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Old 01-04-2011, 03:55 PM   #16
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dimming lights from large geothermal heat pump


I got the poco putting the monitor back on later this week and leaving it on so we can demonstrate the problem. They only monitored for a few days where it was 60 degrees out and we didnt even have a chance to run the heat pump but maybe a little bit in low during the night when nothing else was on.

Now if I could only find a decent electrician around here... really wish I could just drop a chunk of change and have it fixed, but lately, the contractors I get out here seem to just be a waste of money. Half of me just wants to spend a little more to get a meter and debug it myself in my non existant free time rather than waste time/money on another crappy contractor.

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Old 01-04-2011, 04:28 PM   #17
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If you write a large enough check the poco will do anything you'd like. If you're so concerned have them install a new, separate transformer on your property.
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Old 01-04-2011, 05:01 PM   #18
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Originally Posted by atuel View Post
I got the poco putting the monitor back on later this week and leaving it on so we can demonstrate the problem. They only monitored for a few days where it was 60 degrees out and we didnt even have a chance to run the heat pump but maybe a little bit in low during the night when nothing else was on.

Now if I could only find a decent electrician around here... really wish I could just drop a chunk of change and have it fixed, but lately, the contractors I get out here seem to just be a waste of money. Half of me just wants to spend a little more to get a meter and debug it myself in my non existant free time rather than waste time/money on another crappy contractor.
What would you like fixed, specifically?
What if there is nothing to be fixed? What meter would you propose to use to "debug" this yourself?

An electrician cannot do anything for you, unless the problem is in the house or with the service. This house seems very new so I doubt there is very much wrong there.

If the POCO said there is only a 3-5V drop then that's that. Did the heat pump come on that night? If it did then that is a reading point for them. Doesn't matter if it was warm or not. If it came on it came on.

Where are you getting this ambiguous 60% number from? I HIGHLY doubt anything is dimming 40%.

I don't want to sound rude, but you are not going to stop asking until you get the answer you want to hear. This is a common phenomenon on forums like this. There is a very real chance that answer is not coming.
I understand that you are upset about something, but sometimes that something is not anything.
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Old 01-04-2011, 05:14 PM   #19
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If you write a large enough check the poco will do anything you'd like. If you're so concerned have them install a new, separate transformer on your property.
That might be a bit drastic at this point. So far you have told me that NEC doesnt apply and its expected/live with it. And now an extreme to the other end with dedicated everything. This is not really helping me.

I'm getting monitoring put in to help diagnose... poco shouldnt have pulled it so soon last time and should have configured it to get the data we find ourselves asking for now. So right now I'm leaning to the supply being an issue, but I could be wrong as its really just barely an indication at this point.

I'd really like to hear from people that have "stretched" the limits of 4/0 to 400A and either had or not had issues. Or others that always do 4/0 paralleled or use larger cable and never had an issue. Or maybe others that have used split 200A panels like I have instead of a single 400A and gotten burned on it. Really, any related stories/situations with heavy loads like this or similar issues.
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Old 01-04-2011, 05:21 PM   #20
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I said the NEC does not apply to the poco installation. You could have an electrician install larger conductors from the meter to your panels but I doubt if that will help much.
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Old 01-04-2011, 05:22 PM   #21
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A single 400A panel in a residence is an absolute rarity. Your dual 200A panels is the norm.

Bottom line is what is the voltage drop reading? Regardless of what size wire and what panels you have.

If they are coming out again this will confirm or deny the last reading. I'd wait and see what that shows.
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Old 01-04-2011, 05:32 PM   #22
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What would you like fixed, specifically?
What if there is nothing to be fixed? What meter would you propose to use to "debug" this yourself?

An electrician cannot do anything for you, unless the problem is in the house or with the service. This house seems very new so I doubt there is very much wrong there.

If the POCO said there is only a 3-5V drop then that's that. Did the heat pump come on that night? If it did then that is a reading point for them. Doesn't matter if it was warm or not. If it came on it came on.

Where are you getting this ambiguous 60% number from? I HIGHLY doubt anything is dimming 40%.

I don't want to sound rude, but you are not going to stop asking until you get the answer you want to hear. This is a common phenomenon on forums like this. There is a very real chance that answer is not coming.
I understand that you are upset about something, but sometimes that something is not anything.

If theres nothing to be fixed, then that's it, but we're not there yet. I'd like the significant dimming issue resolved. House was built in the late 80s.

During the monitoring period, no, the heat pump did not really come on. I did not notice dramatic dimming of the lights. In fact, we actually had the windows open because it was 73 in the house when thermostat was set to 68. The heat pump has many stages for energy efficiency and It was not cold enough to get it to kick into "high" like it was when I first called on it.

The dimming figure is subjective to my own senses, but my living room lights have a dimmer that I can slide to what I think matches and that was 60%. Its just an attempt to indicate to those who cant see it what it is doing.... maybe its only 70%... not a hard measurement.

I may not get an answer here, but why not ask and try to understand and possibly find out someone else is/was in the same boat before.
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Old 01-04-2011, 05:37 PM   #23
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During the monitoring period, no, the heat pump did not really come on. I did not notice dramatic dimming of the lights. In fact, we actually had the windows open because it was 73 in the house when thermostat was set to 68. The heat pump has many stages for energy efficiency and It was not cold enough to get it to kick into "high" like it was when I first called on it.
Well this is different than what you said before.

Quote:
They only monitored for a few days where it was 60 degrees out and we didnt even have a chance to run the heat pump but maybe a little bit in low during the night when nothing else was on.
Why not crank the t-stat to 80 deg for 10 or 15 minutes to be SURE it gets into high?
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Old 01-04-2011, 06:51 PM   #24
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Originally Posted by Speedy Petey View Post
A single 400A panel in a residence is an absolute rarity. Your dual 200A panels is the norm.

Bottom line is what is the voltage drop reading? Regardless of what size wire and what panels you have.

If they are coming out again this will confirm or deny the last reading. I'd wait and see what that shows.
Thank you... that is helpful to know 400A panels are not normal.

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Well this is different than what you said before.



Why not crank the t-stat to 80 deg for 10 or 15 minutes to be SURE it gets into high?

Well, two reasons...

I was trying not to skew the original results. Poco originally said they'd keep it on there a week and would call before coming out to fetch it, so I was waiting for the colder weather that we're now back in. Unfortunately, they came out and got it only after a couple days and did not call so I couldnt tell them it had been off for the several days of high temperature weather. Poco also forgot to configure their monitor to record current along with the voltage, so still left speculating on what I'm actually drawing. They assure me they will configure it this time. They also assure me they'll leave it on there for a week this time.

Other reason was its not quite as easy as turning up the tstat as I have this too damn smart for its own good zone controller with multiple tstats non here that trys to prevent it from ever getting into high. It likes to play games with enabling one zone and seeing how it affects the other zones and running the fan only to circulate air around from other sources (stove, dryer, etc). Under the right continued failures to maintain temperature, it'll give up with the games for a while and kick it in high right away for a while before it goes back to playing games again.

So I was being a little ethical and a little lazy. I can try to force it and probably will at some point this time around. Maybe just leave the windows open so it cant maintain temperature.

Last edited by atuel; 01-04-2011 at 07:57 PM.
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Old 01-06-2011, 04:43 PM   #25
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Ateul, the power company uses a different set of rules for sizing cables up to your meter. From that point into the house, sizing is based on the NEC residential code, and it sounds like at least your wire sizes are fine. I doubt the problem is on the neutral, since most heat pumps run on 240V as has already been indicated.

If you're really getting a 60% drop in your lights, and are getting equipment failure, but your POCO has only measured a voltage drop of a few volts back at the transformer, then you could have a problem anywhere from that point to the loadcenter that feeds the heatpump, but the problem might also be with the POCO.

You might have a licenced electrician who knows how to use a scope or a true RMS multimeter with a max/min capture feature try the following:
During heat pump startup, measure max/min voltage from line to line, and each line to neutral at each of the following points:
1) At the heat pump (the heatpump end of the #4 Cu cable).
2) At the heat pump circuit breaker (the loadcenter end of the the #4 Cu cable).
3) At another 240V circuit breaker in the same loadcenter (such as your dryer or stove. Make sure it's not running when you're measuring).
4) At a 240V circuit breaker in your neighbor's loadcenter.
The voltage drop should be the most for #1, and least for #3. And if #3 is more than a few volts sag for a second or two, then your problem is probably upstream of the loadcenter. It could be as simple as the loadcenter wires haven't been properly torqued into their lugs-- which is potentially a very dangerous situation. But my guess is that it is a POCO problem.
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Old 01-07-2011, 08:28 AM   #26
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Ateul, the power company uses a different set of rules for sizing cables up to your meter. From that point into the house, sizing is based on the NEC residential code, and it sounds like at least your wire sizes are fine. I doubt the problem is on the neutral, since most heat pumps run on 240V as has already been indicated.

If you're really getting a 60% drop in your lights, and are getting equipment failure, but your POCO has only measured a voltage drop of a few volts back at the transformer, then you could have a problem anywhere from that point to the loadcenter that feeds the heatpump, but the problem might also be with the POCO.

You might have a licenced electrician who knows how to use a scope or a true RMS multimeter with a max/min capture feature try the following:
During heat pump startup, measure max/min voltage from line to line, and each line to neutral at each of the following points:
1) At the heat pump (the heatpump end of the #4 Cu cable).
2) At the heat pump circuit breaker (the loadcenter end of the the #4 Cu cable).
3) At another 240V circuit breaker in the same loadcenter (such as your dryer or stove. Make sure it's not running when you're measuring).
4) At a 240V circuit breaker in your neighbor's loadcenter.
The voltage drop should be the most for #1, and least for #3. And if #3 is more than a few volts sag for a second or two, then your problem is probably upstream of the loadcenter. It could be as simple as the loadcenter wires haven't been properly torqued into their lugs-- which is potentially a very dangerous situation. But my guess is that it is a POCO problem.
We didnt capture a significant drop in the poco monitoring the first time since it was a bit of a warm stream where we didnt have the heat pump on. I've currently got the poco monitoring it for a week (ending tues or wed next week). They are actually monitoring it at the meter vs out at the transformer. They've got a box made by PMI duct taped to the top of my meter box with cables going inside the meter box. Should they be monitoring out at the transformer instead?
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Old 01-07-2011, 09:36 AM   #27
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Just called the utilities (medium sized town co-op) back and they confirmed its 4/0 triplex direct burial cable not paralleled (with a 2/0 neutral) from transformer to a platform that services both my neighbor and I. Neighbor has 1/0 service lines and I have 4/0 with 2/0 neutral. Its all underground including the feed to the transformer. No above ground cables.
Has your neighbor said anything about their lights dimming?
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Old 01-07-2011, 10:15 AM   #28
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I'd really like to hear from people that have "stretched" the limits of 4/0 to 400A and either had or not had issues. Or others that always do 4/0 paralleled or use larger cable and never had an issue. Or maybe others that have used split 200A panels like I have instead of a single 400A and gotten burned on it. Really, any related stories/situations with heavy loads like this or similar issues.
I have 400 amp service (split to two 200 amp panels)

The utility put in 4/0 cabling IIRC.

I have a 5 ton HP and when it kicks into defrost with the 20KW backup heat kicking in, the lights on its subpanel in the basement dim briefly. (It is annoying) but anything else in the house which ties into one of the two 200 amp panels are fine.

The basement panel is a 100 amp sub panel fed by 2/0 copper.

We do experience a brief dimming when the HP compressor engages, I was told I could install a start capcitor that should be able to provide the in-rush current the compressor needs on startup....reducing the dimming issue, and theoretically extending the life of the compressor.

When I upgraded to 400 amp service, I questioned the poco engineer about the size of cable ran to the meter and even posted on here (would have to find the post) and was told, since they dont have to abide by NEC rules, they can use whatever they want.

The highest amp pull I have seen on the monitoring system I have, was around 210 amps.

This was with the ovens going, microwave, tvs, lights, water heater, Heat pump, backup heat and hot tub running. (holiday with family over)
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Old 01-07-2011, 10:20 AM   #29
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Has your neighbor said anything about their lights dimming?
I have not checked with them yet as I'm not positive on which neighbor yet as poco didnt tell me which one.

I'm also wondering if they are not referring to the the barn on the other side of my property that has its own meter separate from my house. Only thing weird is the meters are on separate sides of my property on opposite sides of my house and driveway and the service lines dont intersect except at the transformer. I thought the poco said the shared line with my house is 1/0 off the 4/0 main, but also thought they said my barn is fed with 2/0.

The neighbor to the side where the service line for my house runs by has what I'd guess is around a 3000 sq ft house like mine, so not sure how he might be able to get by with such a smaller service line. Its an older guy that lives there by himself and does not spend much time at home. I havent seen the him for almost a month now, so not sure where he is.
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Old 01-07-2011, 10:31 AM   #30
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We didnt capture a significant drop in the poco monitoring the first time since it was a bit of a warm stream where we didnt have the heat pump on. I've currently got the poco monitoring it for a week (ending tues or wed next week). They are actually monitoring it at the meter vs out at the transformer. They've got a box made by PMI duct taped to the top of my meter box with cables going inside the meter box. Should they be monitoring out at the transformer instead?
I think someone needs to be monitoring minimum voltage in the house at the loadcenter in addition to what the POCO is doing out at the meter to make sure you don't have an internal wiring problem. It doesn't need to be all the time, just get minimums when the heatpump turns on.

The more I think about it, if you've got a weak cable connection at the loadcenter, you want that known and fixed right away!

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