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Njuneer
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Discussion Starter · #1 ·
I am having some voltage drop issues at my house. Problem HAS been traced to the service and not in the house. PC was just out to swap out a service feeder that was 6 and 4ga to all 2ga but that did not change a thing and I was pretty surprised.

I was told that if we go any further, they want to install a meter monitor for a week to look at the issues. I have done plenty of testing and at 75A draw, I can get both legs below 10% or 108V. With a 100A inrush, I can pull it below 100V for 1-2sec. I realize inrush is a hard player so I am working with constant loading to prove my point.

At 100A draw, it is really struggling around 107-108V which is right on the edge. As I told them, if my constant draw is up and I try to start any motor, I have all sorts of problems and it is just getting worse. They are feeding 7 houses on a 50kva transformer and I am at the end of the run.

Where do power companies draw the line to upgrade a transformer, etc? I would really like to make sure this is an isolated issue and not something everyone experiences. I have never seen it this bad but I usually do not do this much testing.

At a modest 30A load, I am down 8-9V.
 

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if they don't charge, just ask the POCO to put the recorder on. They probably have one setting around collecting dust right now anyway.

sounds like they are overloading the x-former. If they aren't willing to swap it out, they need to do a load study on the transformer to determine if it is being overloaded.
 

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If the voltage drop is occurring mainly in the transformer due to heavy load then everyone will experience almost the same voltage drop.

If the voltage drop is occurring in the wires then the farther you are from the transformer the more voltage drop you will experience. More voltage drop (expressed say in millivolts per yard) occurs in a section of wire with more current going through it, all other things including wire thickness being equal. So most likely more voltage drop occurs between the transformer and the tap off to the first house and not that much occurs between the tap off to the second to last house and the last house.
 

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If the voltage drop is occurring mainly in the transformer due to heavy load then everyone will experience almost the same voltage drop.

If the voltage drop is occurring in the wires then the farther you are from the transformer the more voltage drop you will experience. More voltage drop (expressed say in millivolts per yard) occurs in a section of wire with more current going through it, all other things including wire thickness being equal. So most likely more voltage drop occurs between the transformer and the tap off to the first house and not that much occurs between the tap off to the second to last house and the last house.

If both legs are about the same, even if low voltage, then it is not a loose neutral problem.
 

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Njuneer
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Discussion Starter · #5 · (Edited)
No, they installed a load tester yesterday and determined the neutral is a non-issue here. I was actually surprised that the 2ga wire did not do a thing.


I guess what my main question is here is, are my voltage readings considered an issue or par for the course and should learn to live with it? The PC will not indicate at what voltage and for how long will get something to change...

I would not be as worried with voltage sag with very high loads but seeing 8V drop at only a 15A load seems excessive IMO..

More than likely not much point in load testing at the X former if they just want to slide my voltage charts. I have multiple high load machines in the garage but I am careful not to over load anything or cause excessive load beyond what my service is. That being said, I just want good performance within the limits of my service. Everything in the service is good for 150A and probably would be just fine at 200A for short durations which is perfect.

That being said, when I see 105-110 volts at a modest load, I just get concerned because we are not even in the heat of summer yet!
 

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are you measuring your voltage at the service? What you have in your house is irrelevant (to the POCO).
Your voltage is to a point it is not acceptable, if that voltage is at the service.

Don't know where you live but some states/areas require no more than 5%+-. If you are in such an area, you are well below acceptable.

Where do power companies draw the line to upgrade a transformer, etc?
in my area: when they burn up from being overloaded (seriously)
so, where are you measuring these voltages and did the POCO take readings at the transformer while you loaded it?

have you spoken with your neighbors? Do you get along with your neighbors to where you could ask them if they are having problems or maybe even check at their house?

what is the size of the conductor before it gets to your service drop?
 

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Njuneer
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Discussion Starter · #7 · (Edited)
Voltage has been checked at meter can and indoors with no appreciable drop. Was able to easily drop voltage to 110V for the lineman with a 50A load at the meter can. In which he replies "how often does that happen?", being kind of smart but still ok to deal with. I wanted to tell him, 50A ain't ****, I can throw down 300A if you want to go there but I realize I cannot run my machines at full bore and only asking to get what I should be getting.

I have not talked with any neighbors but most are electrically illiterate and would not know what I was talking about. As long as something runs, it works perfect for them.

The service is laid out like this. 50kva Xformer to approx 150ft of solid open air conductor to a distribution pole (unknown conductor size). Taken from there 75ft on 2ga Al stranded to a spot pole. That spot pole branches to 2 homes, mine and another. Mine is now 2ga Al all the way to the house which is a 50ft run, the neighbor is about 75ft on 4ga Al to their house. SO, 2 houses feeding on 1 2ga cable. Issue is I technically have a 100A rated meter can BUT have been told even by the POCO that the contacts and head are the same for 200A, just the physical size of the box is bigger. Never the less, I still want to be able to get my full rates service within the tolerance.

Obviously I am asking every inch of my service here and they might just tell me I need to upgrade at my cost. I know they would bring more power free of charge but I would have to set another panel, wire, codes, inspections, all things I don't want to deal with right now.

One concern I have is they did say if more power is recommended, they would likely set me and 2 other homes on a 25kva transformer instead of upgrading the 50 to a 75. That really is not much head room IMO. That is only about 83A/240V continuous for 3 homes if I ran my numbers right. 25kva *.8 = 20kw/240V. I know there is a little head room in there but that 25kva just for myself would be preferred.

I guess I am assuming .8 for PF. Not real sure where that actually runs out here but most of my loads are motor loads so .8 would be pretty close.
 

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Njuneer
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Discussion Starter · #9 ·
Already ordered it. Original lineman showed back up to let me know they will be out in 1-2 days to install it. Though I am a little concerned about any excessive draw creating questions, I think the only way to get it fixed is to monitor it. At least I too will get to see how much instant power I use and what they would recommend for a service.
 

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Though I am a little concerned about any excessive draw creating questions
Seriously, stop thinking. You are thinking this to death. They are contractually obligated to get you the amperage you requested when you ordered your service. They are legally required to ensure that this is delivered at the proper voltage. It's on them, it's not your problem, and from what I have seen, POCO's are sincere in this, and take their job seriously
 

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Njuneer
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Discussion Starter · #11 ·
Well, I am just trying to protect my own equipment. As well, I know that when that baby Xformer goes boom, they will be knocking on my door first but maybe that is how we get a bigger one...:thumbsup:
 

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Seriously, stop thinking. You are thinking this to death. They are contractually obligated to get you the amperage you requested when you ordered your service. y
I think there is a situation involved though with the OP's service. If he has a 100 amp meter, how is his gear inside capable of allowing a 300 amp draw? Sounds like an illegal installation.

Though I am a little concerned about any excessive draw creating questions, I think the only way to get it fixed is to monitor it
 

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I think there is a situation involved though with the OP's service. If he has a 100 amp meter, how is his gear inside capable of allowing a 300 amp draw? Sounds like an illegal installation.
Then he is either going to have to down-size or go solar with his grow op
 

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When you are drawing very little current do you see your voltage readings vary noticeably anyway? This would be due to too thin wires up on the poles and/or an overloaded transformer, while your neighbors are using different amounts of power.
 

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Njuneer
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Discussion Starter · #15 ·
Yes Allan, that is why I called them originally. At only 20A of load, I am seeing voltage sag of 9Vish. Normal reaction would be to assume that if you really ask for some current, voltage would drop to unsafe levels. Kind of pointing to an overloaded Xformer or wire issues but it certainly is not a problem in my house.


Regarding the 300A draw, that was just an example but yes, I do have machines that will easily pull that BUT they are fused and breakered down to a fraction of that and controlling how much work they do. I have a couple 20kva rated machines and a 40kva rated machine. They are ALL protected correctly and I want power use like a hawk. Nothing illegal of about the install.
 

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Regarding the 300A draw, that was just an example but yes, I do have machines that will easily pull that BUT they are fused and breakered down to a fraction of that and controlling how much work they do. I have a couple 20kva rated machines and a 40kva rated machine. They are ALL protected correctly and I want power use like a hawk. Nothing illegal of about the install.

The fact you are drawing 100 amps continuously would show your service is undersized. So, what size are your SE conductors? what size are the feeders to the subpanel? What size are the branch circuit conductors to the machines you crank to draw 100 amp continuously (or the machine that draws over 150 amps).

while I won't say there isn't a problem with the POCO service, I think whatever is happening inside your house is complicating things more than you realize.

fusing a machine does not alter it's draw. While not loading a machine will help limit current draw, if you have a machine that is rated for 150+ amps or the 300 amps you said you have multiple machines that draw that much, I don't see you being able to load it little enough to reduce consumption by over 1/3-2/3 other than by just not turning it on.

so, rather than getting upset by the POCO, I would hope they don't realize you are illegally overloading their transformer and causing damage. Ya see, their equipment is rated for the listed load and you are listed as having a 100 amp service but have obviously altered the gear so you could draw considerably more. That causes damage to their equipment.
 

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Njuneer
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Discussion Starter · #17 ·
control draw by using VFDs, running only one machine at a time, and limiting the amount of work done.


Motor loads seem to be voodoo for PCs so for all intensive purposes, this is a big welder for working on my race car. People do this all the time and rarely an issue.

Just as a simple question, do YOU think a service should sag 9V with a 20A load?
 

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VFD's can create all sorts of issues on power lines. Without a meter that reads true RMS, your volt readings could be tricked by the way VFD's use power in a chopped fashion.

I have worked industrial controls for over 30 years. Often, issues blamed on voltage fluctuations have been traced to the use of VFDs. The older ones are more of an issue than many newer units. In industry, they sometimes install isolation transformers between the power feed and VFD drive. This helps filter the power and smooth, to some extent, the pulses and noise issues associated with some VFD drives.

If the power issues are in your home, then you should be able to crank up some power using non-VFD loads by turning on the stove and over, dryer, and other heating loads. If these do not create the same voltage drops you see when using your VFD drives, you might be using the wrong meter.

A power line monitor will tell the power company if thier equipment is faulty. It will measure true RMS voltage of each leg, along with virtually instantaneous current demand readings. Their equipment logs data for a period of time and will log events with the time they occur. Their equipment will be certified and you should be able to request a certification log for it from the power company, if you don't believe it works right. They keep these units in good working condition since they use them to identify potentially critical issue with their grid.

You could repeat your test while the power company equipment is hooked up. You can log your voltages and compare them with what the power company reads. This will show if your test equipment is working correctly.

Your main panel should be fused (or have a circuit breaker) rated at 100 Amps, if that is what your service is. If you pull more than that, you may very well pull the voltage down. Your power company may tell you to upgrade to a larger service or have you fuse things properly if you are drawing too much power.

You are correct in your understanding that long feed and undersized wires from the power company could result in lower voltages. If the power company determines that their power is flaky without you pulling more that 100 amps, then they will have to fix it for you. This might mean a larger transformer on the pole, splitting the power feed to fewer homes and adding a second transformer, or perhaps providing you with your own transformer.
 

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Njuneer
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Discussion Starter · #19 · (Edited)
Thanks Perry. I did use resistive loads for testing to maintain a 1.0 PF. Not even going over my allocated amperage, I could sag the line past 10%. Not all the time but I am hoping the PC can see that there "might" be an issue and simply run me some bigger wire or up a transformer one size to offer a buffer.

The lineman that visited did say that the 2ga Al that he just pulled over is the exact same wire that would be supporting a 200A service so for all intensive purposes, this service should have no problem with 200A because of the main service wire going to the breaker panel and the panel itself. As you know, wire ratings are a function of heat. More amperage, more heat, more resistance, more heat, until melt down BUT, even this system "could" sustain 150-200A for short durations without any concern at all.

The service wire is 2/0 Al, panel is 150A rated. These are continuous ratings. Again, I am not looking to overload my system and actually monitor things closely to ensure I am not being a nuisance. That being said, I think we all know that a breaker ha a large operating window. A 100A breaker can do full power for about an hour or even up to 150-200A for several minutes. I just want to make sure my voltage is not sagging to the point that it knocks stuff offline.

I might have mentioned above but the lineman and a good friend and design engineer said these old 100A meters are built exactly the same as the 200A meter. The head and lugs are the same but the physical box is bigger. Not saying I should be pushing the limits with it but just saying there is another reason why I should not see such sag on the line.
 

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where did you get the 2/0 al was rated for 150 amp continuous? It is allowed for a 150 amp residential service as the service conductors but the problem you have with that is a residential service is not really rated for 150 amp continuous. It is specifically allowed to use undersized wire because it is not considered to be a continuous use. Figure a resi service is rated for no more than 80% duty rating. That would mean, strangely enough, a 150 amp resi service is capable of 120 amps continuous.



So, now we have part of your problem. From all info I can find, 2/0 al SE is rated for 115 amps under use other than the exception as a service feeder for a residence. Who knows what else is illegal?

so now, we have discovered you have a 150 amp panel with a 100 amp meter. That alone is illegal so whether you illegally installed the panel or installed an undersized meter, there is an illegal installation there.

A 100A breaker can do full power for about an hour or even up to 150-200A for several minutes.
You have apparently never checked the trip curve for your breaker. Guessing just doesn't cut it.
 
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