We are getting going building our house/shop/workspace building. Its large so we are going with a 600amp main panel and a few sub panels - one for the business end and a few in the residence and a 100amp for the pump house and outbuilding. The building will have an elevator, so we are doing 3 phase. There are a million panels out there and we just aren't sure what we really need. Do we need a main 600amp meter and breaker panel, then 3 200 amp breaker panels before we event separate into the subpanels?? I'm seeing meters for 600amp but they have like 5 meters on them and we just need 1. Have watched more electrical panel videos than any non-electrican should to no avail on what exactly we should buy, which is what I need help with. Since we are doing 3 phase, do all the sub-panels also need to be 3 phase or just the one thats carrying the big load with the elevator?

We have some electrician friends that will come in from out of state to help with wiring the house and subpanels and everything, but it sounds like shopping for the main panels is not their typical job so they haven't been much help. What all do we need? My husband had bought a meter not realizing he bought a 200amp meter which doesn't help us with the main panel :). However, I think we will use it for the subpanel going to the business part of the building so we can properly split the electric bill and some day if we convert it into a rental apartment it will be measured.

So. I need to shop. I need to get the different sized wire for running everything from the transformer to the main panel, from the main to the house utility closet that will run through the underground tubing, and panels and breakers, the works. My husband said he's fine getting it all hooked up if I can just get it bought (about as helpful as the other electricians!). So, If you were setting up this kind of service, what would you have on your shopping list and where to buy from?? The building where all the exterior panels will be going is being finished now so we can get the electrical attached and hooked up and finally get power out there. Thanks in advance

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    Have you talked with the local power company yet? Do they even offer 600 amp or three phase power? The local power will say what panels they approve for use and then your choice will be narrowed down to what they say.
    – crip659
    Mar 25, 2023 at 18:13
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    Shopping questions, in terms of recommendations for specific equipment, are usually considered off-topic. General requirements are on topic, but spec'ing the design for an entire house is sorta unfocused. Do you have specific questions?
    – keshlam
    Mar 25, 2023 at 18:58
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    I recommend that this particular aspect of your construction project be handled by someone who does not need to come here with high level questions. You can come here for help to clarify or refine details of their plan. Note that with 3-phase service, if that's even available, you'll have 208/120 service, and you need to ensure that all your high load equipment (air conditioning, clothes dryer, etc) are either designed for 208 or, more likely, will at least work with reduced performance at 208.
    – jay613
    Mar 25, 2023 at 18:59
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    @jay613 3ph is not always necessarily 208v. My church has 3ph and it's 240/120v. I know this because when I supervised a large water heater replacement, I specifically told him while we had 3ph, it 240v. ....well he bought a 208v, installed it and blew out all the breakers. upgraded to 240v elements and it worked fine. Mar 25, 2023 at 19:59
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    Who is your electric utility? Also, have you NEC Article 220 run load calculations yet, or are you just buttuming you'll need 600A service? Last but not least: 1) what are the square footages of the a) workspace, b) shop (if separate from the workspace) and c) house?, 2) what is this workspace and/or shop space going to be used for? Craftwork of some sort such as wood, metal, or glass? Food or drinkmaking of some flavor? Or some other sort of business venture?, and 3) how tall is the building with the elevator in it, both in feet and stories? Mar 25, 2023 at 21:02

1 Answer 1


You're thinking about these things much too late, and now, you'll be paying.

Your first stop is to talk to the power company about what kinds of power they are willing to offer you, and at what price. You'll need to make a choice, but if you're talking 3-phase you get Hobson's Choice - they decide which varietal of 3-phase you get and that's that. You will need your own transformers to adapt that to the varietal you need. Once we needed 480V "delta" and they refused to install a delta transformer; they only install "wye" as a matter of policy. We had to buy a wye/delta transformer.

Also, they're not going to deliver 2 types of power to your building. They don't do that and NEC doesn't allow it. So if you take 3-phase, you'll be on your own to create 120/208/240V from that. So more transformers and careful panel arrangement. They will expect even phase loading.

Next, you talk about the AHJ (permit issuer/inspector) about what they will permit. That also is a show-stopper. While you're there, you'll need to have the "How much of this can we DIY?" conversation. They're not going to let you DIY 3-phase or anything over 120V to ground. Also as a separate matter, anything involving refrigerants cannot be DIYed as a rule (certain refrigerants are exempt).

Now there's been a meeting of the minds among your ambitions, your wallet, what the power company will provide, and what the AHJ will permit... you get AHJ sign-off and go to the power company and order that. And if it's 3-phase, you may wait awhile. There are long lead times on power distribution equipment for some reason.

Only here do we answer your question. The power company will provide a list of acceptable hardware for the option you have chosen, and again, you get Hobson's Choice.

The AHJ will also be deciding to what extent you will be able to DIY this work. As a rule, they don't allow DIY on 3-phase. A licensed electrician must do it, or at least closely oversee any work you do. They will be signing off on it, and their insurance and license will be on the line. The most you could hope for is lay empty conduits so they can just pull the wires and go, but they'd only accept that if they could eyeball the conduit work i.e. before drywall went up.

I'm not clear on why you are saying you need 3-phase. If you're picking that "because it sounds nice-and-BIG and we like BIG" then that may be misguided. If you have chosen some random product that requires 3-phase, then choose a different product, or use a phase converter. Putting a single-phase motor on a piece of machinery isn't that hard - the factory can handle it.

The other thing is that it sounds like you are price-aware. 3-phase is the polar opposite of affordable. Typically rural distribution only brings 2 phases of high voltage the last couple of miles, since all the transformers on it are 120/240V. So you may need to pay to have that third HV phase added to your branch. All that can fly up into mid-5-digits real quick, and solar/battery (with proper design) can actually become competitive - "cut the big cord".

In that "wye/delta transformer" incident, the nonsense was so expensive that I would've cut the big cord if I had to do it today. Today, battery is less than 25 cents a watt-hour at scale.

  • 3-phase was stated as a requirement for an elevator. While that may be required for many elevators, I know there are plenty of ordinary (not mansions) houses with elevators and also retrofit residential elevators available, and I highly doubt those require 3-phase. Mar 26, 2023 at 1:07
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    @manassehkatz well, we have to assess the overall skill/experience level of askers before treating all the things they claim as "absolute truth". I agree mobility elevators and stairclimbers exist for the benefit of seniors/disabled; however none of them require 3-phase supply because 99.999% of their customers do not have 3-phase and they'd like to sell more than 2 a year :) OP sits in a contradiction of wanting a commercial elevator, yet not the financial wherewithal to leave all this to a pro. This is also one spouse asking about the other spouse's plan, so "Chinese whispers" may occur. Mar 26, 2023 at 18:34

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