Voltage sag and the power company

viper · May 9, 2011

Residential service. Sagging 9% today and nothing new. that combines with some very odd noises through audio components that comes and goes, I was thinking of calling the power company to see if they would look into it. I can get it below 10% just by kicking in a few heating loads.

Regarding the noises, these are buzzing noises that come and go as well as pops. I have not put a scope on the line or logged anything but if they buck too hard, I certainly will but I would rather not waste time on it and just get them to fix it.

Ox · May 9, 2011

You seem to not be able to find the "Rant" thread in the Shop Owners and Managers board by yourself?

This now makes two threads in about 3 days that should have been posts in that thread.

Or is there a question posed that I didn't see?

???

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Think Snow Eh!
Ox

SND · May 9, 2011

Lower voltage for just your house or neighbors as well?

As to the audio, bad ground?

viper · May 9, 2011

Was a question OX. Sorry, I forgot to plug the questions..lol Basically was asking if people have experienced this and how the PC handled it. From my experience with my PC here, it should not be an issue and I was proved right. I decided to just call them and talk it out with their field tech since they have always been easy to deal with.

Basically, the house is a 200A service BUT there is 125ft between the main lines and the meter in which there is 6ga and 4ga Al wire. After I ran some calcs for him we determined that my voltage drop is being caused by the small Al conductors. They will upgrade the whole service to 2ga tomorrow AM. Could not be easier. We did some load tests along with just looking at lines.

Not to toot my own horn but I guessed the improvement almost on the nose. Told him that should get me another 5V at 50A draw. It came out to 4.8V. The real issue is when we have near 100A of load and the voltage sags pretty bad. Combine that Al wire sag along with main line sag and I think we found our issue!

Ox · May 9, 2011

4+6 alum for 200A? :willy_nilly:

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Think Snow Eh!
Ox

viper · May 9, 2011

Yeah, I am not all that excited about the 2ga Al but will take what I can get. he said if they need to do more, he will need to install a monitor meter to log all my usage for a week. I am just happy to get some improvement free of charge and no code guy involved. I really feel 1/0 should be hanging out there but I will let it roll for now and see what happens.

Ox · May 9, 2011

Yeah - 1/0 COPPER! :willy_nilly:

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Think Snow Eh!
Ox

viper · May 10, 2011

Well, They swapped it out today. installed 2ga ALUMINUM and then I also found out that 75ft of that service leg also feeds the neighbor... Needless to say, after some testing under minimal load, it is obvious that it made no difference. 60A was enough to pull it below the 10% tolerance. Right now there is only 20A of load and is down to 112V. I am now wondering if I should have them go ahead and install the meter head monitor and put the hammer down??

I have a couple machines at this place as well as a big welder, table saw, etc. I can punish that service if I want to. Just not sure how far I want to push this because they might just tell me that I have too much load for this service and need to get a complete upgrade.

I would have to argue that though because if you have a 200A service, you should be able to pull 200A and stay within their rated tolerance.

sfriedberg · May 10, 2011

viper said:
if you have a 200A service, you should be able to pull 200A and stay within their rated tolerance.

Totally agree. Your responsibility to make sure big motor or heater startup surges don't push you over the allocated 200A. My shop is on its own transformer so I don't brown out (and piss off) the neighbors.

But WTH are they doing feeding a 200A service with 2AWG? Sure it isn't 2/0 or 200kcmil (aka 200MCM)? Standard practice around here for 200A service, for burial in 3" conduit, is 4/0 or 200kcmil. I could see 3/0 or 150kcmil as marginal, and 2/0 as living dangerously for 200A. In fact, I think the NEC tables would flat out prohibit 2/0 for 200A industrial service. There are NEC downrating rules that would allow 2/0 for 200A residential service (NEC Table 310.15 B6), and you need to make sure the power company is not mistakenly applying a standard rule to your non-standard situation.

But 2AWG should be right out of the question for 200A service of any sort. :willy_nilly:

viper · May 10, 2011

You have to realize that open air conductors get some leadway. Plus the PC does NOT adhere to the NEC code book. They have a totally different book which I guess allows them to push conductors harder. That being said, I don;t care what they do as long as I can get my rated power with minimal sag

hitandmiss · May 10, 2011

Hi Viper,
What size is the transformer on the pole? 10 KVA? A 25 would be better.

viper · May 10, 2011

50 kva, serving 7 homes. Doing the math, there is NO WAY for everyone to get their rated 200A service.

Ox · May 10, 2011

I could'a swore you mentioned this is burried cable. Thus NOT air cooled, but you are right - if she hangs out for all to see - you CAN git away with undersized warr.

50 kva, serving 7 homes. Doing the math, there is NO WAY for everyone to get their rated 200A service.

While at the same time - maybe not "math" but I bet app tests have been done many times to chart the likelyhood that a 7 house circuit only ever averages 1/2 capacity at any one time. ???

Also noting that residences don't have "demand" issues either. The well (when applicable in a 7 house area) and sump pumps could be some of the hardest starters? Maybe the dish-worsher pump?

Again - somehow I had in my head this line was burried. ???

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Think Snow Eh!
Ox

viper · May 10, 2011

Not burried on this house. Floating in the breeze...

Even at half capacity, that is 700A. 50kva is 40kw which is 166A. Even at 125% max short duration draw, that is 208A. Even considering that everyone was only pulling 50A, that is still 350A which is WAY over the size of that transformer. What a screw job over here... Hopefully the squeaky wheel will get greased. As I sit here looking at a voltage that is only down by 1V right now... If it wold just stay that way!

Me Squzeee, that would be 208A cont and 260A at 125% peak. Either way, I fail to see how we are getting what we pay for.

RMeyers · May 11, 2011

PoCo's operate under different rules then we do, wiring is sized different & transformers are sized close to auctual load.

JST · May 11, 2011

That is standard Powerco practice, you are NOT "getting screwed".

Residential is INTERMITTENT DUTY and "diversity" comes into play as well, not everyone will be drawing max power.

If all of you DO, and keep it up for a while, there will be a pole fire, and your power will be out for a day or two while they get around to replacing the transformer.

Just another day at the powerco, that very seldom happens. Actually, in general the overload pops before there is a pole fire. if it happens enough, they have to upgrade a bit.

BTW, you probably are getting as much if not MORE drop through the transformer as the wires..... the "impedance" of small transformers as on your pole can be 5%, meaning a 5% drop at nominal full power. Add drop in wires, and a low distribution voltage, and you can get 10% drop easily.

Especially if your actual local draw is OVER the nominal for the transformer.

viper · May 11, 2011

yeah, I realize they do not want to properly size the transformer for every application. I still cannot get an answer as to how much a transformer costs to stay live on a pole but I am sure when you multiply that for the thousands of transformers, it gets pricy.

Our POCO is actually very good and responds to my calls within minutes. I have no doubt if I take out a Xformer, they will replace it quickly and already have though I am not sure what was up there previously. If I could get my sag corrected a bit, I would not care too much about that transformer size. Wring it neck and see what happens.

I have to figure that every home WILL pull 30-50A in the early evening in the summer. AC load plus some range loads are enough to get there. Not real sure how that can handles it, but it has for many years, even with my loads.

I honestly hope they find that they can upgrade some wire here and there and fix it. I am not trying to get them to build me a whole new service, just correct some voltage issues. I visited the parents last night and ran theirs through the same tests, oven, stove top, AC, dryer, microwave. Their voltage did not drop at all, mine would be at 108-110V.

viper · May 18, 2011

Decision was made my POCO to install me my own transformer for my place. This will reduce my line distance from 400ft to 75ft with no chance of other homes causing problems. OUTSTANDING!

SND · May 20, 2011

that's great, Did they mention the size of the transformer they'll put you on?

My transformer is about 30-40' away, I get 400amp 248V, but I tried to read the numbers off of it and google it(Siemens transformer) I can't find a darn thing about them. It's got a 25, and below that a 14.4 I think, and a H2 on the other side, none of which makes sense for 400amps(360amp continuous) service. No power issues here, just curious. But I have a neighbor a few houses up that is on regular 200amp about 220' from the line, I don't even know where the transformer is and when his heat pump kicks on all the lights dim quite a lot, it would annoy me quite a bit.

gpkull · May 20, 2011

SND around here a 25 is 25 kva and on a 40' run thats pretty hot. i see 247 to 252. we are on a 25 kva 5 houses but not far (1/8 mile) from a substation. hot all the time but when the trees start shakin we are last to get restored due to access to our hot set up

Voltage sag and the power company

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