the wires both from the meter and main and reconnected them to insure no bad connections. The good leg stays a constant under load, the bad leg usually goes anywhere from 90 to 105. If I so much as have 3 lights on that on that leg, they go dim. The house is old and the main is not labeled so I will have to map it.
You don't have to map anything. If you are seeing the power drop that much at the lug then you have a problem before your service panel.
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Old 07-14-2010, 06:49 PM   #13
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This is a classic sign of a loose neutral connection. You said the overhead passes thru the trees. I would scan the length of the triplex looking for a bad spot in the neutral.
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Old 07-14-2010, 07:21 PM   #14
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Jim,
If the neutral was bad in the service feed wouldn't he have problems on both legs of his service? If I'm reading these right, only one leg (I assume the same leg) is reading low under load. To me, this would be a problem with the neutrals or hot for that side in or after his circuit panel, wouldn't it?
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Old 07-14-2010, 07:22 PM   #15
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the bad leg usually goes anywhere from 90 to 105.
With a 3 A load this would mean 10 ohms of resistance. Panel connections/wiring should have resistances in the milliohm range.


Last edited by Yoyizit; 07-14-2010 at 07:47 PM.
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