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Thread: AL tri plex and bare EGC-N for 3 ph sub feeder

  1. #1
    Join Date
    Oct 2005
    Location
    Interior Alaska
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    42

    AL tri plex and bare EGC-N for 3 ph sub feeder

    Attached are pic of sub panel I have been asked to use for 3 phase compressors and drier.

  2. #2
    Join Date
    Oct 2005
    Location
    Interior Alaska
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    When I learn how to attach pictures I will ask for input.

    LRB

  3. #3
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    Oct 2005
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    Interior Alaska
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    Attached are photos of sub panel I am requested to hook up 2 - 7 1/2 HP 3ph air compressors and air drier.







    Panel has not been in use for over 10 years.

    Only 2- 20 A 1 phase circuits are being utilized.

    The installer used Al 4/0-4/0-2/0 tri plex for 3 ph feeder cable and #4 bare cu for EGC and Neutral. The bare copper is run outside the feeder conduit to a trough above the ceiling, after the trough, there is 2 " EMT running about 75 feet to an electrical room and a 200A transfer switch. Facility was built in 1980 and defaulted to bank. Current owner has owned for about 25 years. I am recommending immediately installing 100 amp fuses in the transfer switch. We know the bare EGC/Neutral will put neutral current on the 2" EMT, I need a powerful worded reason to get them to replace that feeder with correct conductors. Note-a separate part of this building is being utilized as a flour mill, and attached to flour mill is living quarters for the mill manager. This is a large family farm / flour mill. I think I have a powerful argument for the safety and investments of the mill and living facility and family members. to get them to replace this feeder. The air compressors are for pneumatic packageing equipment.

    Any input is appreciated. LRB

  4. #4
    Join Date
    Feb 2004
    Location
    Shelby Twp. MI, near Detroit
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    The pics are so small that I cannot see any detail and can't seem to blow them up. I am not sure what it is you are asking, but i am interested. It sounds like there are a number of violations in the current installation. Are you asking for advice on how to present an argument for why you could not do what they are asking without first correcting those violations or are you trying to work around them?

  5. #5
    Join Date
    Aug 2004
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    Northern illinois
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    I do not think it is code compliant.

    I don't see how it can be made code compliant as is.

    Yank the wiring and run 4 conductors and use the emt as the egc. best you can do.
    Bob

  6. #6
    Join Date
    Oct 2005
    Location
    Interior Alaska
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    Thank you for input petersonra and richwaskowitz. I am reposting pictures.

    Click image for larger version. 

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    Click image for larger version. 

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    Click image for larger version. 

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    I am just figureing out how to post images. Hopefully these can be enlarged

    Yes I want a strong argument for why this feeder "as is" is a safty concern for personnel and equipment. The NEC violations are obvious. To me the undersized "B" phase is potential fire hazard with 200 amp fuses. While the bare neutral/EGC is major violation, in reallity is it any more dangerous than the millions of 3 prong electric driers and ranges in existence?

    Petersora-as constructed, using the EMT for is not an option, because conduit supplying sub panel is PVC. However, when we pull new feeders I will replace it with EMT(it is only about 4' long).

    LRB

  7. #7
    Join Date
    Feb 2004
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    Shelby Twp. MI, near Detroit
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    If the Code violations are "obvious" (which a number of are), what more compelling reason to correct the installation are you looking for? Is someone trying to say that they agree that there are violations but that there is no real danger?

  8. #8
    Join Date
    Aug 2004
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    Northern illinois
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    Quote Originally Posted by richwaskowitz View Post
    If the Code violations are "obvious" (which a number of are), what more compelling reason to correct the installation are you looking for? Is someone trying to say that they agree that there are violations but that there is no real danger?
    do you see a "real" danger here?
    Bob

  9. #9
    Join Date
    Feb 2004
    Location
    Shelby Twp. MI, near Detroit
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    The point I was trying to make is, why would we start to question aspects of the Code by trying to quantify the risk associated with a particular rule? I may not see the danger in supporting a piece of NM cable at 55 instead of 54 inches between staples, but that is the rule. That is all. Slippery slope and all that stuff.

  10. #10
    Join Date
    Feb 2003
    Location
    Massachusetts
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    Quote Originally Posted by petersonra View Post
    do you see a "real" danger here?
    This is a code forum, I suspect most times people are asking questions to learn the code not what each of us thinks is safe.

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