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Thread: Wiring for my new DC.

  1. #1
    Join Date
    Nov 2006
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    Rochester Hills, MI
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    940

    Question Wiring for my new DC.

    Hi folks,
    I recently purchased the Harbor Freight 2hp 5 micron DC unit. It works OK, but I've had trouble getting it to start up at times. I'm pretty sure that it's because I only have 15A outlets in the basement at this time. I think I'm going to have to change that. But for now, I'm going to put in a dedicated 20A circuit just for the DC. Most of the time it will be on my table saw. So I think I'm going to install the outlet over near the TS so I can plug the DC directly into the outlet. But there will be times that I want to use the DC in other locations. I was planning on just putting one outlet on the circuit, but that limits where I can use the DC. Like I said, most of the time it will be in one place over by my TS.

    I thought about picking up a short 25' heavy duty 12 ga. extension cord for times that I might want to move the unit. Then I wondered if it would be worth getting (or maybe making) a short 25' 10 ga. cord. The circuit would be 12 gauge so does it make any sense, or would there be any benefit to using a heavier gauge extension cord? I guess I could just install maybe another outlet or two in the circuit, thus avoiding the need for an extension cord at all. I'd really prefer to eliminate any extension cords if possible. Even when I plug this beast 2hp motor into the 15A circuit, it struggles to start, and sometimes won't.

    I think I've got some electrical upgrades to make in the shop SOON.
    "The bitterness of poor quality remains long after the sweetness of low price is forgotten"

  2. #2
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    May 2007
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    There are some charts out there to show the max amperage's for distances of the various wire gauges. I'll see if I can locate one, but at the lengths you're talking about, 12 gauge would be fine. I'm not sure I've been running mine off of a 20 amp circuit. It's one of the older plugs in the shop and not sure of the wire/breaker size, most the older breakers were 15 amp. I know the cord is only a 14 gauge cord. Will have to re-evaluate mine when I get home, but it's been running fine on it.
    Darren

    To a small child, the perfect granddad is unafraid of big dogs and fierce storms but absolutely terrified of the word “boo.” – Robert Brault

  3. #3
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    Poway, CA, near San Diego
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    The cord on the unit itself might be undersized also.

    Bob

  4. #4
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    How far is it to your panel John? I think this calculator is being conservative, but for 20 amps it says 12 gauge will go about 45'. Seems like I've seen charts showing up to 70' or so, but it may be taking voltage drop into account.

    http://www.gorhamschaffler.com/wire_...alculator.html
    Darren

    To a small child, the perfect granddad is unafraid of big dogs and fierce storms but absolutely terrified of the word “boo.” – Robert Brault

  5. #5
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    Quote Originally Posted by Bob Meyer View Post
    The cord on the unit itself might be undersized also.
    That is possible if running though another long cord, can do 20 amps on a 14 gauge cord for about 25' total
    Darren

    To a small child, the perfect granddad is unafraid of big dogs and fierce storms but absolutely terrified of the word “boo.” – Robert Brault

  6. #6
    Join Date
    Nov 2006
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    Ahhh, I just discovered a problem...

    I have three outlets that are mounted on the posts running down the center of the basement. One duplex outlet on each of the poles. I'd like to have two outlets at each of those locations. I traced the wire in that circuit and those three outlets are the only things on that circuit. It's all #14 wire, but the breaker controlling that circuit is 20A! Someone dropped the ball there and I never noticed it. I'm headed to the BORG in a little bit. I've got a coil of #12 wire already, but I'm going to pick up some new outlets and two gang boxes and rewire the entire circuit. I think I'll even get a new 20A breaker.

    I just looked at the label on the DC and it says the motor is 120V/60hz./14A. It's a 20A breaker but the wiring is only #14. I'm gonna put in a whole new 20A circuit for those shop plugs and try the DC on that circuit. If it works fine, I'll just put in the dedicated 20A for the DC and be done with it. A #10 extension cord wouldn't hurt anything, it would just be less voltage drop.
    "The bitterness of poor quality remains long after the sweetness of low price is forgotten"

  7. #7
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    Looks like we were all typing at the same time.

    Last time I had the problem, the unit was plugged into the outlet closest to the panel. It's only about 7' tops. Maybe 15' of wire from the breaker to the outlet. I just talked to my dad and he said that it sounds like maybe the start capacitor has a problem. Well since I want my power outlets in the shop upgraded anyway, I'm going to start there. Once I have a good quality 20A circuit installed, I'll try it out. If it doesn't start up correctly, there's a problem with the unit and I'll take it back to HF and have them replace it. I only bought it about 3-4 weeks ago.

    Thanks for the input guys!
    "The bitterness of poor quality remains long after the sweetness of low price is forgotten"

  8. #8
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    A (true) 2hp motor is stretching the capabilities of a 120V~ circuit on startup.

    Since you're already rewiring a circuit, consider running a new, dedicated 20 amp 220/240V~ circuit, and rewiring your DC for 220/240. It'll draw less current (per leg) and probably start much easier.
    Jim D.
    Adapt, Improvise, Overcome!

  9. #9
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    I thought about that Jim.
    A lot of bigger motors I've seen are capable of being rewired to run on 220. I can't find a label of any kind on this DC motor. I'll have to look in the manual. If it's possible to run on 220, I'll definitely do it.

    I just got back from the BORG with the stuff to rewire the existing circuit. We'll see if that helps. I'll report shortly, it shouldn't take me too long to redo this circuit.
    "The bitterness of poor quality remains long after the sweetness of low price is forgotten"

  10. #10
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    Quote Originally Posted by Jim DeLaney View Post
    A (true) 2hp motor is stretching the capabilities of a 120V~ circuit on startup.

    Since you're already rewiring a circuit, consider running a new, dedicated 20 amp 220/240V~ circuit, and rewiring your DC for 220/240. It'll draw less current (per leg) and probably start much easier.
    The HF DC is 120v only.
    Darren

    To a small child, the perfect granddad is unafraid of big dogs and fierce storms but absolutely terrified of the word “boo.” – Robert Brault

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