Here in Georgia USA, we build homes (and commercial) based on specifications of the "Southern Building Code" which in turn specifies the "National Electric Code" of the "National Fire Protection Association" for electrical construction. Georgia Power does not use the NEC requirements for power distribution. It up to their customers to abide by the code, not them.

No Utility Company uses the NEC, because the NEC is not designed for Utility Companies.

NEC - The NEC specifies the rules & regulations for Residential and Commercial consumers of electrical power - updated every 3 years
NESC - The NESC specifies the rules & regulations for Power Generation, Grid Feed-In and Distribution of electrical power - updated every 5 years

There is some overlap between the two documents.

Adoption of the NEC by State ...
https://www.nfpa.org/-/media/Images...hash=5B170C036B1F08D491192F8E48C8D532AEAD5C6C

Adoption of the NESC by State ...
https://standards.ieee.org/content/...r/2012-nesc-state-adoption-reference-maps.pdf

5 States have not adopted the NESC:
1) California
2) Georgia*
3) Louisiana
4) Massachusetts
5) South Dakota

*NOTE:
The Georgia Public Commission and Georgia Power will have two keynote speakers at the latest 2022 Edition NESC convention.
While they don't formally adopt the NESC, they have a State Code for Electric Utilities, which is similar to the NESC, which they must obey.

"Adoption" allows for additions, changes or deletions by the LAHJ.

 

Lastly, if you work on this yourself, be sure to turn the main breaker off while you work. You don't want to have the breaker on while the neutral is completely disconnected as the only reference to the "center" would then be through the loads on each leg, L1 and L2. You're voltage fluctuations will be far worse.

Yes, well understood. I would definitely not consider attempting the neutral work without turning off the main breaker and confirming its proper operation. As long as the main breaker is in good working order, I feel comfortable with this job. If I find I have any doubts whatsoever, I'll either do it while the utility guy has the meter removed, or hire an electrician.

 

The safest approach, which is the one I use, is to treat all the wires as though they were live. In addition to being a way to avoid getting shocked because of a failed neutral connection some place, it is also protection against mis-wired points, where the black and white have been crossed, and those instances where the white wire should be red.
And consider the instances where the white wire from some connected load becomes open circuited from neutral. At that point it is a hot wire, but with a higher resistance, but with the full line voltage open circuit. I have seen that a few times.
And one more thing, which is about ground rods and the neutral connection: In this part of Michigan I have not seen any ground rods associated with the electrical service wiring of any residential property. None, except those added by the home owner in an effort to reduce electrical noise.

 

In this part of Michigan I have not seen any ground rods associated with the electrical service wiring of any residential property.

They are typically required in installations where a quality source of ground such as a metallic water supply etc, is not available.
N.A. code states a minimum of two 8ft rods driven at least 6ft apart.
Max.

 

Good news, bad news:

The city utility guys were here working when I got home. They used the "beast of burden" with the meter disconnected to test asymmetrical 80A loads on each leg, and found a max voltage differential of 6V between L1 & L2, meaning the neutral moved 3V, all of which is within their spec.

Despite not detecting any problem, they decided to play it safe and just rework every possible suspect. They replaced both crimps on the neutral drop, and checked and tightened all the joints to and from the meter - basically they reworked everything on their end. I'm so grateful that they chose to rework this stuff, since the problem had been intermittent and a single passing test didn't prove anything in my eyes.

In addition to their repairs, I was able to check and re-tighten the neutral connection in the panel while they had the meter out. So at this point, we've checked and reworked literally everything that I considered potential points of failure for the neutral.

The bad news is that there was no smoking gun, so I really have no idea if anything is fixed. I'll have to pay extra close attention for a few weeks before I'll feel confident that the problem is solved. Nevertheless, I'm really grateful for their quick and thorough response, and I'm cautiously optimistic that, whatever the problem was, there's a good chance it's fixed now!

 

Loose doesn't have to be "Loose" it just needs to be insufficiently tight. Slightly tight can be as big a problem as slightly loose. Semantics I guess, but the point is that, and I believe this to be the case, a loose connection can be tightened with merely a quarter turn and it's sufficient. But with accomplishing the slight turn you actually polish the connection somewhat, and may make a better connection. There's also the possibility there may have been some oxidation going on, limiting conductivity. Disturbing it may be all that was needed, and you may never experience a problem again for the rest of your life or the time you may spend in that home. The bummer will come when you find it hasn't fixed anything. That'll be the most frustrating of all. I hope that doesn't happen.

 

The bummer will come when you find it hasn't fixed anything. That'll be the most frustrating of all. I hope that doesn't happen.

Geez, I agree, I hope that doesn't happen.

I've seen a floating neutral once and fortunately it didn't end in a fire, although the tenant lost a television and a few lightbulbs from the fluctuating voltages.

The good part is that your neutral wasn't completely floating. There was some connection/conduction to ground. Were you able to measure the resistance from your neutral to the ground? Did that change after you cleaned up the connection?

 

Geez, I agree, I hope that doesn't happen.

I've seen a floating neutral once and fortunately it didn't end in a fire, although the tenant lost a television and a few lightbulbs from the fluctuating voltages.

The good part is that your neutral wasn't completely floating. There was some connection/conduction to ground. Were you able to measure the resistance from your neutral to the ground? Did that change after you cleaned up the connection?

I did try measuring it from the panel neutral to the ground rod a month or two ago, and the readings were lower than the accuracy tolerances on my meter, so not a meaningful reference for comparison.

As far as I can tell, the connection from the ground rod to the panel neutral is good. I'm less certain about the size, location, etc of the ground rod, but I'm pretty confident in its connection to the panel.

I have a hunch that the neutral to the panel may have been misbehaving worse than it would appear from the voltage swings I measured, and that it was the ground rod path providing a backup that kept things from being worse than they were. It's just a feeling though, no way to test or prove it based on available evidence...

...I mean, I suppose I could've deliberately disconnected the ground and then measured the neutral under load, but if my theory was correct, that would be a recipe for fried appliances, dead computers, or even fire! As much as I love testing theories, I don't wanna burn the house down in the name of science and discovery!!!

 

So far, so good!

Given that this was an intermittent problem to begin with, it'll be at least a few weeks before I'll feel confident saying the problem is solved. Having said that, this is 4 straight nights with no problems, so that's a good start at least.

If the problem comes back, I'll certainly be back here for more discussion. If not, I'll try to remember to post an update in a month or so. In the meantime, no news is good news.

Many thanks to all involved! I appreciate your help.

 

Thanks for the update!
Max.

 

Just to update again, it's been over a month now since the repairs, and we haven't seen any flickering lights or swinging voltages since! I'll probably stay paranoid (vigilant) for a while longer, but I'm fairly confident that the problem is solved.

I'll never know for sure precisely what the culprit was, since the pros reworked literally everything on the neutral from the pole to the breaker panel entrance, and I re-worked the neutral connection at the breaker panel entrance. Still, it does appear to confirm that it was indeed a neutral issue, and that it was between the pole and the breaker panel, not anywhere else inside the house.

Still have some more things to fix around here, but I'll definitely sleep better with one less thing to worry about! Thanks again to everyone who helped out in this thread. I really do appreciate it!

 

Thanks for the update.

Ron