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This is for a 10 acre new residential lot in NW Washington. The transformer is 200ft away and this will be a new underground service to the home site. I'll be working on building the house myself over the next few years. The power company wanted to install temporary service but they say it can only be "temporary" for 1 year and they charge another $175 to hook up the permanent service. Additionally some parts of the temp service panel wouldn't be able to be reused for the permanent installation so there's a few hundred dollars in other wasted costs. At the location where I would put the temp service there will be a 30A RV hookup and a 20A circuit for some plugs. This is about 25 feet from the location of the eventual house. I would like to keep the RV hookup and plugs there after the house is done, so I thought why not make that the permanent location of the meter and main panel and run the house as a subpanel? My load calculations for the house alone using NEC 220 Part IV show that a 100A subpanel is more than adequate so I could use 2 AWG, XHHW-2 Al feeder wire from the main outdoor panel to a 100A subpanel in the house. The cost of 4 wires (2/2/2/6) are only $1.19/ft. The main outdoor panel would be 200A to accommodate the additional outside RV and plugs. The outdoor panel would also be able to handle future expansions like a shop or hot tub. I was planning on the Eaton MBE2040B200BTS 200A Meter Center for the permanent outdoor panel mounted on a 6x6 PT post or the side of a tiny shed with a roof overhang to protect it from rain. Are there any problems with this approach?

EDIT: I forgot to mention that an EUSERC approved panel is not required by my utility.

EDIT2: According to the comments below an EUSERC approved panel IS actually required by my utility.

  • Feed it 100A if you like, but use a 200A panel in the house (it's a breaker space issue, not an amperage issue - Also helps in the "if you/the next person ever choose to go bigger" line, but in that case be sure to at least use a generously sized conduit and contemplate using larger wires as well. – Ecnerwal May 26 at 18:44
  • I see no point in that. Install a 200 amp service the whole way saves a whole lot of work later 50 to 25 feet of the wire wont break the bank. – user101687 May 26 at 20:06
  • Hello and welcome , this is a question were it can be done many ways ..I will point out some topics for you,, and to think about... #1 Not knowing your area ,,you need to find out if you can do the work yourself permits ect.. If you can #2 You may want to talk to the power company , they may dictate where the meter has to be placed.. It may have to be close to the road.. Where i am from they supply one free pole And i think 100 feet of wire. also a 200 amp meter socket. Were you install a 200 amp breaker your main.it has to be weather proof . – user101687 May 26 at 20:39
  • I would put in 200 amp with 6 or 8 spares in it could have outlet up there .and motion lights . Drive way gate ect. With out knowing how far a run to house and total loads heat ac range ect ,,i would run 3 inch pvc sch 80 with expansion fitting ground must freeze movement plows panels apart along with 2 2 inch conduits for phone and cable or what ever i put a cap on the 2 inch and dont glue it drill a hole put tape on when phone wire in seal hole with caulking,, put them in while driveway being put in I would increase the wire due to the run code only sets the minimum standard. – user101687 May 26 at 21:22
  • i got cut of f this will get you to house. – user101687 May 26 at 22:27
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You have a few options here

Personally, I find many of the larger meter-loadcenter combinations to be wastes of space, especially in a remote-metered application like yours. You'll probably never use anywhere close to all the spaces in the MBE2040B200BTS with it mounted on the shed; furthermore, using that meter-main forecloses you from upgrading the feed to the house to 200A in the future, as a 200A breaker simply won't fit in the half-width loadcenter it provides.

With the considerations of a 3" incoming utility conduit, EUSERC approval, and provision for 200A to the house in the future in mind as we look for meter mains, this leaves us with roughly the following options:

  • If you can get decent pricing on it from your local supply house, the Milbank X5169-XTL-200 provides quite a bit of flexibility in this application. It has a 12-circuit interior with a backfed 200A main breaker, leaving 8 circuits and a set of feed-through lugs available for use, while providing a single-point-of-shutoff. In addition, it has an over/under layout, which is advantageous in that it can readily fit a separate 200A breaker for the main house, unlike single-column designs, while providing a 2-pole space for future expansion once the RV breakers are taken into account.
  • The B-Line U2M2RP provides a minimalist alternative here, with provisions for a 50A maximum "side" feed to the RV outlets alongside a 200A main breaker for the house. However, this does sacrifice the convenience of having a single main shutoff available to you, and also requires getting a good price from your supply house to be practical.
  • A more spacious option in the "no single main shutoff" vein is the Siemens MC1212L1200SED (also known as the Murray JA1212L1200SED). This also uses an "over/under" construction, allowing the use of a 200A breaker for the house feeder, and provides up to 3 2-pole spaces for expansion purposes as well as room for the RV breakers. Again, though, this requires getting good pricing through a supply house.
  • If none of the above work, and you are willing to sacrifice having a single main shutoff, then you can go with a Siemens MC0816B1200ESN. This provides an 8 space interior with a main breaker and feed-through lugs, as well as a parallel "side" feed maxing out at 50A for the shed and RV outlets, in a narrow form factor, and is available inexpensively from the usual suspects. The downside is that the remaining spaces will likely go mostly to waste in this case, but if nothing else is available, this will do.

With this, I would use a prebuilt RV outlet box such as a Midwest U041010 or equivalent. This provides a TT-30 receptacle and a 20A GFCI receptacle in a sturdy, weatherproof enclosure; you can also get a version (the U041CTL010) with a built-in panel and extra lugs to provide a feeder onward to the shed. You'll need to use a 30A and a 20A single pole breaker to provide power to the U041010 (there is also a U041, but that has a regular 20A receptacle and requires a 20A GFCI in the panel instead); if you go with the U041CTL010 instead, you can provide it with the biggest feeder your main panel will let you, up to 100A, and then use the loop-through lugs to feed the shed's panel from it, or just stick a one-pole THQL breaker in the spare slot provided and power the shed that way.

Fat conduit and fat aluminum are your friends here

You have the right idea by going with aluminum over copper for the feeder to the house; however, I would use conduit for this run instead of direct burial wire to save you the trouble of having to re-trench wires if you want to upgrade the house to 200A service. In your case, 2" Schedule 80 PVC makes good sense here, considering that you can get the run done with two wide sweeps (and a LB if the house's panel will be indoors), and that a set of 3 4/0 XHHW-2 aluminum current-carrying conductors with a 6AWG bare or insulated copper ground will fit comfortably inside it. Even if you only run a 100A feeder (2AWG hots+neutral with an 8AWG minimum ground, or a 2-2-4-6 mobile home feeder cable for that matter), you still will benefit from the oversized conduit making your pull far easier than it would in a minimum Code sized conduit. Beats having to call an electrician in with their truck of tools to rescue your over-optimistic pull job!

Go big or go home!

One other problem lurks in your plan so far: the size of panel you've chosen so far for the house. 16 spaces is a terribly small panel for anything beyond an outbuilding, considering that you can't use "double stuff" (tandem/quadplex/half-width) breakers for most residential circuits as nobody makes AFCIs in that form factor.

Instead, I would go with a 40-space or 42-space, 200A, main breaker panel for the house's main panel, as it's far cheaper to get the spaces now than to go through the labor of replacing the panel later. The main breaker is necessary because the meter-main is mounted on a separate structure (the shed), and the fact it is bigger than the feeder you want to run is of no concern to us, as all we want here is a way to turn the power on and off. This panel also will happily accommodate a future service upgrade to 200A, should you (or the next homeowner!) ever want that in the future.

If a 200A panel is absolutely out of the question for some reason, I would at least go with a 24-space or 30-space, 100A or 125A, main breaker panel instead of the rather cramped 16-space panel you are planning to use. The cost differential is peanuts here compared to the cost of adding those extra spaces down the road, still.

TORQUE ALL LUGS TO SPEC

There is one more point to raise here, and that is that you need to use an inch-pound torque wrench or torque screwdriver to torque all loadcenter and breaker lugs to the labeled torque values. This is a new Code requirement in 2017 NEC 110.14(D), and is a good idea even if your AHJ has not adopted it, as you really don't want your electrical system to develop a case of the loose lugnuts!

  • Thanks for the thoughtful and detailed answer!! I appreciate your concern that I may want to upgrade to a 200A house panel in the future, but this is my thought process: 1) It's a very mild climate and insulation requirements in Washingon are extreme so a 1.5-ton heat pump is all that is required by state energy code. 2) any future garage or shop loads can be run as feeders off the main panel and not go through the house sub-panel. 3) I'll be using propane for tankless hot water and cooking range with electric oven. Using the optional method for the house loads, I come up with only 64.1A! – Martin Vandepas May 27 at 18:42
  • @MartinVandepas -- when you say "garage or shop loads", are you talking about something attached to the house, or elsewhere on the property? Also, with the price of propane, you may wish to revisit your choice of water heater -- I ran the numbers on a propane tankless vs. a Sanden SanCO2 heat pump water heater (the latter being $4000) once, and with the propane prices I was able to find, the payback period for the SanCO2 was a mere 10 years.... – ThreePhaseEel May 27 at 18:46
  • Load Calculation: Lighting: 3VA*800sf=2400VA, Small Appliance: 2*1500VA=3000VA, Laundry: 1500VA, Dryer: 5000VA, Oven (propane range): 4200VA, Range Hood: 400VA, Dishwasher: 1400VA. This totals 17,900VA. 10kVA + .4*7,900VA=13,160VA. 1.5ton heat pump load is 2230VA so the grand total is 15390VA. 15,390VA/240V=64.1A – Martin Vandepas May 27 at 18:54
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    @MartinVandepas -- since the feeder breaker in the main panel protects the wire, the 200A breaker in the subpanel is merely a shutoff switch, so it can be any size >= 100A – ThreePhaseEel May 27 at 19:35
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    @MartinVandepas -- I have never seen a single question on this site complaining about someone having too much spaces, but plenty about panels stuffed to overflowing. Given the rather trivial difference in cost between a bare-minimum panel and an amply sized one...(maybe the difference between a night or two in and a night or two out), going big is pretty much a no-brainer :) – ThreePhaseEel May 29 at 23:08

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