Wiring 220V Compressor

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  • chris-p


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    #3683

    I upgraded my compressor for my basement to run my blasting cabinet. The old compressor was 120, I got a bigger 60 gallon, 220V 5hp Machine to take over!

    I have a finished basement, so, is it stupid to jump the 220 off the dryer plug? You could obviously only run 1 at a time, but just curious. Otherwise, if I run a fresh lead, I will be into drywall repair. Not a huge deal, but if I could get the 220 from the dryer outlet, would save a bit of work.

    This is a true 5hp as well. It has an electronic starter to get her going.

    Its wired so that the 220 IN goes to the electronic starter, then from there to a 220 V plug, which the motor plugs into.


    chris-p


    Replies: 2456
    Topics: 153
    #32275

    ….or, I make a lead with a 220V plug on it, that is wired into the electronic starter, so when I want to use the compressor, I unplug the dryer, and plug in the compressor. That might be better.


    frankr

    US Member - 1 Year (includes $3 online payment fee)
    Replies: 6715
    Topics: 51
    #32276

    That certainly would be the easiest and best way. Can we assume the compressor draws less amps than the dryer? If more, it may trip the breakers. All depends on the numbers.


    adam1961

    Canada Member - 2 Years
    Replies: 366
    Topics: 88
    #32277

    Chris,
    Your dryer plug should be protected at 40A and the compressor likely only needs 30A, so you are good on that front. Now when you have gone out, and the Mrs. is tryIng to do the laundry and you left the compressor plugged in……maybe that drywall repaire doesn’t seem so bad 🙂


    jeff-register

    US Member - 2 Years
    Replies: 1564
    Topics: 54
    #32281

    Chris,
    I have had my electrical contractors license here in Arizona. Just because it’s 240 volts (check with a meter) you still need to find your rla amperes. That is your running load amperes. Multiply that times 125% to come up with your required amperes. Now your dryer outlet @ 30 amperes you should use 80% of that max which is 24 amperes. Now compair your 24 usable amperes to your motor RLA is to see if it is a match. Remember to use 125% times your RLA, If your numbers are good buy a S.O. type cable with a 4 wire rating. It should have two for 240 volts, one for a grounded conductor usually for the control circuit voltage 120 VAC & the grounding circuit for bonding the compressor to the building ground system. Most compressors only use three wires but if it is newer it will have 120 for the control voltage. Let me ask this. Is your dryer plug have a 3 or 4 pin rectepical. Match the cord cap to the one installed. To make that easy look on the recteptical for the N.E.M.A. number & tell the sales guy is that is what you have to get the correct match. N.E.M.A. = National Electrical Manufacturing Association. If this confuses you send me an E mail @ jeff.50@cox.net… & I’ll help you do it correctly. One more thing, The dryer recept should be rated at 30 amperes. If that is not enough #10 wire, You should install a 50 ampere two pole common trip circuit breaker, Number #8 stranded wire THHN type insulation & then at the compressor site fuse it down to the required amperes. Don’t forget to get your amperes from the motor name plate & find the R.L,A. running load amperes times 125% to come up with your requirements.
    Be careful & DO NOT build a fire hazzard!!
    Jeff


    chris-p


    Replies: 2456
    Topics: 153
    #32283

    Yeah, I hear ya Adam. The only rule of the basement, is I need to leave her a path to the washer/dryer! She almost lost a finger trying to move some Big Twins I had laying in the way one day.

    You are right, the compressor requires a 30amp.

    Thanks guys. Im going to hunt my local junk yard for a dryer plug for now, and will wire up a fresh lead when I get some time. I have about 5 motors sitting that need finished. Its amazing how often you use your compressor. You don’t realize until you don’t have it anymore.


    chris-p


    Replies: 2456
    Topics: 153
    #32284

    Thank you Jeff Register. I totally agree, don’t want to do anything unsafe, which is why I asked here. I can take a motor apart blindfolded, but know diddly squat about electricals.


    jeff-register

    US Member - 2 Years
    Replies: 1564
    Topics: 54
    #32286

    Adam,
    Everyhouse I ever wired had a 30 ampere circuit breaker. By the way that 30 ampere rating protects only the wire, not equipment. When we did industrial or commercial services we fused down with a disconnect with in eye site, that’s national electric code. The cord cap makes it a disconnect but now it needs to be fused down to match the machine. Don’t forget the motor per NEC should be rated at 125% for start ups again per NEC code. I’m just trying to help you do it correctly is all. Drawing off of a 30 amp service rated at 80% (24) amps will not correctly power your compressor under pressure & trying to start, It will not & just hum & overheat.
    Jeff


    chris-p


    Replies: 2456
    Topics: 153
    #32287

    Jeff,

    Im going to start a new thread in Dockside, so I can post pics there.


    jeff-register

    US Member - 2 Years
    Replies: 1564
    Topics: 54
    #32291

    Chris, I have wired everything from houses to hospitals to hi rises to sewer pumping stations running by it’s self AKA automated control. I’m just hoping you do it safely for your family, the home & the compressor. When painting an outboard you don’t want it to stop pumping half way through!
    PLEASE do it safely!! Look at the news & see how many house fires there are because someone ignored the code. Everytime there is a fault & fire the national electric code book gets a revision. Let someone else make the mistakes. You will sleep better at night when your family is safe!!

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