Wiring a garage

Discussion in 'Electrical Forum discussion & Blog' started by sirjonas, Oct 12, 2011.

  1. sirjonas

    sirjonas New Member

    Messages:
    4
    Location:
    Ontario
    I was wondering if a 10/3 wire would be heavy enough to run power out to my garage? I do need a 220 plug out there for my welder. I know my breaker service in the house would support it. And i have a Breaker box that i can hook up in the garage as well. The wire would be about 80 to 100' long. Can I get away with a 40 amp breaker coming from the house? Thanks any help or direction would be greatly appreciated.
    jonas
  2. Chad Schloss

    Chad Schloss Member

    Messages:
    330
    Location:
    USA
    how many amps does your welder require? 10ga supports up to 30a. you would have to have a 30a breaker in the main panel and wire the panel in the garage as a subpanel. (Make sure to keep the neutral and ground separate) is the garage detached? if so, i think you need to install ground rods. an electrician will chime in shortly i'm sure. I am currently wiring my attached garage so I know what you are going through. I ran 6/3 to the garage since I had extra from a previous project.
    Last edited: Oct 12, 2011
  3. ActionDave

    ActionDave Electrician

    Messages:
    363
    Location:
    Colorado
    Assuming the garage is detached and you are not going overhead you are going to need a trench, and you are going to put wire in the trench.

    Are you going to put the wire in conduit, so that if you ever have a problem it is easy to remedy without a shovel and lots of backbreaking labor out in the hot sun or freezing cold?
  4. sirjonas

    sirjonas New Member

    Messages:
    4
    Location:
    Ontario
    yes the garage is detached and i was going to underground with it. I was not sure about the conduit thu. And i dont believe my welder draws anymore than 30 amps. And how do you wire up a subpanel? i have another breaker panel that i picked up at a garage sale would this work?
    Last edited: Oct 13, 2011
  5. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,566
    Location:
    North Carolina
    If installing a 240 volt circuit to a detached garage one MUST install four conductors, two hot, one neutral, one equipment grounding conductor.
    A grounding electrode system MUST be established at the remote panel. The panel at the detached garage must be rated as service equipment and shall be at a readily accessible location nearest the point of entrance of the conductors or installed outside the garage.
  6. Chad Schloss

    Chad Schloss Member

    Messages:
    330
    Location:
    USA
    Subpanel Wiring in a detached garage. Note the separation of the neutral and ground and the panel is not bonded to the neutral. Also note the separate ground rod required.

    [​IMG]
  7. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    Let's get back to the wire. He mentioned he wanted to run 10/3 , 100 feet, off a 40 amp breaker. Any comments on THAT.
  8. Spaceman Spiff

    Spaceman Spiff Architect

    Messages:
    277
    Location:
    Salt Lake City, Utah
    He needs to use #8AWG wire to have an acceptable voltage drop at 40A and 100'. Need to use #8AWG anyway for 40A. For 30A #10 is fine. Both calculate to about 2.5% voltage drop at full load.
  9. sirjonas

    sirjonas New Member

    Messages:
    4
    Location:
    Ontario
    The reason i was asking about the 10/3 wire was i might be able to get it pretty cheap, but i just gotta check my welder first and see what it draws.
  10. leejosepho

    leejosepho DIY scratch-pad engineer

    That wire will do well enough at supplying power for your welder at that distance, but you can only feed it with a 30A breaker at the house ... and please do as suggested here and run four wires out to the detached garage and then be sure the sub-panel there is installed and wired correctly! My own recent mess began when someone else only ran three wires out and then only used two of them for powering everything connected at the far end.
    Last edited: Oct 14, 2011
  11. sirjonas

    sirjonas New Member

    Messages:
    4
    Location:
    Ontario
    Well i just found out my welder requires 50amps for input, so i will either have to find some 6/3 wire or find somebody to trade me for a 110 mig welder or 220 welder that does not draw as much.
  12. leejosepho

    leejosepho DIY scratch-pad engineer

    Be cautious about any 110V MIG you might get. Lincoln and Hobart make some decent ones that will work well either with flux-core or with gas, but they cost quite a bit more than most of the cheapies you can find elsewhere and just do not burn all that well and do not last. Also, you might try connecting your welder somewhere and checking its actual amperage draw while doing the actual kind of work you intend to be doing. 50A is likely only needed for running that welder "wide open" with large wire doing heavy work, and you might just find 30A is plenty for what you actually do. The little 120V arc welder I have calls for 30A, but it only actually needs that for burning a full stick of 1/8" rod all at once. If I only burn part of a stick or use 3/32" rod, the welder does just fine with only a 20A circuit supplying the power.
    Last edited: Oct 15, 2011
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