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I want two two post lifts, one 80 gallon compressor, 15,000 watt heater and outlets for normal use and lights.

What size breaker box do I need and what gauge wire do I need if is 80 to 100 feet away from my main panel?

isherwood
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Supu
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    Good chance your main panel/service cannot not handle that much extra power needs. You are looking at(guessing) ~150 to 180 amps extra(or more). – crip659 Dec 01 '23 at 19:20
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    Swap the heater for a minisplit - less power for more heat. For the rest of your loads, you'll need a load calculation, and you haven't provided specific electrical loading of the various named devices other than the heater. Also need the square footage of the garage as part of the calculation for the lighting and general outlet loads. Other than that, drop garage sub-panel (or subpanel also barn or shop instead of garage) into the search box, it's a common question at the vague level. Load calculation would be another good search term for you. – Ecnerwal Dec 01 '23 at 19:25
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    Useful data: My 2-post lift has a 2HP 208/230V hydraulic pump motor and required a 25A breaker according to the instructions. My 80gal compressor with 7.5HP 208/230V motor draws 32 amps when running and required a 60A breaker according to the instructions. – MTA Dec 01 '23 at 19:40
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    A minisplit will also give you air conditioning in the summer, which is a bonus in many parts of the world. – FreeMan Dec 01 '23 at 19:44
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    Useful for a ball-park, @MTA, but the ones Supu is planning to use might be different, of course. Does tend to support the "likely too much without a service upgrade at the house, or a new service drop at the garage" theory, though. – Ecnerwal Dec 01 '23 at 19:58
  • Basically the process is: Figure out your total load. Then figure out how much capacity is available in the main panel. If your new load is less than what is available, then we can go on to figure out wire size. Panel size is the trivial part - you can get a cheap "main" 200A panel and use it for pretty much anything, even if your load and feed is 60A. – manassehkatz-Moving 2 Codidact Dec 01 '23 at 20:02

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The usual conversation here is someone wants a 6000 watt electric heater and we kind of nudge them in the direction of a heat pump because it'll be a big cost savings over the life of the unit. But I know the heat pump will cost more to buy and install than the space heater, so I don't get my hopes up.

Your situation is completely different.

A 15,000 watt heater will need 80 amps of power provisioned to it. Eighty amps.

It's a hard HVAC load, which means it'll come in at 100% on your NEC 220.82 Service Load Calculation. There is no way you're talking your way out of a service upgrade on this one, unless you "do the impossible" with an energy management system. Either way, provisioning this will cost a fortune. And on top of it, when it's all in, you'll be paying $2 per hour (in 2019 prices) to run the thing. And it won't give you air conditioning; you'll have to spend again to buy that. And an air conditioner is a heat pump, so you're buying a heat pump after all, just a crappy one without a reversing valve.

No, this is not financially rational. It won't even give you

A 15,000 watt heater will come in at about 50,000 BTU. So that's a Williams/Empire double sided wall furnace. That run on propane would be slightly cheaper than electricity right now, and 1/3 the cost on natural gas right now.

But if you want cheaper operating cost than natural gas, and air conditioning as part of the deal, all the wind's blowing toward heat pumps. "I'm in Chicago" so is Alec from Technology Connections, and did a case study on the hellish 2019 Chicago winter in video 2 of this series. The Asian style heat pumps are sensibly priced and have no trouble with the cold. To get the BTUs, I would put in 3 cheap ones, rather than one large "heat pump to rule them all".

Harper - Reinstate Monica
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