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Neutral problem, not sure what to do now

19K views 37 replies 10 participants last post by  s_anthony 
#1 ·
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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#2 ·
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
 
#9 ·
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.
 
#3 ·
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.
 
#5 · (Edited)
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.
 
#6 ·
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.
 
#7 ·
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

"Warning: The topics covered on this site include activities in which there exists the potential for serious injury or death."
 
#8 · (Edited)
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 :laughing:



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.
 
#14 ·
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.

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.
 
#16 ·
Wow, we sure get alot of fluff around something that is as cut and dried as this. The power company came and determined that the problem is not on their side. Sure, the guy mis-spoke when he said it wasn't dangerous, because it certainly is.

The REAL bottom line: Call an electrician. The neutral is loose at your panel. He will torque it down and be done. If the service conductors are aluminum, ask him to make sure there is an antioxidant paste, such as Noalox, on the wires.
 
#18 ·
...
The REAL bottom line: Call an electrician. The neutral is loose at your panel. He will torque it down and be done. If the service conductors are aluminum, ask him to make sure there is an antioxidant paste, such as Noalox, on the wires.
Okay, I'm heading to the phone book now.

The lines TO the house are aluminum, but the house wiring is copper.
 
#17 ·
No quicker help

Based on my fear from what I'd read here last night, I called my electrician as soon as I thought reasonable this morning to see if I could get him here quicker. Unfortunately he was gone for the day. I left a message conveying urgency but I doubt I'll get him here before Monday.

In the meantime we've unplugged everything non-essential, and we're keeping electrical use to the bare minimum. The only big draw items are the boiler and refrigerator.

Using my cheap digital multimeter, I've measured the differential at two outlets which come from different sides of the panel. The outlets are both near the end of runs, at the far side of the house from the main box.

When nothing is running the difference is about 2 volts. One side is around 119v, the other 121v. I've measured numerous times over several hours and it varies somewhat, from a low of 1v to a high of 4v. That's with nothing significant running.

When there's a draw on one line, the difference increases -- the greater the draw, the bigger the difference. A 60w bulb increases it by 1 volt or so. A blow dryer increases it a lot. I'm not sure how much, because when I saw the meter hit 130v on one side I shut off the dryer. I was afraid that too much of a difference would cause a fire.

When there's a draw on the other line, the difference DEcreases. A 60w bulb brings them both to around 120v. I didn't try the blow dryer on that side because of the previous effect.
 
#22 ·
Life is strange sometimes

Five minutes after I arranged for the emergency electrician, right as I finished my previous post here, the guy who did the original work called. He had been on an outside job that they had to stop because of the rain. With a little urging by me he agreed to come this afternoon. I think because he did the previous work that he'll be much cheaper.

I immediately tried calling the emergency guy but went into his voicemail. I left a message and also called his answering service to page him. Hopefully I can cancel before he heads out.

At the moment I've got TWO electricians on the way.
 
#23 ·
Five minutes after I arranged for the emergency electrician, right as I finished my previous post here, the guy who did the original work called. He had been on an outside job that they had to stop because of the rain. With a little urging by me he agreed to come this afternoon. I think because he did the previous work that he'll be much cheaper.

I immediately tried calling the emergency guy but went into his voicemail. I left a message and also called his answering service to page him. Hopefully I can cancel before he heads out.

At the moment I've got TWO electricians on the way.
Well it wouldn't hurt anything to have someone different look over the first guys work.

Was there a permit / inspection when he upgraded the service?

Jamie
 
#27 ·
Fixed!

The guy just left. (This is the original guy who replaced the box a month ago. Fortunately I was able to cancel the emergency guy before he finished his previous job.)

He pulled the meter and checked all the connections; everything was good. Then he had me create the problem while he metered -- with a blowdryer on, he said one side was 106v and the other 132v. So at least I could prove the problem to him.

Having eliminated all the connections, and assuming the power co. was correct, he concluded that it must be the line connecting the back of the meter to the circuit box. He replaced that line and the problem disappeared. There was no visible damage to the old cable, but it was bent behind the box and I suspect that the box pushing tightly against it broke some strands.

No more lights dimming or brightening, and when I measure at the outlets in the bathroom there's maybe a half-volt difference with the blowdryer on. (And I'm not sure if that's from the dryer or just the normal fluctuations I see with my cheap meter.) That's down from over 20v.

So all is good. I thank everyone very much for your advice. I appreciate all the help and I'm thrilled to have this resolved.

Thanks greatly!
 
#30 ·
great to hear of the fix Jim.



In MD it's 114v to 126v, which I assume means 228v to 252v. Does this mean one side could be at 114 and the other at 240-114, or 252-114?
Is this measured at the panel or at the outlets?
poco power is at the pole or last poco connection (they generally accept panel readings). the +- 10% is a national requirement. You may have more strict controls locally though. So based upon that, you can have as much as 264 volts leg to leg and the other numbers I mentioned from each leg to neut.

BTW, the PoCo receptionist who told me these numbers also told me that PoCo is under no obligations regarding the quality of the power that is shipped to its customers.
quality of power has nothing to do with voltage. They are responsible for voltage control.

basically, the POCO is allowed +-10%. that is federal regulations. Code has recommendations for voltage drop but that is all they are, recommendations. There is no requirement per code to maintain voltage.
 
#36 ·
If you havn't already - buy the extra warranty that comes with your TV :p

Most places will allow you to add it on after you've already purchased it up to X amount of days after - some up to 90 days.
 
#37 ·
Credit card warranty

If you havn't already - buy the extra warranty that comes with your TV :p
Most places will allow you to add it on after you've already purchased it up to X amount of days after - some up to 90 days.
We didn't get the extended warranty, but we bought the TV with a credit card that doubles the manufacturers warranty so we're covered for 2 years. I figure if there's any manufacturing defect it'll show up long before then. And 2 years from now there will probably be a TV that will make coffee and read the morning paper to me. :)
 
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