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Thread: 220v from 2 x 110v plugs

  1. #1

    220v from 2 x 110v plugs

    Ok, so I'm going to preface this question with a statement... I am a carpenter, not an electrician, so please dont laugh if I'm completely off base.

    I am about to rent a shop space, and buy my first Bandsaw, Jointer and Planer. Currently I am limited to 110v outlets, and the breaker panel is in the space next to mine, so I dont have access to it, and I would not be allowed to run the new cables either. I would like to buy some higher quality equipment, that requires 220v. Is there someway that I could build a 220v extension cable that plugs directly into two seperate 110v outlets?

    Thanks for any help that you can offer.

    (It's taken me a year to find this place, so waiting for a place with 220v isnt an option.)

  2. #2
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    A non-three phase service uses two hot wires (legs). Both wires are 110 volts. In order to achieve 220 volts, you need to tap into both legs.

    While I can't say that both legs are not present in your space, I'm willing to bet that it is a code violation to combine both legs outside of the breaker box. The first think that comes to my mind is that the breakers would act independently leaving you with the possibility of having half of your power trying to run the equipment.

  3. #3
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    Dec 2007
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    Don't worry, you are not the first person to ask this

    It just won't work. Trying to get 220 from two 110 outlets is like connecting two 90psi hoses and expecting 180 psi.

  4. Depending on the age of the building concerned, he might end up with 208V, if it's a 3-phase panel.

    If it was a single phase supply, AND you had 2 legs to tap into, it is *theoretically* possible.

    Further to Richard's concerns, you'd have real safety issues involved. If one circuit breaker tripped, and you were to unplug the cord to troubleshoot, the male pins of that cord would be live with the other leg's 110 volts. Major hazard. I'm pretty sure an inspector would tell you to take it out once he got done shouting at you.

    You'd be effectively making something analogous to a 110V open neutral situation, whereupon the neutral end coming from the equipment is at line voltage.

  5. #5
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    Quote Originally Posted by Todd Pretty View Post
    Is there someway that I could build a 220v extension cable that plugs directly into two seperate 110v outlets?
    Absolutely not!!!
    Never, under any circumstances, combine a sleeping pill, and laxative on the same night.

  6. #6
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    Could you...Yes...if you can find two outlets that were on different legs within the panel (not going to be an easy task). Should you...NO WAY...it violates so many codes and creates huge electrical hazards that we couldn't list them all. The first of which is the lack of the single trip breaker, a 220V breaker trips and disconnects both hot legs if either overloads. In this situation, one breaker could trip but not the other, then you would only have 110 to the motor and it would fry. Adios, 220V xHP motor.

    You'll need to either stick with 110V, find way to get some 220 lines run, or wait for another place. I'm sorry for the bad news.

  7. #7
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    Todd,

    The answer to your question is that Yes, you could build such an extension cord.

    There are problems that you could run into and, as Duncan noted, you would need to know if the service in the building is 3-phase or not. As noted, you could trip 1 of the 2 breakers and that wouldn't be good.

    Electrically, it could work. The service would need to be standard 120/240v single-phase. You would need to be able to locate outlets on 2 circuits that were both on different breakers and on different busses in the panelboard.

    = = = = = = = = = = =

    My recommendation is that you hire an electrician and have a 240v, 20 amp circuit installed in the space that you're renting. It's safer in the long run. If you're paying for the electrician, I would think that the building owners shouldn't have an objection to a licensed sparky doing the work.

  8. #8
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    Quote Originally Posted by Anthony Whitesell View Post
    Should you...NO WAY...it violates so many codes and creates huge electrical hazards that we couldn't list them all. The first of which is the lack of the single trip breaker, a 220V breaker trips and disconnects both hot legs if either overloads. In this situation, one breaker could trip but not the other, then you would only have 110 to the motor and it would fry. Adios, 220V xHP motor.
    Sorry, but I believe that what you posted is incorrect.

    First, the electrical codes are designed to protect the building. There is nothing in the codes that applies to what you plug into the circuits even if we look at it and say "bad idea".

    Second, as soon as one of the 2 breakers tripped - the motor would stop. An analogy is using a single pole vs. double pole switch for a 240v motor. Either way the motor will stop.

  9. #9
    What you are proposing is a good way for people to get hurt/killed, if one attachment plug is removed, 120 volts can back feed through the equipment on the load side energizing the prongs of the plug that was removed,my advice is hire someone qualified to do the work.


    This is the stuff that becomes fodder for the Darwin Awards website.

  10. #10
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    I am with Anthony, NO WAY. There is a reason that 220 brakers must be connected so if one trips the other trips... There is always ways to jerry-rig something to make it do what you want it to do. However, there are some things that you should not try to jerry-rig. I agree you need 220 for most tools. I would try to find another space witrh 220.

    Sam

  11. #11
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    Todd,
    The two separate 110 plugs are probably on the same circuit and if so it will be as Allan F. described with the two 90 pound air lines combined will still be 90 pounds of air not 180 PSI.
    My suggestion is for you to buy 110 volt equipment or make arrangements to get a 220 volt tap off of the power panel. There is also the possibility that the plugs that are available to you are 15 amp plugs protected by a 15 amp breaker and this is not enough to run any heavy duty equipment.
    The only other option is to get back in line for another shop because if you don't have access to the needed power you should forget the idea. You could always buy a heavy duty generator that will handle your power requirements.
    David B

  12. #12
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    First off - NO

    Now technically speaking, a normal single phase (residential) system has two hot legs, a neutral, and a ground. Voltage between the two hot legs is 230v, and between either hot leg and neutral 115v. You could theoretically have a situation where two outlets remote from one another might be on seperate hot legs and do some fancy wiring of cords and get real lucky and.............

    On second though, NO
    "Never eat more than you can lift" - Anon.

  13. #13
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    Quote Originally Posted by David G Baker View Post
    Todd,
    The two separate 110 plugs are probably on the same circuit and if so it will be as Allan F. described with the two 90 pound air lines combined will still be 90 pounds of air not 180 PSI.
    My suggestion is for you to buy 110 volt equipment or make arrangements to get a 220 volt tap off of the power panel. There is also the possibility that the plugs that are available to you are 15 amp plugs protected by a 15 amp breaker and this is not enough to run any heavy duty equipment.
    The only other option is to get back in line for another shop because if you don't have access to the needed power you should forget the idea. You could always buy a heavy duty generator that will handle your power requirements.
    Actually if you use two wires from the same pole you get zero volts differential, not 120 volts, since they are in phase.

    A 15 ampere breaker is large enough to run shop equipment, I have a General 650 that only draws 12.5 amperes (3HP) so it runs from a 15 ampere circuit.

    Same for my General Shaper, Bandsaw, Hammer A3-31 planer etc.

    Regards, Rod.

  14. #14
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    Todd,

    I think you have the idea that to do this, even if it "works", is a bad idea in general. So I see some options:

    (1) Try your new equipment with what you've got and see if it'll work.
    (2) Talk to the landlord about getting you some 240 V in your space...offering to hire a licensed electrician might get you what you want.
    (3) Inspect the breaker box and/or outlets in your shop...could they be possibly upgraded from 15 A to maybe 20 A? If they are run with #14, you are SOL (possibly...can new wires be EASILY pulled?)...if they were run with #12, then you just gained another 5 A on your 120 V circuits and it may help in situation (1) over situation (2).
    (4) Maybe a 240V plug could be placed right at the breaker box and you could run an extension cord to your shop? This one may have issues as well since it is more or less a "permanent" extension cord but it could be the least expensive.

    I'm curious. If you don't have direct access to the breaker box, what happens if you trip a breaker in your shop? Will it take an hour or two to get someone to reset the breaker? Sounds like a pain to me. You may wish to negotiate some reasonable access to the breaker box in your lease agreement....
    Crown Molding: cut, cope, cuss, caulk, chill....

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  15. #15
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    Quote Originally Posted by Todd Pretty View Post
    .........and the breaker panel is in the space next to mine, so I dont have access to it.........(It's taken me a year to find this place, so waiting for a place with 220v isnt an option.)
    Todd, KEEP Looking for workspace! What if you trip a circuit?? No access to even reset the breaker Next Door? Hmmmm... Keep Looking!
    Necessisity is the Mother of Invention, But If it Ain't Broke don't Fix It !!

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