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Old 12-26-2008, 06:07 PM   #1
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Neutral problem, not sure what to do now


I seem to have a problem with a bad neutral connection and I'm not sure how to proceed. I read previous posts with similar issues but they aren't quite the same situation.

Starting 3 days ago, when any major appliance comes on, all lights in the house either brighten or dim. In some situations (such as the boiler or refrigerator, presumably because of the initial surge) the lights return to normal after a second. In other cases, such as a blow dryer or electric kettle (steady draw), the lights remain brighter or dimmer until the appliance shuts off. I think the pattern is that lights dim if they're on the same circuit as the appliance, while lights on other circuits brighten.

I know that the dimming on the same line is normal. But this situation is new. I've lived here 24 years, and the brightening and "excessive" dimming just started 3 days ago.

I called the electric company and their guys spent a couple hours checking everything from the pole to the meter. They even replaced the ground rod. It's all good to the house, they say, so the problem is on my side.

I called my electrician but he can't get here until next Tuesday. With the holiday and the weekend the timing is tough for him.

I tried to narrow the problem by turning off one circuit at a time and checking for the brightening/dimming effect with it off individually. I figured if I could identify the circuit I could check the neutral connections all along it. However I went through every circuit, and the effect always occurred. This confuses me greatly. I'd have thought that if I shut down the circuit with the bad neutral, the rest of them would work normally. That didn't happen.

The guy from the power company said it's not dangerous. I think he said there was an 8 volt differential when he was metering while I reproduced the problem, though I'm not sure what that means. He did say to call them back if the dim/bright effect increased significantly.

Nothing I'm aware of changed just prior to this occurring. A month ago I replaced an overhead fixture, two days later my electrician replaced the main circuit box. This problem didn't occur during the 4 weeks until now.

I don't know what, if anything, to do. Is there any other way I can locate the problem? Do I just wait for my electrician? Is there really not any danger in the 4 days it'll take for him to come?

Thanks for any advice.

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Old 12-26-2008, 06:19 PM   #2
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Neutral problem, not sure what to do now


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Originally Posted by BataviaJim View Post
I seem to have a problem with a bad neutral connection and I'm not sure how to proceed. I read previous posts with similar issues but they aren't quite the same situation.

Starting 3 days ago, when any major appliance comes on, all lights in the house either brighten or dim. In some situations (such as the boiler or refrigerator, presumably because of the initial surge) the lights return to normal after a second. In other cases, such as a blow dryer or electric kettle (steady draw), the lights remain brighter or dimmer until the appliance shuts off. I think the pattern is that lights dim if they're on the same circuit as the appliance, while lights on other circuits brighten.

I know that the dimming on the same line is normal. But this situation is new. I've lived here 24 years, and the brightening and "excessive" dimming just started 3 days ago.

I called the electric company and their guys spent a couple hours checking everything from the pole to the meter. They even replaced the ground rod. It's all good to the house, they say, so the problem is on my side.

I called my electrician but he can't get here until next Tuesday. With the holiday and the weekend the timing is tough for him.

I tried to narrow the problem by turning off one circuit at a time and checking for the brightening/dimming effect with it off individually. I figured if I could identify the circuit I could check the neutral connections all along it. However I went through every circuit, and the effect always occurred. This confuses me greatly. I'd have thought that if I shut down the circuit with the bad neutral, the rest of them would work normally. That didn't happen.

The guy from the power company said it's not dangerous. I think he said there was an 8 volt differential when he was metering while I reproduced the problem, though I'm not sure what that means. He did say to call them back if the dim/bright effect increased significantly.

Nothing I'm aware of changed just prior to this occurring. A month ago I replaced an overhead fixture, two days later my electrician replaced the main circuit box. This problem didn't occur during the 4 weeks until now.

I don't know what, if anything, to do. Is there any other way I can locate the problem? Do I just wait for my electrician? Is there really not any danger in the 4 days it'll take for him to come?

Thanks for any advice.
The only responsible answer that I think anyone can give here is to call another electrician that offers after hours service and have them come out. This isn't something that someone without some reasonable level of experience should be trying to deal with.

I am sure there was only a 8V diff when the powerco guy measured it, but that was based on what you were running at the time.

Bottom line is that it really sounds like a neutral is loose somewhere, but the power co guy is very foolish telling you it is not dangerous. It is dangerous to your electrical equipment (anything that is plugged in) if nothing else, and at worst a fire hazard.

Please get someone out there now, not next week.

Jamie

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Old 12-26-2008, 06:31 PM   #3
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Neutral problem, not sure what to do now


The problem sounds like it is on the main supply neutral. If it is not on the POCO side then then it is between the meter and the main disconnect. The danger is if the difference goes greater than 8 volts you could damage or destroy electronics. The more power you use from one side of your service compared to the other side the greater the voltage difference will.

I would unplug any electronics that are not UPS protected until you resolve this.
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Old 12-26-2008, 07:12 PM   #4
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I would unplug any electronics that are not UPS protected until you resolve this.
I just ran down and unplugged my 2-week-old $1500 HDTV. I hope there isn't already damage. It seemed fine when we were watching late this afternoon.
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Old 12-26-2008, 07:21 PM   #5
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Neutral problem, not sure what to do now


8v is too high. A 3v drop maybe, and the closer you get to the panel the less the drop should be.

This problem is not subtle.

8v at 10A = 80w. If this energy is dissipated in something the size of a wirenut I'd think you'd already have a fire.

With most stuff turned on in the house, looking at the panel with the cover removed with one of those $60 IR meters will probably show you where it is.

Using a spreadsheet, for an 8v difference, with a 6A and 12A unbalanced load, the neutral connection would measure 3/4 Ω resistance (vs. a few milliohms), and 20w would be dissipated in this bad connection. 20w dissipated in a busbar should warm it up some.

Last edited by Yoyizit; 12-26-2008 at 07:42 PM.
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Old 12-26-2008, 07:39 PM   #6
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Neutral problem, not sure what to do now


Some HDTVs are marked 100-240 volts, and will accept any voltage in this range. You might be lucky.

This is an absolutely classic example of a bad neutral connection. If the POCO measured 8 volts at the meter, that is a bit high, but likely not the problem. Especially if its an overhead feed.

The real problem is very likely between the meter and the panel neutral. Frequently it's a loose connection at the neutral bus. The trouble with this is you're working very close to unfused conductors. A slight screw-up makes a BIG flash.

Rob

P.S. A ground rod will have very little effect on this problem.
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Old 12-26-2008, 07:46 PM   #7
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Frequently it's a loose connection at the neutral bus. The trouble with this is you're working very close to unfused conductors. A slight screw-up makes a BIG flash.
And vaporized metal particles flying through the air. This is absolutely NOT something an inexperienced person can do.

Jamie

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Old 12-26-2008, 11:59 PM   #8
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Neutral problem, not sure what to do now


A) Call the power company again. It's free and 1/2 the time it is on their side.

B) If it's not on their side, call a good electrician and explain the problem. Ask them to send out an old guy



Quote:
The guy from the power company said it's not dangerous.
Get that in writing and save the receipt from your TV. 8 volts is too much and can quickly turn to 80 volts.

Last edited by 220/221; 12-27-2008 at 12:03 AM.
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Old 12-27-2008, 08:53 AM   #9
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Neutral problem, not sure what to do now


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Originally Posted by jamiedolan View Post

Bottom line is that it really sounds like a neutral is loose somewhere, but the power co guy is very foolish telling you it is not dangerous. It is dangerous to your electrical equipment (anything that is plugged in) if nothing else, and at worst a fire hazard.

Jamie
Bingo!

We've set up tests in our shop with a variac in the neutral of a 120/240 volt circuit with a light bulb on one side and a space heater on the other. We easily shifted the entire 240 volts (well, minus a volt or two) to the light bulb (which obviously didn't last long).

Neutral problems don't heal, they only get worse. Replacing the ground rod will help only if the circuit has already deteriorated to the point that the ground rod is the main return path to the transformer.
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Old 12-27-2008, 10:53 AM   #10
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Neutral problem, not sure what to do now


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8v is too high. A 3v drop maybe, and the closer you get to the panel the less the drop should be.

This problem is not subtle.

8v at 10A = 80w. If this energy is dissipated in something the size of a wirenut I'd think you'd already have a fire.

With most stuff turned on in the house, looking at the panel with the cover removed with one of those $60 IR meters will probably show you where it is.

Using a spreadsheet, for an 8v difference, with a 6A and 12A unbalanced load, the neutral connection would measure 3/4 Ω resistance (vs. a few milliohms), and 20w would be dissipated in this bad connection. 20w dissipated in a busbar should warm it up some.
I gather that IR means infrared, to identify something hot? I'm afraid to touch anything in the box though. I don't have enough knowledge about what's safe and what isn't.
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Old 12-27-2008, 10:57 AM   #11
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Neutral problem, not sure what to do now


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8v is too high. A 3v drop maybe, and the closer you get to the panel the less the drop should be.
I should have clarified:
THe 8v they measured was on MY side of the meter, when I turned on a blowdryer to create the problem. The differential at THEIR side of the meter was less than 3v.
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Old 12-27-2008, 10:57 AM   #12
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Neutral problem, not sure what to do now


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I gather that IR means infrared, to identify something hot?
Yes, and that's the idea: non-contact = safer and much faster than measuring each voltage drop across bad/good connections.
But, go with your gut feeling about how to handle this problem.

For a 3v differential on their side of the meter they'd need 3000A differential current or a bad connection, unless I'm assuming something incorrect.
The voltage spec for MD is 114v to 126v at the panel, but I don't know of an "imbalance specification."

Seems like your PoCo has their own problems. Maybe they don't want to bite the bullet and want to put off a necessary repair until the first lawsuit is filed.
Possibly it's time to ask your neighbors who are on the same transformer if they are having similar problems.

Get what they say about the health of your electrical system in writing. Even people who are above the law don't like pencil and paper (or recording devices of any kind ).

Last edited by Yoyizit; 12-27-2008 at 11:10 AM.
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Old 12-27-2008, 10:59 AM   #13
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And vaporized metal particles flying through the air. This is absolutely NOT something an inexperienced person can do.

Jamie"
I would not attempt it. I wouldn't put my hand in that box to grab the Hope diamond.
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Old 12-27-2008, 11:08 AM   #14
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A) Call the power company again. It's free and 1/2 the time it is on their side.

B) If it's not on their side, call a good electrician and explain the problem. Ask them to send out an old guy
The main guy who was here yesterday seemed really good. He's around 50 yrs old, worked for the power company for over 20 years. He was here for over 2 hours, maybe closer to 3. He was very thorough -- he explained everything they checked, and from what I can tell it's everything from their pole to the meter.

Perhaps I will call them again but I really doubt this guy missed something.

My electrician is a retired power company guy. He's around 60 yrs old, now working full time on his own. The guy yesterday from the power company knew him well (they worked together a lot of years) and said he was good.

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Get that in writing and save the receipt from your TV. 8 volts is too much and can quickly turn to 80 volts.
Of course I didn't get anything in writing. The TV has been unplugged since early yesterday evening and won't be back on until this is fixed.
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Old 12-27-2008, 11:19 AM   #15
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Seems like your PoCo has their own problems. Maybe they don't want to bite the bullet and put off a necessary repair.
I could be wrong, but I really had the sense that the guy yesterday was thorough and good. He checked everything -- at the pole, on my roof, at the meter -- he kept me informed at each step, and he's certainly very experienced. I've never been more impressed with a utility worker -- after I came in to tell my wife the situation, I even said how good the guy was. Of course it could be impression rather than reality, but that's what I thought.

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Originally Posted by Yoyizit View Post
Possibly it's time to ask your neighbors who are on the same transformer if they are having similar problems.
I called the immediate neighbors -- they don't have the problem. Even after asking them to watch particularly for it, they report no symptoms.

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Originally Posted by Yoyizit View Post
Get what they say about the health of your electrical system in writing. Even people who are above the law don't like pencil and paper.
Of course the guy is long gone so I can't do that now, unless I call and ask for another visit.

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