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OT- household electrical advice needed

Cole2534

Diamond
Joined
Sep 10, 2010
Location
Oklahoma City, OK
I'm dealing with some crazy voltage swings in my house's electrical so I am hoping PM has some insight.

The house is a '56 vintage with high-leg delta service, although the 208v is unused. When the A/C is off X/Z voltage is ~245v split evenly. When the A/C turns on there is a shift where one half of the split drops to ~108v, and the other increases to ~136v. This voltage swing is playing hell with our lights/fans/etc. What's even more odd is that the A/C unit is on It's own panel that is directly fed from the meter base, ergo it's draw shouldn't affect panel voltages.

The panel is probably original (pic attached) and obviously less than ideal, but I've only recently inherited this problem so it's all new to me.

Does anyone have some insight to this before I call an electrician?

Thanks, Cole
4905b8859bbcd34b54ccd7af4cfbbfb3.jpg


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208 and delta don't go together. Delta 3 phase is 220-260V or so and one leg will be a bit off from the other to ground.

I would use one of those infrared temp guns to check connections on the incoming wires from the pole to the AC panel. A bad connection will be warmer. Turn everything on at the same time to load the system as much as you can.

If the wires come in overhead look around the peckerhead closely. You often see splices that are exposed to weather here.

Wouldn't be a bad idea to just pull the meter base and check everything for tightness. Aluminum is bad for loosening up. You have copper in there, but copper does it too if you pull enough pixies through it.

I lived in a house that had some wild electrical gremlins. It was a rental so I never dug that deep, but everything solid state had a mind of it's own. Remote controlled ceiling fans would come on by themselves. Plasma TV would turn on with volume all the way up. Had to leave the dishwasher door open or the thing would start by itself. It ate light bulbs like mad. I would replace 10-20 bulbs a month in a 1400 sq ft house. CFL's would last a couple days. Had to buy incandescents.
 
I grabbed the amp clamp and DMM to pull some data.

A/C off x leg is 124v with a 1.7a draw and z leg is 122v with a 2.7a draw.

A/C on x leg is 108v with a 10.7a draw and z leg is 136v with a 1.7a draw.

Now when I say A/C, I mean the interior components like the air handler. The exterior components are on a diff panel and they're fine. So it seems to me like I have a blower motor on the fritz? I also should upgrade my panel, but damn I don't want to spend all summer in the attic.

Thoughts?


Garwood- when I checked the main feed I got 125v, 209v, 125, to ground in that order and 245v between any 2 legs. If that is not high leg delta, what is it?

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I had that same problem and the cnc's were not happy at all, checked everywhere, found nothing. then one day as I was walking to the house the AC fired up to a shower of sparks from the top of the power pole, bad connection on one of the service wires. fixed that and everything was right again.
 
What he said

had a similar issue years ago with gremlins
then the sparks flew one day on a jump pole
once that got fixed everything was fine
 
Is your neutral connection good?

If you have a weak neutral connection all of your appliances essentially form a weird voltage divider that splits up the voltage inversely to the load on that half of the phase.

Last I saw it you could plug in a toaster into one outlet and the lights would get very dim. If you plugged the toaster into an outlet on a different breaker the lights would get extremely bright.
 
yeah, thats definitely a connection issue some were, if nothing else thats a significant fire risk from over heating, hence you badly need to get it sorted. The comments about neutral being the key suspect are spot on too IMHO. Based on your comments so far, - your understanding of things, IMHO its time you called in some suitably qualified help.
 
You've lost the neutral.

Very common problem. Sometimes the power companies connection,
sometimes yours. Aluminum entrance cable is sometimes the culprit.

However....
As of late, Meth heads have been stealing them for the material
(both the copper and aluminum ones)

Look up the pole just above "cutters in hand, held over head" height.....:toetap:
 
The girlfriend mentioned the power company having been out here before to tighten some connections on their end.

If I've lost neutral, how can I check it?

I'll probably end up calling an electrician if it's not a simple check.

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There should be a solid #6 copper ground wire coming down the pole that caries your service transformer, clamped to a ground rod.

In your breaker box/service panel, neutral bus and ground bus should be bonded together, You should have a ground wire from ground bus or lug to a good earth ground, like a copper water service pipe, or ground rod driven in the ground.

IME fluctuating unbalanced voltages mean bad ground.
 
Where I live, the power company (American Electric Power) is responsible for the wiring from the meter base input and meter to the pole and beyond, so they service it for free. I own the ground rod and the meter base itself on into the house.

Larry
 
How dry is the ground around the ground rod? If it is too dry the soil will not conduct well. folks water their ground rods once a month in some areas. If the rod is as old as the panel I would add a new rod and tie it to the old one.
Bil lD
 
The problem is a poor neutral connection. I was caretaking a place in the country that had 4 residences on the end of a power line. The problem was wildly varying voltages depending on load balance. The first thing I tried was throwing rocks at the power line and seeing the lights flicker. Found it right off and the power company sent a truck and redid the connection. If I had not found it right off, trouble shooting would have been checking the neutrals and splices on the various electrical boxes on the place.
 
I think I know the source of the bad neutral. I attempted to add a receptacle to a portion of the house, but found out that the leg I intended to tie to was actually a switch leg. Damn. I already had my j-box set, so I just tied the wires back together with nuts and I bet I didn't get a good connection.

I had the GF turn off the breaker for that circuit until I can get back home to evaluate the situation. I didn't realize how finicky electrical could be, so I'm probably in over my head.

Thanks for the help guys!
 
Have your girlfriend get it fixed. Tell her to call the utility and explain that the lights flicker when the A/C is on. Then tell her to make sure that the A/C is cranked down to ensure that the compressor is running when they come to check the voltage at the meter.

They will find and fix the bad connection if it's on their sided of the service. Or they will tell you if it's on your side of the service, and therefore it's your responsibility.

Then you need to find a reputable sparky if they don't fix it.

The first step is free and just requires a phone call. Talk of a bad ground rod or a bad splice in a branch circuit junction box is just rubbish.

SAF Ω
 
They will find and fix the bad connection if it's on their sided of the service. Or they will tell you if it's on your side of the service, and therefore it's your responsibility.

The first step is free and just requires a phone call.
SAF Ω
I went through this exercise with my local utility. They pushed as hard as possible to put the blame on my side of the meter. I told the call center person that I had a voltmeter hooked right to the base of the meter lugs showing asymmetrical hots to ground under load. She didn't know what I was talking about, but finally agreed to send a service guy out. He took one look, climbed the pole, and announced that the center tap connection to the transformer had never been tightened. Well duh!
 
I went through this exercise with my local utility. They pushed as hard as possible to put the blame on my side of the meter. I told the call center person that I had a voltmeter hooked right to the base of the meter lugs showing asymmetrical hots to ground under load. She didn't know what I was talking about, but finally agreed to send a service guy out. He took one look, climbed the pole, and announced that the center tap connection to the transformer had never been tightened. Well duh!
I can get my amp clamp on the 3 wires coming from the pole. Those should be symmetrical under load, correct?

Phone call to the utility has been made. I'd like to present them with as much info as possible.

Thanks again!
 
Have your girlfriend get it fixed. Tell her to call the utility and explain that the lights flicker when the A/C is on. Then tell her to make sure that the A/C is cranked down to ensure that the compressor is running when they come to check the voltage at the meter.

They will find and fix the bad connection if it's on their sided of the service. Or they will tell you if it's on your side of the service, and therefore it's your responsibility.

Then you need to find a reputable sparky if they don't fix it.

The first step is free and just requires a phone call. Talk of a bad ground rod or a bad splice in a branch circuit junction box is just rubbish.

SAF Ω

YES

Ground hasn't much to do with it (it can affect how bad an open neutral gets as far as the voltage imbalance though).

Sounds like this is out on a farm or similar. You should, if the house really has high leg 3 phase, have 3 insulated wires and a neutral. Then neutral goes down every pole, usually, to ground, often a "butt coil" on the pole bottom, as well as coming in to the house..

If the neutral is any good from transformer to service, that voltage problem will not happen. The incoming neutral should tie to a bus in the box, and that should keep everything balanced..

I THINK I see it, but the pic when expanded is questionable. There is a lug on the right side of the right hand box that may be for it. Could connect to the other box through the conduit, which might be loose.

See if the power company fixes it. If not, get an electrician. Expect a possible "sales job" for a new service/breaker box, which might make good sense. I do not particularly like that one.

We had the same problem, and it turned out that our neutral was connected only by two corroded copper wires being twisted together, no clamps. Powerco fixed that very fast.
Y
 
I can get my amp clamp on the 3 wires coming from the pole. Those should be symmetrical under load, correct?

Phone call to the utility has been made. I'd like to present them with as much info as possible.

Thanks again!
I would try to measure voltage instead of current. There are perfectly good reasons current would be unbalanced when there are single-phase 120-V loads.
 
FredC wrote: "The first thing I tried was throwing rocks at the power line and seeing the lights flicker."

So, how many tries did that take? You're heaving a non-pebble/variable-weight random rock 25'/30' in the air and hitting a 2" diameter wire with enough force to jostle the connection?

I'm gonna need to see some video of that... :)

To the original topic -- neighbors had a party with about 80 high school band kids going on, and started losing power, but only in part of the hosue. Turns out the connection from pole to meter base was loose. Fortunately not heavily loaded, so it didn't get real hot and start a fire. Fixed for free by AEP (Ohio) the next day.
 








 
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