400 amp service


Hey group,
I'm contemplating going to Geo Thermal heat, I've talked to a couple different installers and they say that I need 400 amp service to do this. this would be split into 2 200 amp boxes, one for the geo and accessories, (which qualify for a lower rate) and 1 for the rest of the house.
currently I have 2 meters on the house 1st is a 150 amp service and the second is an interruptible service meter for my AC unit. ( I am in SE Michigan, use DTE energy)
If I need to go to 400 amp service is it as simple as having both meters replaced with larger 200 amp units? or would new wire need to be pulled from the road? a quick call to DTE resulted in an
"I don't know, We've done geo therm before and never had to put in new wire, but, I don't know everything"
Dave
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Do you have a 6,000 sq. ft. home?
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Nope, but 50 for a compressor, 50 for aux heat 50 for hot water, on the geo side
then the other 200 for the rest of the house
it adds up quick
Dave
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On Mon, 5 Mar 2007 20:13:18 -0500, "Zephyr" <Someguy@an email address.com> wrote:

I'd hate to pay your electric bill......
YES, you need larger cable from the pole and all the way to the breaker box(s). Possibly a new transformer on the pole. Possibly new meter sockets, and definately new breaker boxes (or at least for the mains).
Are you sure you really need that much power? I live on a farm, and my whole farm has 400A service. There are two 200A mains. I dont even use one of those mains. Of course the former owners had some electric grain bin dryers and those things are big power users. I run the whole farm on 200A with plenty to spare.
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Read the original post! The second breaker box and meter is to isolate the heating from the rest of the electric load. It is not that uncommon (though not widely publicized) that you get a discount for electric for heating purposes. This LOWERS the electric bill. My b-i-l did this a few years ago and he is saving gobs of money on heating!

Maybe you should look into electic heat since you already have 2 boxes set up. You could save a bundle on yoru heating bills!
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Zephyr wrote:

50+50+500. Do the compressor and aux heat ever run at the same time? If not the load for those 2 is 50A. What is the 50A for hot water - is that derived from geo or simple resistance heat. Resistance electric hot water is commonly a 30A circuit. **What circuit rating does the manufacturer say is required - or max concurrent connected load? As others are indicating, 200A sounds way high.
Sounds like your house now runs off 150A separate from the existing A/C. Why increase that to 200A?
-- bud--
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perhaps your new heating unit has auxilliary electric heat or air conditioning and needs more electricity. maybe you also need to consider a natural gas generator for emergency hookup with an additional panel and auto disconnect. code determines how many drops per type of dewlling/structure. and you can't put in a service main panel any larger than the existing service wires. there is a hidden extra cost of each monthly meter charge in buffalo ny around $16 per month. as in buffalo, you have winter. in our climate be careful. if you underestimate for energy efficiency, estimates of btu's required to quickly reheat your home on a windchill day by many energy efficiency calculations could be too chilly for too long. these systems you may want to have control over could use lots of zoning and temperature sensors if you want to see how the system is working and to help pinpoint problems. at the very least i'd want monitoring temperature gauges and indicator lights for the running pumps. and show me underground water temp in and out, and home zone temp in and out.
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I guess that is the heart of the question I am asking, how can I tell if the service wires will accommodate the 400 amp service? does the fact that I have 2 meters right now give any indication to that info?
Dave
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On Mon, 5 Mar 2007 17:57:19 -0500, "Zephyr" <an address @ some place .com> wrote:

Are you going to use the Geo to heat you, or are you goint to heat the Geo?
If you need 400 amps, it sounds like the second. Seriously, I'm new to this, but how could something that needs so much electricity save you money? Or save the world anything? How many amps are needed for pure-electric heat?
Sorry, I can't answer your questions.
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The question to DTE is irrelevant that it is goethermal. The question to them is can you upgrade the service to 400 amps without changing the wiring? They for sure should be able to tell you this.
As an aside, do you think the geothermal system will really save you any money in the long run? What about when you factor in what sounds like a sizable hike to your electric bill?
If you do the geothermal, I would be interested to read about your experiences with it as it is an interesting technology.
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DTE offers a 50% reduced rate on electric for people with geo, as for saving money, the compressor is all that runs really, and so its not that big of a bill, I've had companies promise me up to 50% savings on a typical gas bill for a house my size (2100 SF) check out www.waterfurnace.com for more info
currently it looks like around $16,000 - $20,000 to get in though the contractors are pushing a 8.5 year payback if the ratio of gas to electric hold less if gas gets more expensive vs electric.
Dave
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Something is really off. Geothermal should use less energy than a standard heat pump for both heating and cooling. A 2100 sq foot house should use about 3 tons (36,000 BTU) in the mid atlantic region, maybe 4 tons in Michigan. A geothermal unit is not dependent on outside temp since it draws heat from a constant earth temperature. Even if the electric service is sized for emergency resistance heat the amp ratings seem very high. Might want to check some geo mfgr websites for consumption.

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Something does not sound right. At the low end up front cost of $16,000 an 8.5 year payback means you would have a savings of $1182 per year or $156 per month. Couple that with a maximum expected savings of "up to 50%" on gas means that your gas bills now would have to average over $2300 per year or over $300 per month to make the figures you were given add up. I just don't see it but maybe I am missing something.
I had a good friend look into geothermal heat for his home but he decided against it saying it would be too expensive.
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You are ignoring rebates. Does your electric company offer any rebated for geo? Also, there are tax rebates from the federal govt for going geo. Check with your state also. Your price seems quite high. My son's is only going to be about $3000.
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On Mon, 5 Mar 2007 21:31:54 -0500, "Zephyr" <Someguy@an email address.com> wrote:

If you're pulling 50 amps for the compressor, and 50 amps for "aux" heat, then that's 100 amps * 220V or 22000 watts. Which would produce 74800 BTUs per hour. (Or, at 80%, around 60,000 BTUS) if you used it as straight electric-resistance heating.
What does your heating-load calculation say you actually need? 'cause that seems like it ought to be enough, all by itself, in which case, what the hell is the heat pump good for?
I mean, the whole point of geothermal is that it's supposed to use LESS electricity than electric resistance heating, right?
A 1 story 2100 sqft house that's 28 x 75' assume 2100 sqft ceiling at R36, (U~60) 1650 sqft of wall (10% window), @ R15 so (U~98) 10 % windows at R=1 so (U~165) =======Figure 20 below, outside, 72 in = 92 * 323 ~~ 30,000 BTUs/hr plus 2100 sqft floor, R5 ground temp 0 ~~ 30,000 BTUs...
--Goedjn
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On Mon, 5 Mar 2007 20:30:10 -0500, "Frank Ketchum"

I only know the basic principals of geo-thermal, but it seems to me that the whole thing is run with a couple pumps, and I imagine there are a few blower fans too. I cant see where any of these pumps or fans would require any more than a well pump or common furnace blower. A common well pump runs on a 20A breaker, and your could likely run two furnace blowers on a 15A breaker. IF there's 2 pumps, your max usage would be 55A. You are obviously disconnecting a standard furnace, so that will save a few amps. I agree, if this thing really needs 400A, I cant see the savings at all.
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Is this an underground service or overhead? The power companies rate their conductors differently than what is permitted in the code book. I know that one power company here in New Jersey has all of their service drops rated for a minimum of 320 amps. For larger services they would install larger conductors.
You didn't say if you plan to do this work yourself or have a contractor do it. A local electrician should know what is needed. If you are going to do the work yourself, I suggest that you get the paperwork started with your power company as soon as possible.
It sounds as though you only need to upgrade one of the services and leave the existing house service as is.
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Underground thats what makes me question, a new line underground is not cheap I'm sure

Given my questions, I figured that answer would be obvious. :) I'll definitly be having someone who knows what they are doing install it.

I was kinda hoping that, no need to pay for a new panel if the old works fine.
Dave
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You are wise to seek advice in this matter. IMHO, a 400 amp electric service for a 2100 SF house is just ridiculous. An HVAC contractor should be consulted only to calculate what size geothermal unit that you need. One should then give the electrical specifications for that unit to an electrical contractor, preferably one that is not associated with the HVAC contractor, and have them do an electrical service calculation, or do it yourself. Many electrical contractors who work with HVAC contractors are "yes people" and, since the HVAC contractor is buttering their bread, will install anything that the HVAC contractor asks for, in this case, a 400 amp electric service. RUN, don't walk, from anyone who tells you that you need a 400 amp electric service for a 2100 SF house!
The purpose of using a geothermal unit is to provide a high comfort level with a low energy cost. Installing a 400 amp service for an energy saving geothermal unit, IMHO, would be an oxymoron. Think about it. If one is indeed actually using the lion's share of a 400 amp service, one would probably need to get the place zoned for and open a restaurant to help pay the electric bill.

If you consult an electrical contractor, or the power co., I think you may find that installing a panel on the load side of the interruptible service meter large enough to accommodate the geo and it's accessories may be an option. I don't think that your "problem" is capacity, but more of one of physical spaces in the panel for the equipment. Discontinuing use of your existing heat/AC is going to free up spaces for the new equipment.
I saw your other posts, and I checked out your link to www.waterfurnace.com, but without knowing your existing electrical requirements and the model number of unit that you are considering (hopefully this was calculated by the HVAC contractors), including what size aux. heat in kW, one cannot make a electric service load calculation for you. There are plenty of people in this NG who can make the calculation for you, but we need more info from you, if you want to take the time: 1...SF of the house, OK, we know that, 2100 SF. 2...which appliances are currently gas and which appliances will remain gas once everything is said and done. 3...is your water going to be heated by the geothermal unit, and if so, what size is the backup (in kilowatts), if electric. 4...a list of your current electric equipment, such as whether or not you have (or going to have) an electric a water heater, disposal, dishwasher, dryer, washer, pumps, large fans, shop equipment, large motors, etc.
There is an online electric service calculator, but I can't remember where it's at. Maybe someone can post that link if you want to do it yourself. If you decide to do that, I would recommend that you get your calculation checked by a qualified person. There's plenty of help at: http://www.selfhelpandmore.com/index.htm
Electric services are not sized by adding up the breakers in the panel, they are based on well established demand factors, and only a properly made electric service calculation will give you the correct size electric service that you need. I seriously doubt that the HVAC contractors who you consulted even made an electric service calculation. I would also suspect that those same contractors didn't bother to make a calculation to size the geothermal unit either. One simply does not ask an electrical contractor to size an AC unit, nor ask an HVAC contractor to size an electric service, unless, of course, that person is licensed AND/OR qualified to do both.

A true 400 amp service will not only require larger wire, but most likely a larger conduit. Things can get expensive in a hurry....all for something that you most likely don't need.

It may not seem like much of a statement, but is says a lot. You want to keep the power co. in the loop. You may want to call them back and ask to speak to someone in the engineering dept. You may want to ask if they will come to your home and do an energy audit. You may want to call the geo unit manufacturer and ask them for the names of contractors in your area who have experience installing their equipment.
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