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Diameter vs current rate of a copper wire

  1. Jan 6, 2009 #1
    Hi all,

    I am planning some electrical installation in my home and I am not sure about the norminal current that the wire can tolerate. can any give me the ref table or some link of that, I mean for certain diameter (mm), the wire can bear a current (amp).

  2. jcsd
  3. Jan 6, 2009 #2


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    Science Advisor

    This table agrees with what I've read elsewhere, and I believe it's for continuous current with air-cooling (though it uses AWG--American Wire Gauge--which is good, since it's how the wiring is sold at the Hardware store!):

    If you go down to your local hardware store, you can probably pick up a book that covers this and offers tips on planning your project, and how to install / renovate / replace various things (e.g. Black and Decker Guide to Home Wiring).

    If you're doing a fair bit of stuff, I would also strongly recommend you find out what electrical regulations apply in your jurisdiction (i.e. what you can do, and what has to be left to an electrician), and pick up a copy of the abridged code book, which often comes in pretty handy for standard wiring tasks. Far too many people just go cowboy on this stuff, and end up paying for it later.
  4. Jan 6, 2009 #3


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    Staff: Mentor

    MATLAB beat me to most of this, but I still need to point out -- modifying these things in a dwelling generally requires permits and inspections by your city code enforcement department:

    Plumbing, Electrical, Structural.

    They are usually pretty helpful linking you up with the applicable local codes (and the NEC in this case). You should not be thinking of taking advice from a web forum and doing this work yourself without getting the applicable permits, and having your work inspected and signed off by the city.

    Beyond the common-sense aspects involved, when you go to sell the dwelling, you will be asked if you did any of the above kinds of work to the home, and if you had the applicable permits. If you lie, and you are found out (pretty easy), that can do all kinds of bad things to the sales process. Also, if there is a fire in the dwelling after you do work without permits and inspections, guess who is liable for the damage and any injuries?

    Even using licensed contractors, I've caught a couple trying to do work without getting the permits, and I've caught them doing things that would have been dangerous because they weren't obeying the local codes and the NEC. Like overloading circuits, and running too-small gauge wire too far....
  5. Jan 7, 2009 #4
    Thank you both for the help. I will look for the regulations as well.
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