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Thread: Wire gauge too big?

  1. #1
    Join Date
    Jan 2009
    Location
    Niagara, Ontario
    Posts
    657

    Wire gauge too big?

    Good evening.

    I got hold of some 2/3 copper wire, real cheap - $0.00 (taxes included). I am planning to set up a sub panel in my attached garage. The distance from the main panel to the sub panel will be about 14 feet and I want to run the sub off a 60 amp breaker on the main panel.

    Is there such a thing like too "thick" in wiring? Any drawbacks of using a wire that is rated for higher amperage than what I will be using? The wire I have is the shielded (?) type, like Romes or BX. Sorry, not too strong in electrical terminology.

    Thanks.
    Darius

  2. #2
    Join Date
    May 2009
    Location
    N.W. Missouri
    Posts
    1,145
    Heavier wire is fine.

    John

  3. #3
    Join Date
    Jun 2007
    Location
    Wichita, Kansas
    Posts
    1,795
    Financial considerations aside, there are no electrical theory drawbacks with using heavier gauge wire than required by code - after all, code requirements are typically minimum acceptable configurations. There may be mechanical drawbacks. The heavier gauge wire will be stiffer, making it more difficult to work with and, if considerably heavier than needed, may be larger than the terminals on the devices can take. I believe most devices specify a gauge range for the terminals.

    I'd say any gauge between those two limits, code minimum gauge and device maximum gauge, and you're good to go.
    Tom Veatch
    Wichita, KS
    USA

  4. #4
    No, a heavier-than-needed wire is like an uncrowded highway. As Tom noted, however, heavier wires are much harder to work with. Having just spent some time wresting with some 10/2 wire for my new cyclone, I can attest to that.

  5. #5
    This wire is really big - if you're only putting 60A in the subpanel, you could get by with 6ga. However, the 2ga would be good for 100A, if you ever decide you need more in the future.

    If you had a whole spool of it you wanted to use for a project, I might recommend you sell it and buy the correct size, as you'd probably make money, but for only 14' - go for it.

  6. #6
    Join Date
    Jan 2009
    Location
    Niagara, Ontario
    Posts
    657
    There is only 30 feet of it. A leftover from a job at work and nobody wants it. Yes, the wire will be pretty hard to work with but I can't complain considering the price.

    Thank you all for your replies.

  7. #7
    You need to check if the lugs of the circuit breaker will accept the conductor you want to use, cutting off "excess" strands is not a good thing to do.

    250.122 (2005 NEC) requires that if the ungrounded (hot) conductors are increased in size the equipment grounding conductor(ECG) (if used) must also be increased in size proportionately according to the circular mil area of the ungrounded conductors, this can make a cable w/ it's mininum sized ECG a no can do situation where oversizing conductors are being done.

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