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Thread: What is Hard Drawn Copper?

  1. #1
    Join Date
    Feb 2003
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    Bremerton, Washington
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    What is Hard Drawn Copper?

    Section 230.23 (overhead service drop conductors)31 (B) is the minimum size of service conductors, which is 8 AWG,
    Exception: Conductors supplying only limited loads of a single branch circuit — such as small polyphase power, controlled water heaters, and similar loads — shall not be smaller than 12 AWG hard-drawn copper or equivalent.

    What is hard drawn copper? Can I go to my local electrical house and order a spool of it?
    I assume its used for strength???
    Moderator-Washington State
    Ancora Imparo

  2. #2
    Join Date
    Feb 2003
    Location
    South San Francisco CA
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    150

    Re: What is Hard Drawn Copper?

    Tom, hard drawn copper wire is wire that is not annealed after the drawing process. Annealing makes the copper more flexible. Hard drawn has at least 150% more tensile strength than annealed. I don't know if a regular electrical supply would stock it or if you would need to special order it.
    steve

  3. #3
    Join Date
    Feb 2003
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    Indianapolis
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    Re: What is Hard Drawn Copper?

    I am sure that you that you do not to ever use HD Cu. It is very hard to handle, especially in the larger sizes. Electric utilities have used it for years because of the strength and have now moved to Al. due to the cost savings. I attempted to use some scrap HD Cu. for running from an antenna mast to a ground rod a long time ago. This turned out to be a bad idea since I was trying to use #4 solid HD Cu. and it was as stiff as a ____. I have never used smaller HD wire but the same principals would apply (I think).

    Since I have never had any other experience with HD Cu., I may be very wrong. That would be the first time since . . .
    Charlie Eldridge, Indianapolis, Utility Power Guy
    Responses based on the 2011 NEC, unless stated otherwise.

  4. #4
    Join Date
    Feb 2003
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    United States
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    Re: What is Hard Drawn Copper?

    Tom, Hard Drawn Copper is typically used for overhead distribution circuits on insulators and thus run straight. As pointed out, HD Copper is difficult to bend even in larger sizes where it is stranded. I don't know of any wholehouse house in my area that carries it since it would typically be a utility product. Years ago I used it for overhead work and for the runs down poles to ground rods when working for a utility company, but have never used it as an electrical contractor. I think now we see more steel reinforced aluminum (ACSR) for overhead lines. I would suspect the main reason for the HD copper used for overhead lines was, better resistance to wind and less sag on spans between poles.

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