264 VAC Line to Line Residential

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MD Automation

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Engineer
At my house. After convincing myself I thought I saw a little brightening (and dimming) of room lights tonight I went and got my Fluke and measured L-N and L-L at my main panel. Worried at first about a weak neutral but that's not it. Balanced fine side to side (within a few tenths) but 132V L1-N, 132V L2-N and 264V L1-L2.

Not a measuring problem either, my Fluke and an old Radio Shack (you are free to laugh) agree to within 0.2 V

I think the brightening (and dimming) might be a sticking tap changer somewhere up the line?

I am on my own transformer, not that it should matter.

264 is exactly 10% over 240. I am not really worried much, but at what point would any of you wonder about calling your utility?

And who exactly would you call with such a specific nerdy question?

Is there a "running hot" option on the 1-800 number ;)

Press 1 if you smell gas...
Press 2 if you have no power...
Press 3 if everything is working 10% better...

Just curious.
 
MD Automation said:
At my house. After convincing myself I thought I saw a little brightening (and dimming) of room lights tonight I went and got my Fluke and measured L-N and L-L at my main panel. Worried at first about a weak neutral but that's not it. Balanced fine side to side (within a few tenths) but 132V L1-N, 132V L2-N and 264V L1-L2.

Not a measuring problem either, my Fluke and an old Radio Shack (you are free to laugh) agree to within 0.2 V

I think the brightening (and dimming) might be a sticking tap changer somewhere up the line?

I am on my own transformer, not that it should matter.

264 is exactly 10% over 240. I am not really worried much, but at what point would any of you wonder about calling your utility?

And who exactly would you call with such a specific nerdy question?

Is there a "running hot" option on the 1-800 number ;)

Press 1 if you smell gas...
Press 2 if you have no power...
Press 3 if everything is working 10% better...

Just curious.
Click to expand...
If one of our customers had that voltage it would be immediate response.
You should call if its above 255. Call the office and ask to speak with an engineer. Tell them your voltage, ask him if maybe a regulator ran up to max.
I bet they get there quick.
 
Thanks all. I just opened a ticket and we'll see if they call or swing by.

It's now down to ~250 to 255, but it swings around much much quicker than I feel it should (+/- 3 or 4 volts swings line to line). And my eye sees that in the basement incandescents.

Sure "feels" to me like something is up, and I'm pretty sure it's not in the house. I am also looking at a Fluke ammeter on one leg as the voltage varies - and that leg is drawing a whopping 6.4A. So likely nothing in the house causing crazy IR drop from one second to the next.
 
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ramsy said:
Open neutrals are checked with a load tester. Utility linemen use the beast.

You won't determine excess neutral resistance with a volt meter, much less a high-impedance meter.
Click to expand...
Yes sir, understood about using the beast to load one side of a service to get the neutral to swing.

The reason I mentioned worrying first about a neutral was the observation of lights brightening. A classic symptom of weakening neutral. For that situation, the first thing I was looking for was some large-ish out of balance L-N readings like 115 / 125. But still 240 (L-L). Of course, this can only happen with some (un)equal loading from 120 VAC house circuits. You won't get the powerful one-sided draw the beast can generate, but you still might notice uneven voltage balance.

However... excess neutral resistance can't get me higher than normal line to line voltages. Once I observed 132 / 132 and 264 (L-L) I certainly started to shift my thinking "upstream" towards a POCO problem, and not something in my house.

fwiw, in the last hour it's been down to 238 and now back up to 254.

Question... can my POCO query the smart meter remotely and ask for service voltage there? Just wondering.

I'll post up with anything I find out if indeed anybody calls or comes out in response to this ticket.

Thanks all.
 
For those still following along at home...

Was just downstairs and watched my Fluke go from 258 to 243 in under a second. Super obvious drop in basement lighting.

Kept my leads on Line side of main breaker and about 1 or 2 minutes later it jumped to 261 from 243. Again with obvious increase in lighting.
 
Have a recording voltmeter? It would be useful to have records to drop on the PoCo if they "don't find anything".

(Had a voltage sag problem maybe 20 years ago and dropped my ancient Dranetz 606 on the line. When the PoCo started doing the "we don't see a problem" I mentioned that I had records... "How did you make them?" "I put my Dranetz recorder on the line, it caught all sorts of things." "Uh, right. Would you copy the tape and send it to me? Here's the address." Had to get rid of the thing a few years ago, no longer repairable. Sigh.)
 
LarryFine said:
Well, motors and most modern devices with electronic power supplies will use less current, while resistive loads will use more. I would not worry until something pops. 🔥
Click to expand...
I thought resistive loads were at unity power factor and therefore used less amperes than inductive loads with low power factor
 
ptonsparky said:
Neutral issues will cause high/low line to neutral voltages. L-L voltage variations are not neutral problems.
POCO problem.
Click to expand...

I agree. And if the two L-N voltages remain balanced when the L-L voltage changes, then the problem is not on the secondary side of the distribution transformer.
 
Jpflex said:
I thought resistive loads were at unity power factor and therefore used less amperes than inductive loads with low power factor
Click to expand...
Real power is determined by volts, amps, and power factor. If you have two loads that draw the same current at a given voltage, and one has lower power factor, then yes, that load is using less power.

But the comment was about changing voltage. For a resistive load, more voltage = more current and more power. For a motor load, which with constant mechanical loading is roughly a constant power load, more voltage = less current and no change in power.

Cheers, Wayne
 
Last year we had out of spec voltage at a customer's house, not as bad as yours but I think up to about 255 was the highest we personally saw, but were putting a PV system there and it was getting up to 264 at the inverters and shutting them off. After a bunch of back and forth with the power company, then blaming the PV system, they finally found out they had a bad voltage regulator down the line....
 
MD Automation said:
Yes sir, understood about using the beast to load one side of a service to get the neutral to swing.

The reason I mentioned worrying first about a neutral was the observation of lights brightening. A classic symptom of weakening neutral. For that situation, the first thing I was looking for was some large-ish out of balance L-N readings like 115 / 125. But still 240 (L-L). Of course, this can only happen with some (un)equal loading from 120 VAC house circuits. You won't get the powerful one-sided draw the beast can generate, but you still might notice uneven voltage balance.

However... excess neutral resistance can't get me higher than normal line to line voltages. Once I observed 132 / 132 and 264 (L-L) I certainly started to shift my thinking "upstream" towards a POCO problem, and not something in my house.

fwiw, in the last hour it's been down to 238 and now back up to 254.

Question... can my POCO query the smart meter remotely and ask for service voltage there? Just wondering.

I'll post up with anything I find out if indeed anybody calls or comes out in response to this ticket.

Thanks all.
Click to expand...
Ours will
Still sounds like it could be a regulator problem.
Neighbors have any issues?
 
So, thinking to post a follow up to this thread, and assuming you have all been munching on popcorn and waiting for the next chapter of “The Customer says his Electricity is Too Good”…

As all suspected, the fault was/is on the POCO side for sure. As best I understand it, it was a stuck (presumably ON) capacitor (PF correction??). Stop reading now if you don’t want any more details.

I opened a ticket last night around 10PM, but nothing happened until a service tech showed up in a bucket truck this morning. He pulled the front of the outdoor meter panel and saw the same ~235 to 255 ish VAC, fluctuating more than he thought it should. After talking to each other for a little bit, and realizing that neither of us were complete nincompoops, he mentioned he wanted to check the output of the secondary (at the bushings) on the 25 kVA pole mounted transformer (replaced in spring 2020). Neither of us thought it would show anything different, but that’s where he thought he might look next (I guess to rule out problems with the underground lateral). But we all know that any problems there are going to cause lower service voltage (L-L), not higher.

Anyway…

He said he was going to try and reach it from my driveway because there was a lot of traffic on my 2 lane rural road.
I said yes, that’s because there is a detour of another road that is funneling more cars past my house than normal.
He laughed and said, yes it’s funny because that detour is some of our other crews working on some lines nearby.

Both of us starting thinking the same thing right away.

I said, “When did they start working on those primary lines”?
He said, “Yesterday”.
Then he said, “When did you first notice this problem”?
I said, “Yesterday”.

So then he jumped back in his truck and started looking up the locations of the nearest regulators or capacitor banks and getting on the phone/radio with the crew that was nearby. I am certain to have some of these details wrong, but from what he explained, while working on some nearby 3 phase lines (my road is fed from the “B” phase of those lines), the crews temporarily re-routed where they were fed from. And so, for the first time yesterday, my 7680 primary was getting sourced from a slightly different “path”. Sorry for the terrible explanation. But from this new source, it was now going thru a PF capacitor bank that my B phase was previously never fed from. Then somebody on his end looked up the cap on that B phase and it reported “ON” when it should not have been. So they sent somebody there to put it in manual and then turn it off (with a hotstick I guess??). He then said that would automatically generate a new ticket for somebody to go look at why that was not operating properly.

Anyway, that's what he tried his best to explain to me. But long story short, it's definitely on their end.

My service voltage is still a bit wonky, meaning up and down. I've not seen numbers like 264 anymore, but low 250s are common, and it dips under 240 as well. And it changes real quick sometimes, and not because any load kicked on or off in the house. That's what I'd like to see stop happening.

Kinda like this...

IMG_0022_AdobeExpress.gif

Just as the mains jump 8 volts in the small gif above, you can see the lighting brighten a bit. I expect this was happening to everybody on this leg, maybe ~ 80 houses.

I will wait a day or 2 till they finish whatever they are doing nearby and hope they restore the original feed to my B phase.

Thanks all, and bonus points for reading all the way down to here 😉
 
Last edited:
MD Automation said:
So, thinking to post a follow up to this thread, and assuming you have all been munching on popcorn and waiting for the next chapter of “The Customer says his Electricity is Too Good”…

As all suspected, the fault was/is on the POCO side for sure. As best I understand it, it was a stuck (presumably ON) capacitor (PF correction??). Stop reading now if you don’t want any more details.

I opened a ticket last night around 10PM, but nothing happened until a service tech showed up in a bucket truck this morning. He pulled the front of the outdoor meter panel and saw the same ~235 to 255 ish VAC, fluctuating more than he thought it should. After talking to each other for a little bit, and realizing that neither of us were complete nincompoops, he mentioned he wanted to check the output of the secondary (at the bushings) on the 25 kVA pole mounted transformer (replaced in spring 2020). Neither of us thought it would show anything different, but that’s where he thought he might look next (I guess to rule out problems with the underground lateral). But we all know that any problems there are going to cause lower service voltage (L-L), not higher.

Anyway…

He said he was going to try and reach it from my driveway because there was a lot of traffic on my 2 lane rural road.
I said yes, that’s because there is a detour of another road that is funneling more cars past my house than normal.
He laughed and said, yes it’s funny because that detour is some of our other crews working on some lines nearby.

Both of us starting thinking the same thing right away.

I said, “When did they start working on those primary lines”?
He said, “Yesterday”.
Then he said, “When did you first notice this problem”?
I said, “Yesterday”.

So then he jumped back in his truck and started looking up the locations of the nearest regulators or capacitor banks and getting on the phone/radio with the crew that was nearby. I am certain to have some of these details wrong, but from what he explained, while working on some nearby 3 phase lines (my road is fed from the “B” phase of those lines), the crews temporarily re-routed where they were fed from. And so, for the first time yesterday, my 7680 primary was getting sourced from a slightly different “path”. Sorry for the terrible explanation. But from this new source, it was now going thru a PF capacitor bank that my B phase was previously never fed from. Then somebody on his end looked up the cap on that B phase and it reported “ON” when it should not have been. So they sent somebody there to put it in manual and then turn it off (with a hotstick I guess??). He then said that would automatically generate a new ticket for somebody to go look at why that was not operating properly.

Anyway, that's what he tried his best to explain to me. But long story short, it's definitely on their end.

My service voltage is still a bit wonky, meaning up and down. I've not seen numbers like 264 anymore, but low 250s are common, and it dips under 240 as well. And it changes real quick sometimes, and not because any load kicked on or off in the house. That's what I'd like to see stop happening.

Kinda like this...

View attachment 2563139

Just as the mains jump 8 volts in the small gif above, you can see the lighting brighten a bit. I expect this was happening to everybody on this leg, maybe ~ 80 houses.

I will wait a day or 2 till they finish whatever they are doing nearby and hope they restore the original feed to my B phase.

Thanks all, and bonus points for reading all the way down to here 😉
Click to expand...
thats a jump in primary from 7,552 volts to 7,776 volts.

They still have a problem.

If its very intermittent, it could be an arcing regulator switch, or arcing disconnect somewhere on the line.
They need to ride the line out and find the problem, not just try to get out of something..
A good lineman would know primary voltage isn't supposed to fluctuate that much, that quickly.
 
Hv&Lv said:
If one of our customers had that voltage it would be immediate response.
You should call if its above 255. Call the office and ask to speak with an engineer. Tell them your voltage, ask him if maybe a regulator ran up to max.
I bet they get there quick.
Click to expand...
Problem especially with larger organizations is the preferred number to call for customer service is a call center, and they have limited suggestions for customers to try and from there it is send a work order to the appropriate service shop. How fast they may respond can vary from place to place though.

Smaller organizations you still often get a customer service rep that has no field experience but was trained to answer a certain amount of questions, but also have a greater chance of being transferred to someone that has field experience, and likely is part of the more direct supervision of the field crews.

Being a contractor and working with these crews from time to time, I do have direct contact number for some the supervisors and usually if I encounter a problem like OP has I just call one of them and explain where and what and they take care of it from there. But if it were a big company that served millions of customers that might not be as likely. Sort of that way with the local telephone system which is a part of a nationwide operation. I do have a direct number for one the local technicians, but he told me it is mostly only good for asking him questions. He can't make his own appointments unfortunately. His vehicle has GPS and they know if he is not where he is supposed to be. There is good and bad that go with that GPS tracking.
 
Yeah dealing with these things is often a real hassle because it takes you forever to get to someone who knows anything. The situation I talked about in post 14, after a bunch of phone calls, they send some nincompoop out who thinks it's such an emergency he pulls the customer's meter and leaves! Then even when we finally got connected with the "competent" guy it was still a battle to get him to acknowledge there was something wrong on their end and not a problem with our inverters.
 
I once caught such high voltage at my own place one time because of working on a piece of customer equipment in my shop, I happened to notice high line to line voltage and figured that it had nothing to do with what I was working on. Had no idea how long it had been running high though, just happened to take a reading for other reasons while it was occurring.
 
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