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Thread: Two 240v 15 amp motors off single 240v 30 amp outlet?

  1. #1
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    Two 240v 15 amp motors off single 240v 30 amp outlet?

    First reason for the odd question. :-)
    Iím off grid and only have one big generator and only have one 240v 30 amp outlet.

    I need to setup to run two 240v 15 amp motor air compressors. Currently I run line from 240v 30 amp generator plug to sub panel with 240v 20 amp breaker and corresponding outlet that one compressor plugs into.

    I need a second compressor to run in tandem for more CFM. One possibility is setting up the second compressor to run off gas engine but would prefer not to have to do that.

    Sorry for the long descriptionÖ

    Question: can I run line from 240v 30 amp outlet to sub panel and split power to two 240v 15 amp plugs to run both compressors simultaneously?

    Hopefully this isnít a stupid question! :-)

    Cheers, Allen

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    Re: Two 240v 15 amp motors off single 240v 30 amp outlet?

    How many KW is the generator? Compressors pull a lot of amps on startup however I'll assume your already running one on the gennie. I doubt a 20 amp breaker will start a compressor but I may be wrong.
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    Re: Two 240v 15 amp motors off single 240v 30 amp outlet?

    Two ways of look at this.

    1) In construction the compressor will slow down the generator . This works like soft start.

    2) But powering a home 🏡 you not want the generator to slow more that 10% or 56 Hz or lights will dim and electronics will flicker.

    Note some generator may need slow blow fuses used to start a motor .
    The breakers on generators may flip off before the motor starts.

    Dave

    Quote Originally Posted by abosely View Post
    First reason for the odd question. :-)
    Iím off grid and only have one big generator and only have one 240v 30 amp outlet.

    I need to setup to run two 240v 15 amp motor air compressors. Currently I run line from 240v 30 amp generator plug to sub panel with 240v 20 amp breaker and corresponding outlet that one compressor plugs into.

    I need a second compressor to run in tandem for more CFM. One possibility is setting up the second compressor to run off gas engine but would prefer not to have to do that.

    Sorry for the long descriptionÖ

    Question: can I run line from 240v 30 amp outlet to sub panel and split power to two 240v 15 amp plugs to run both compressors simultaneously?

    Hopefully this isnít a stupid question! :-)

    Cheers, Allen

  4. #4
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    Re: Two 240v 15 amp motors off single 240v 30 amp outlet?

    It’s a 8000 running & 10,000 watt surge generator.
    The motor is 240v 15 amp supposed to run on a 240v 15 amp outlet.
    I got it new but with a blown motor, they tried to run it on 120v, fried the motor. :-)

    It’s a Kobalt 60 gallon 3.7hp 11.5 CFM at 90 psi.

    Got a 5hp motor of same brand & specs, 240v, 15 amp 3450 rpm because 3.7hp wasn’t available, same 240v, 15 amp.

    The generator runs the H190 fine and H210 when had it too.

    Cheers, Allen
    Last edited by abosely; 07-02-2022 at 08:12 PM.

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    Re: Two 240v 15 amp motors off single 240v 30 amp outlet?

    I think worst case is you'll just need to start one compressor and then start the 2nd one after the first one is already running.

    As mentioned, the start up amps is more than the running amps.
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    Re: Two 240v 15 amp motors off single 240v 30 amp outlet?

    Just put another breaker in the subpanel and wire in another plug for the second one.

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    Re: Two 240v 15 amp motors off single 240v 30 amp outlet?

    Ya, start the big one first and see if it works. If it didnt might consider a couple different things but with any new scheme a guy has to wonder,,,, what is it you are trying to do?

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    Re: Two 240v 15 amp motors off single 240v 30 amp outlet?

    If I had to do this regular would skip the genset and put engine drive on and maybe add some tank depending on what I was trying to do. I would sell the other stuff and go right down to the tool store and get me 13 hp engine drive.

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    Re: Two 240v 15 amp motors off single 240v 30 amp outlet?

    Quote Originally Posted by Sberry View Post
    If I had to do this regular would skip the genset and put engine drive on and maybe add some tank depending on what I was trying to do. I would sell the other stuff and go right down to the tool store and get me 13 hp engine drive.
    Sberry is rite. In the mean time tho, check this video out. At about 2:30 she explains something related to your question

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    Re: Two 240v 15 amp motors off single 240v 30 amp outlet?

    I watched a couple minutes of that but I see eventually relays and all but to a common electric service as long as they were wired opposite poles and maybe even not on heavy service,,, ha but so small it would all be irrelevent and most of time starting wouldnt be exact the same anyway, farting with stuff is what that amounts to. For the same money and a simple4 circuit 5 hp single stage econo can would be more practical. 240V balances the start load, doesnt require a manifold scheme all that crap.

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    Re: Two 240v 15 amp motors off single 240v 30 amp outlet?

    Jury rigged it'll work, if the generator is big enough. The proper way is to power a sub panel with the generator, then give each compressor a circuit. Remember, 2020 code calls for GFCI protection.
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    Re: Two 240v 15 amp motors off single 240v 30 amp outlet?

    Quote Originally Posted by Sberry View Post
    If I had to do this regular would skip the genset and put engine drive on and maybe add some tank depending on what I was trying to do. I would sell the other stuff and go right down to the tool store and get me 13 hp engine drive.
    With out a doubt, My 14hp Ingersoll Rand gives me 25cfm @175psi. Dedicating a generator to run 2 compressors makes less sense. Get the engine drive and free up the generator for other things instead of having it run at max output running 2 compressors.
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    Re: Two 240v 15 amp motors off single 240v 30 amp outlet?

    Agree with the others, get an engine drive compressor!
    Unless you're trying to run a manufacturing plant the compressor will run way less than
    lights, appliances and AC. Save the generator for them.

  17. #14
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    Re: Two 240v 15 amp motors off single 240v 30 amp outlet?

    The Freebird is in a different gear. I worried to tears over one of my setups and the shopping for this stuff just isnt what it is now. I would buy assembled unit on relatively economy unit if I was doing it today, I bought a comp and pieced the engine and all the controls on. The real upside of all of that is it is a learning experience, the curve is hi. I still remember even though I had good photo background the crap about an electronic and vid cams,,, today I am much better about translating and assessing the real risk so to speak over some equipment. I really couldnt find the size I wanted, the 14 like you have would have worked. All would have been different with different duty too. I am wishing it was portable now instead of fab on the truck but at the time it was totally enclosed and fit as well as being hi power and had the tanks saddled and under the truck.

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    Re: Two 240v 15 amp motors off single 240v 30 amp outlet?

    This is why I ask the op, sounds a little like a shot in the dark and some real assesment can make it more successful, today a lot cheaper is often easier. I wouldnt be above wiring another comp to the whole deal especially if I had it,,,, or was part of a real system or simply wanted or needed to,,, I get that but I wouldnt have headed to the store to get 4 pos I had to buy new and thats just the start, going to be a continuous process of relays, gonna wire a control box and start fooling with machines already been designed then figure out how to plumb it,,, all to make up for getting the right tool in the first place. Be different if there was real savings but that as a great idea,,, its not and someone outright should point out the deficiencies with that plan.
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    Last edited by Sberry; 3 Weeks Ago at 12:24 PM.

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  21. #16
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    Re: Two 240v 15 amp motors off single 240v 30 amp outlet?

    I might and would specifically tune it for economy, might be 11 hp, might need 14 and design for the cycle rate. They elude to the storage and need for adequate pump but storage lets it act as battery so time off the trigger is pumped so it doesnt pump full fast and shut off and then wait to come on till the pressure is lo,,,, we start, get the pump runing, blast of sand till it sags, then regroup and resume before shut off when its well charged and the pump is running and a guy aint got to hurry to get back especially if he has ran it down a little, know that if its down and I resume in 6 minutes or less the pump stays on and runs continuous.

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    Re: Two 240v 15 amp motors off single 240v 30 amp outlet?

    Freebird a bit different with air arc, no real point in storing air. He will hit idle fast along with the welder. Where stored air is good is smaller comp , operator managed and somewhat limited blast and sand. The pump cant make more air in the same time but it lets it run long time where it would turn off with a small tank. In my own,,, yes, could add some more tanks or bigger again but this is kist right and can do the work without turning the back/demand on. I use its tank. It provides for about as much work as a guy can do without a regroup or new sheet or flip it over.
    The basic rule is 5 hp electric can provide for a man to do what he has to do excluding serious sandblast and continuous hard disk grinding. When I was a sprout and starting my adventures with air tools I was about that and old timer said, I like electric for that and after I really get a grip how much my comp was working to turn the disk,,, which I use a lot I turn to electric but that has been a bit of a learning curve all its own,
    Last edited by Sberry; 3 Weeks Ago at 12:21 PM.

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    Re: Two 240v 15 amp motors off single 240v 30 amp outlet?

    Be different if the Op was using line,,, then I would be all for the idea of hooking a second I had up, would have been done before it was a thread. Cant see it in the pic from that angle but 6 space disconnect right behind it.
    Last edited by Sberry; 3 Weeks Ago at 12:26 PM.

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    Re: Two 240v 15 amp motors off single 240v 30 amp outlet?

    With out a doubt, My 14hp Ingersoll Rand gives me 25cfm @175psi.
    Does it cycle during air arc use? I used a rental comp on a blast job, it was a while ago but it really wasnt tuned right and I might even have tried to fix it in a different set of circumstances. Was cycling from say 100 to 130 all the time and should have been sized to 125. It was high from ground, a couple other issues and worked when it was wide open but like blasting with a yoyo.
    Last edited by Sberry; 1 Week Ago at 11:14 AM.

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    Re: Two 240v 15 amp motors off single 240v 30 amp outlet?

    Yours recharges really fast I bet, a skilled operator could use an inch air gun on it even small tank, give it a hit right before shut off. I wouldnt mind some big ga, even electronic could be seen in the shop. But I have reg on portable, I am sure you do too with 2 stage comp.
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    Last edited by Sberry; 1 Week Ago at 11:23 AM.

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    Re: Two 240v 15 amp motors off single 240v 30 amp outlet?

    I have different engine now, a liq Kaw but its essentially the same. But there is an air bottle under the skirt and another in series under the truck and fuel connected to truck tank, shares battery with welder. Will go as long as you can afford gas or until belts wear off.
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    Last edited by Sberry; 1 Week Ago at 11:40 AM.

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