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Thread: 240V, wire gauge, plug type ... the holly trinity

  1. #1
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    Default 240V, wire gauge, plug type ... the holly trinity

    I bought a new jointer, and picked up a used plainer. Both are 240v and both need to get an electrical outlet for the wall.

    Both machines have a magnetic starter on them so they are overload protected. The plainer is rated at 12amps, and the jointer at 15. Now I know from the electrical code that it is fine to put on a 20amp breaker with 14gauge wire and a nema 6-15 plug as per the section of induction motors with overload protection

    But thinking about it some more, I figure that I am going to have to run another wire into the shop anyways, so why not just run 12gauge to begin with. Am I allowed to put a nema 6-15 plug onto a true 20amp circuit? I'd rather not have to replace two perfectly good power cables to get from the nema 6-15 plug that is on both machines to a nema 6-20.

    I know that the fuse inside the electrical pannel is there purely to protect the wire that is inside the wall, and not the device that is plugged into it. But at 240v they change the style of the plug as you change the amperage.

    Help?

    Matt.
    Last edited by matt.mackinnon; 11-27-2010 at 09:19 PM.

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    Default Re: 240V, wire gauge, plug type ... the holly trinity

    Matt, for starters, you can't use 14g wire with a 20A breaker, you need 12g, 14g is only good for a 15A circuit.

    I would suggest you run something like a 60A circuit to a panel in your shop, and from there run the individual circuits you need. There is a good chance you will need more circuits in the future, like a dust collector or a band saw.

    If you do use individual circuits I would use 10g so you can easily upsize the breaker if new larger machines are ever bought, plus there will be less line loss.

    There is no problem using 20A plugs if you use a 20A circuit and a minimum of 12g wire. not necessary, but they all machines could share the same plug.
    JIM
    Calgary, AB

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    Default Re: 240V, wire gauge, plug type ... the holly trinity

    Quote Originally Posted by matt.mackinnon View Post
    I bought a new jointer, and picked up a used plainer. Both are 240v and both need to get an electrical outlet for the wall.

    Both machines have a magnetic starter on them so they are overload protected. The plainer is rated at 12amps, and the jointer at 15. Now I know from the electrical code that it is fine to put on a 20amp breaker with 14gauge wire and a nema 6-15 plug as per the section of induction motors with overload protection

    But thinking about it some more, I figure that I am going to have to run another wire into the shop anyways, so why not just run 12gauge to begin with. Am I allowed to put a nema 6-15 plug onto a true 20amp circuit? I'd rather not have to replace two perfectly good power cables to get from the nema 6-15 plug that is on both machines to a nema 6-20.

    I know that the fuse inside the electrical pannel is there purely to protect the wire that is inside the wall, and not the device that is plugged into it. But at 240v they change the style of the plug as you change the amperage.

    Help?

    Matt.
    I do NOT think it is fine to have a 14ga wire and 20amp breaker (you could draw more amps than wire is rated for before the breaker trips).

    There are people more qualified than me to answer your questions but if you are worried about the plugs at the end of the cables for the machines you can just replace those end plugs (they are cheap to buy).

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    Default Re: 240V, wire gauge, plug type ... the holly trinity

    Matt, From what I read these are run from you main panel, how many feet? You are going to get voltage drop. Run #12 wire, I often go overkill with larger motors and use #10.
    Cheers, Mark
    Today's mighty oak is just yesterday's nut, that held its ground.

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    Default Re: 240V, wire gauge, plug type ... the holly trinity

    the main house panel is 2 meters away from the garage/workshop. i am looking to do a run that is about 5 meters in length.

    power drop is not a concern. adding in new equipment is not a concern. I already have a 240v DC that I have it's own power outlet for, so the second plug will be able to run every other machine. There is only one of me, and I can't and will not run more than 1 machine at a time.

    I have looked into running a sub panel and don't see any benefit for it. This is starter home and not that i am planning on living here for the rest of my life. I would like to move and get somewhere that has enough land around it to build a proper shop that has it's own sub panel.

    my concern is purely if it's a red flag no-no to put a nema 6-15 plug onto a 20amp circuit?

    The whole reason for going 20 amp in the first place is that the jointer is 3hp and is listed at 15amp. it should not draw over that, but i don't write specs and would rather have a larger source than put up with it tripping on power up or with difficult wood. It costs the same to run a 20amp line as it does to run a 15. Why not put in the larger.

    in truth i guess it doesn't really make a hoot of a difference as long is i never get it inspected. but i'd rather stay inside code.

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    Default Re: 240V, wire gauge, plug type ... the holly trinity

    I would think that putting a 6-15 plug into a 12ga circuit would be fine so long as you use a 15A breaker (thereby effectively making your circuit a 15A circuit). I'm not an electrician, though.

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    Default Re: 240V, wire gauge, plug type ... the holly trinity

    I don't think it is legal to use a 15A plug on a 20A circuit in this application.

    I also don't think it has anything to do with 5A more of current draw being a hazard, it's just a method to ensure you don't plug a 20A load into a 15A circuit because the 20A plug won't fit.

    If you look at a 15A plug or a 20A plug you will see that the current carrying parts are the same size, just the orientation is different. Furthermore, you can plug your 15A toaster plug into your 20A T kitchen receptacle with the blessing of the electrical gods.

    billh

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    Default Re: 240V, wire gauge, plug type ... the holly trinity

    My point is, if your receptacle is a 15A receptacle and your breaker is a 15A breaker, I don't see the problem using 12ga or even 10ga wiring. I don't really see a problem with using a 6-15 plug in a 20A circuit if the receptacle is a 6-20R and the breaker is 20A. If I'm not mistaken, the 6-20R is like a 5-20R in that the 15A and 20A plugs both work.

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    Default Re: 240V, wire gauge, plug type ... the holly trinity

    Given that a 6-20R is a T receptacle that accepts either 15A or 20A 240V plugs it probably is OK but that assumes there is nothing preventing it in the codes that cover your jurisdiction.

    The US had been using 20A, 120V T receptacles for years before they became legal in Cdn kitchens.

    billh

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    Default Re: 240V, wire gauge, plug type ... the holly trinity

    Matt, if it were me, I would run it as a multiwire branch circuit using 12/3 and a 20 ampere 2 pole breaker.

    Use 20A 240V receptacles (6-20R) for the 240V machines and you can also run 5-20R receptacles for othe 120V tools.

    I used 4 inch square boxes with one 6-20R and one 5-20R receptacles in each box.

    Regards, Rod.

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    Default Re: 240V, wire gauge, plug type ... the holly trinity

    Thanks to everyone who has responded.. If I was designing a new shop that I expected to stay in for any length of time, I know that I would run a sub panel into the shop and how is best to wire for future growth.

    I do appreciate the input that has been given, though no concrete yes or no to my question. I will phone up the Electrical Safety Authority and see if they will answer it as ultimately, they decide what is accepted or not.

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    Default Re: 240V, wire gauge, plug type ... the holly trinity

    Quote Originally Posted by matt.mackinnon View Post
    I do appreciate the input that has been given, though no concrete yes or no to my question. I will phone up the Electrical Safety Authority and see if they will answer it as ultimately, they decide what is accepted or not.
    Matt, you never really asked a simple question that could be answered yes or no. There were suggestions offered to your situation, which will give you a direction to take. I see no misinformation given.
    JIM
    Calgary, AB

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    Default Re: 240V, wire gauge, plug type ... the holly trinity

    Quote Originally Posted by matt.mackinnon View Post
    Thanks to everyone who has responded.. If I was designing a new shop that I expected to stay in for any length of time, I know that I would run a sub panel into the shop and how is best to wire for future growth.

    I do appreciate the input that has been given, though no concrete yes or no to my question. I will phone up the Electrical Safety Authority and see if they will answer it as ultimately, they decide what is accepted or not.
    The inspection authority for the respective jurisdiction should alway be the first place to contact with respect to electrical advice. The directions given usually cost the same as what you get on this forum, but it will be correct. Saves a lot of churn to get the answer.
    Maybe a sticky or some other note to this effect could be placed at the beginning of this section.

    Don

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    Default Re: 240V, wire gauge, plug type ... the holly trinity

    Quote Originally Posted by Don Burch View Post
    The inspection authority for the respective jurisdiction should alway be the first place to contact with respect to electrical advice. The directions given usually cost the same as what you get on this forum, but it will be correct. Saves a lot of churn to get the answer.
    Maybe a sticky or some other note to this effect could be placed at the beginning of this section.

    Don

    Hi Don

    I put a sticky up for ESA's website over a year ago.

    http://forum.canadianwoodworking.com...ad.php?t=28926
    Mike

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    Default Re: 240V, wire gauge, plug type ... the holly trinity

    Quote Originally Posted by Mike in London View Post
    Hi Don

    I put a sticky up for ESA's website over a year ago.

    http://forum.canadianwoodworking.com...ad.php?t=28926
    Mike,
    I realize that, but the link provided takes you to the ESA FAQ's which are good but perhaps not as intuitive for all issues, and would I in Alberta rely on this site? I just phone my local inspection office for guidance.

    Don

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    Default Re: 240V, wire gauge, plug type ... the holly trinity

    Quote Originally Posted by Don Burch View Post
    Mike,
    I realize that, but the link provided takes you to the ESA FAQ's which are good but perhaps not as intuitive for all issues, and would I in Alberta rely on this site? I just phone my local inspection office for guidance.

    Don
    No question the best option is to talk to an inspector, but you can ask questions on ESA's FAQ as well, it just takes time to get your answer. General answers would be good for Alberta as well.
    Mike

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    Default Re: 240V, wire gauge, plug type ... the holly trinity

    Quote Originally Posted by matt.mackinnon View Post
    Thanks to everyone who has responded.. If I was designing a new shop that I expected to stay in for any length of time, I know that I would run a sub panel into the shop and how is best to wire for future growth.

    I do appreciate the input that has been given, though no concrete yes or no to my question. I will phone up the Electrical Safety Authority and see if they will answer it as ultimately, they decide what is accepted or not.

    Matt, a single 15 ampere receptacle cannot be protected by a 20 ampere breaker.........Rod.

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    Default Re: 240V, wire gauge, plug type ... the holly trinity

    Quote Originally Posted by Rod Sheridan View Post
    Matt, a single 15 ampere receptacle cannot be protected by a 20 ampere breaker.........Rod.
    So, I am to understand that you cannot put a 15amp receptacle onto a 20 apm breaker circuit. The size of the receptacle must match the breaker size?

    Thanks Rod.

    Matt.

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    Default Re: 240V, wire gauge, plug type ... the holly trinity

    Quote Originally Posted by matt.mackinnon View Post
    So, I am to understand that you cannot put a 15amp receptacle onto a 20 apm breaker circuit. The size of the receptacle must match the breaker size?

    Thanks Rod.

    Matt.
    Basically, any part of the circuit must meet, or exceed, the capacity of the breaker.

    One way to look at it is the breaker is the protection for the circuit, and must be rated as the weakest link.
    JIM
    Calgary, AB

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    Default Re: 240V, wire gauge, plug type ... the holly trinity

    Now consider the 15A toaster, kettle, can-opener, coffee-maker plug being used with a 20A GFCI kitchen receptacle.

    The 240V T-slot receptacle is the same situation. The receptacle is rated for 20A but the plug isn't.

    billh

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