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-   -   Secondary 100 Amp Feeder Wire Size (https://www.askmehelpdesk.com/showthread.php?t=65368)

  • Feb 22, 2007, 02:55 PM
    tdcalahan
    Secondary 100 Amp Feeder Wire Size
    Hello to all. I am running a feeder wire in 2" conduit from my 100 amp breaker in my house panel to my 100 amp garage panel approximately 160' away. I am wondering if #1-#1-#2 Aluminum is sufficient with a #6 Copper ground. Thanks for the help.
  • Feb 22, 2007, 03:30 PM
    tkrussell
    The voltage drop will be 6.5 volts across each 120 leg to neutral assuming the load is 80 amps.

    Recommended maximum allowance is 3% or 3.6 volts. If the load does not exceed 40 amps, the voltage drop will be 3.2 volts, which will be acceptable.

    If there will be large motors, say 5- 10 HP, they may have a problem starting due to the locked rotor amperage combined with any other running load.
  • Feb 22, 2007, 04:50 PM
    jeff bouchey
    Quote:

    Originally Posted by tdcalahan
    Hello to all. I am running a feeder wire in 2" conduit from my 100 amp breaker in my house panel to my 100 amp garage panel approximately 160' away. I am wondering if #1-#1-#2 Aluminum is sufficiant with a #6 Copper ground. Thanks for the help.

    Yes # 2 Al or #3 Cu is sufficient. #6 Cu ground is also sufficient. Just remember to remove the bonding screw in the panel in the garage. I suggest burying a ground plate approx. 2' in the ground and tying it to the panel itself
  • Feb 22, 2007, 05:12 PM
    tkrussell
    Do not connect the new panel to a grounding electrode as suggested.

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