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Thread: Electrical service size

  1. #1
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    Electrical service size

    I am working on getting my service for the new shop upgraded and am going back and forth on what size I need. The service will provide power to my mostly one man sometime 2 man shop, my wife's glass fusing studio, a small store front, and a 4 bedroom house. My largest tool is a 20hp wide belt sander. I also have several more 7.5hp tools. My wife's largest kiln will draw about 90 amps. I was originally going to go with a 400 amp service however you can only constantly draw 320 amps for a standard 400 anp service so now im looking at a 600 amp service but the cost is almost double. What size service are other guys running?

  2. #2
    You need 3 phase power. Consult an electrician.

  3. #3
    Quote Originally Posted by Mitch schiffer View Post
    I am working on getting my service for the new shop upgraded and am going back and forth on what size I need. The service will provide power to my mostly one man sometime 2 man shop, my wife's glass fusing studio, a small store front, and a 4 bedroom house. My largest tool is a 20hp wide belt sander. I also have several more 7.5hp tools. My wife's largest kiln will draw about 90 amps. I was originally going to go with a 400 amp service however you can only constantly draw 320 amps for a standard 400 anp service so now im looking at a 600 amp service but the cost is almost double. What size service are other guys running?
    It will depend on how much you want to run at the same time and what the other loads are.

    Your power company will probably want to do a load justification, where you document whats going to be on the service, but you can do it yourself:

    1.The size of the house and shop are going to factor in through HVAC load, big draws for the condensors, so how many and whats the tonnage. They can be 50A ea. Look for other big loads, such as electric water heater, electric dryer etc.
    2. Are you going to have a pool? You can count ~50a for that.
    3. You mention the "largest" kiln, but what is the total draw of all the Kiln's she wants to run at the same time?
    4. For your shop, you can probably count up the load from your dust collector, and 27.5HP (the Wide belt + one 7.5hp tool) to give you a good idea what max load would be with two men.

    I don't think it's unreasonable to fit that into 320a but calculate it out.

    To answer your specific question, I have 400a (320a nominal) and we have a lot on it. It comes down to not everything running at the same time usually. In other-words, the overbooking factor for load. There's probably an industry standard calculation for this you can find or someone on SMC knows.

  4. #4
    I would go with 1,200 amp service and be done with it. I would think 320amp service would not be enough.

  5. #5
    Join Date
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    Hi Mitch
    I did the calculations when planning for a generator. That was easier for my application since we have an ordinary house to support.

    You need to make a list of the bigger loads. It's going to make a difference if you have electric heat, electric water heater etc. For each big load list voltage and watts (amps without voltage is not enough). For that wide belt, try to get an amp load when sanding. Chances are it's well under the FLA.

    In the future you may need an electric car hookup, which could be your biggest load. Possibly it could interlocked with the sander or electric heat if 320 amps causes problems.
    Last edited by Tom Bender; 01-23-2022 at 8:28 AM.

  6. #6
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    I will make a suggestion that you put the house on a separate meter from the shop/business. If you want to mix the money, the can both hit the same bill in many areas (check with your power company about that for where you live) or be separately billed. Separate meters/drops means you can focus only on the shop/business needs on that side and without the house involved, the standard 400 amp service may work for you. I agree that an analysis needs to be done to determine concurrent load.

    I am going to put my future shop building on a separate meter here at our new property, but since in my case it's not a business, they will point to the same bill. Our power company does have a $10 monthly charge for that privilege. The house will be on a whole house generator shortly and logistically relative to where the shop building will go, it will be far more efficient and less costly to put in the separate drop from the power provider.
    Last edited by Jim Becker; 01-23-2022 at 9:14 AM.
    --

    The most expensive tool is the one you buy "cheaply" and often...

  7. #7
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    New Hill, NC
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    What Jim said.

    Depending on the size of the house, I would bring in a 200a single phase service (or larger if needed).

    For the shop, a 400a 480v three phase service should give you everything that you’d ever need.

    What voltage is the 90a draw for your wife’s kilns calculated at?

  8. #8
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    Quote Originally Posted by Robert Engel View Post
    You need 3 phase power. Consult an electrician.
    The cost to install 3 phase was 114k$ that is out of my budget.

  9. #9
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    I should maybe clarify a bit. This is all in one building. It is a old grocery store the is about 8k square feet. I javelin been consulting with several electricians and they all seem to have a different opinion. I did pay a electrician to do a load calculation for my shop and my wife's studio which cane to 380 amps. The calculation does not include the house or storefront. I have the choice of propane for the water heaters, stoves, and dryer. I am hoping to get some real world experience from other with similar size equipment and what they have for a service. I have not ruled out having more then one meter however it seems that with supply chain shortages it is very difficult to get the meter base I would need to have separate meters over 200 amps due to my electrical service provider requiring a certain style. This has been a very frustrating process I have been back and forth with 3 different electricians for about 8 months now and I'm no closer to having the panels installed.

  10. #10
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    Modesto, CA, USA
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    Look into NG or propane for the kilns and heat. I would be surprised if it did not pay for the conversion very quickly. Do they even make floor sitting kilns electric?
    Bill D

  11. #11
    Can't answer any questions about kilns or that other stuff but agree re. Jim's comments about putting the shop on a separate panel if at all possible. Regarding how many amps, I would go for 600 if you could. I seem to hear "We don't have enough amps" on a pretty regular basis from smaller shops once we start talking about new equipment. New-construction is the ideal time. Good luck with your project.

    Erik
    Ex-SCM and Felder rep

  12. #12
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    Quote Originally Posted by Bill Dufour View Post
    Do they even make floor sitting kilns electric?
    Bill D
    Yes, we have over 13 in the school district I work for in various buildings. Three phase and single phase all ducted to the outside

  13. #13
    That would be up to the PoCo, there are limits on single phase service sizes.

  14. #14
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    Quote Originally Posted by Rollie Meyers View Post
    That would be up to the PoCo, there are limits on single phase service sizes.
    This is a mixed use commercial building so the limit for services size really isn't a issue.

  15. #15
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    Quote Originally Posted by Ron Selzer View Post
    Yes, we have over 13 in the school district I work for in various buildings. Three phase and single phase all ducted to the outside

    Schools have kilns? Surely not ordinary high schools, I thought anything resembling shop class went out decades ago.

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