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Thread: Aluminum Feeders

  1. #1
    Join Date
    Feb 2008
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    Aluminum Feeders

    Ok so I Have been discussing the topic of feeder wire size with some of my Co-workers And we can not all agree on the answer.What is the correct size
    Aluminum feeder for a 208v 200A 3-p 4-wire Panel no more than 160'
    in length in a commercial Building.

  2. #2
    Join Date
    Feb 2003
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    Florida
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    7,289
    Assuming your load does not exceed 180 Amperes, you would be permitted to use 4/0 AWG AL conductors (not considering voltage drop).

    Table 310.16 and 240.4(B)
    Bryan P. Holland, MCP

  3. #3
    Join Date
    Feb 2008
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    So if my load is calculated at 145A, and my distance is 160 Ft, is 4/0 OK ?
    At what length does voltage drop come in Play?
    Also the terminations in a panel are rated for 75 Degrees,
    do I have to run a wire rated for 75 degrees ? or is wire rated for 90 degrees OK??????????

  4. #4
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    May 2007
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    Baton Rouge
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    Yes, 90degree wire is just fine
    Jason

  5. #5
    Join Date
    Feb 2008
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    12
    Quote Originally Posted by B-Mike
    So if my load is calculated at 145A, and my distance is 160 Ft, is 4/0 OK ?
    At what length does voltage drop come in Play?
    Also the terminations in a panel are rated for 75 Degrees,
    do I have to run a wire rated for 75 degrees ? or is wire rated for 90 degrees OK??????????
    So the feeders are protected at 200A?
    I would think that 110.14(C)(1)(b) would come into play.
    Are there any terminals that are rated for 90 degrees?
    Is'nt the 90 degree column just for derating?
    My answer is 250KCMIL.

  6. #6
    Join Date
    Jul 2003
    Location
    New Jersey
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    Quote Originally Posted by Gogreen100
    My answer is 250KCMIL.

    That would work also, although Bryan gave the correct answer for the minimum size feeder which is #4/0 Al, (75 degrees C, @ 180 amps). 240.4(B) allows you to go up to the next standard OCPD which is 200 amps.


    Voltage drop for 145 amps and 160' would be about 1.8% which is fine. You can check that here:

    http://www.electrician2.com/calculat...culatoradv.htm
    Rob

    Chief Moderator

    All responses based on the 2011 NEC unless otherwise noted

  7. #7
    Join Date
    May 2007
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    Fort Lauderdale/ Miami
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    Quote Originally Posted by infinity
    That would work also, although Bryan gave the correct answer for the minimum size feeder which is #4/0 Al, (75 degrees C, @ 180 amps). 240.4(B) allows you to go up to the next standard OCPD which is 200 amps.


    Voltage drop for 145 amps and 160' would be about 1.8% which is fine. You can check that here:

    http://www.electrician2.com/calculat...culatoradv.htm
    Its fun to calculate, but you will usually find that you dont need to compensate for voltage drop until you get into the 300' range.

  8. #8
    Join Date
    Feb 2008
    Posts
    6

    Cool Aluminum Feeders

    The only thing is that the breaker that is feeding the wire is 200A.
    is 4/0 aluminum OK ?????? ,
    ore do i have to use 250 Mcm aluminum ???????

  9. #9
    Join Date
    Jun 2004
    Location
    North Central Texas
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    4/0 is okay as has been stated above. There isn't a 180 amp breaker so you can go up to the next size breaker as long as your load does not exceed 180 amps.
    Tony Hill

  10. #10
    Join Date
    Feb 2008
    Posts
    6

    Talking

    Thank you All.

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