(206) 949-5683, Top Rated Plumber, Seattle
Results 1 to 5 of 5

Thread: 800a service

  1. #1
    In the Trades mattbee24's Avatar
    Join Date
    Mar 2007
    Location
    Fremont, OH
    Posts
    100

    Default 800a service

    Not sure if anyone can help, but here it goes.
    I have a customer who is installing an 800a commercial service. He ran (2)500mcm copper wires for each leg of the service out of the ct cabinet and up the mast for the power company's (AEP) connection. Now they are telling him he needs to get 4"x8" x 1/4"thick copper plates and drill holes in them for lugs. The power company with then attach their own lugs to the plate to finish the connection.
    Has anyone ever heard of such a thing? I was always told that all you have to do is leave the wire out of the mast and they handle it from there.

    Thanks,
    Matt

  2. #2
    In the Trades Bob NH's Avatar
    Join Date
    Oct 2005
    Location
    New Hampshire
    Posts
    3,307

    Default

    We don't have all of the information but the copper plates may be the least of his problem.

    500 MCM in a raceway is rated at 380 amps at 75C and most terminals are rated at 75C, not 90C. Two of them come to 760 Amps.

    If he has them all in one raceway, they must be derated to 80% of the 90C rating of 430 Amps, or 80% of 860 Amps for the pair, which is 688 Amps.

    If they are in free air the ampacity is much higher and would be adequate.

  3. #3
    In the Trades mattbee24's Avatar
    Join Date
    Mar 2007
    Location
    Fremont, OH
    Posts
    100

    Default

    The size of the wire is not in question here. The power company allows 500mcm for 400a and parallel runs of 500mcm for 800a. And, for some ungodly reason, the power company doesn't have to follow code.
    My question is, has anyone ever came across this with the power company before? Usually, they make the connections before the mast. This is the first time I have ever heard of them requiring you to "make" something up for the wire connections.

  4. #4
    Electrical Contractor/Instructor jwelectric's Avatar
    Join Date
    Jun 2007
    Location
    North Carolina
    Posts
    2,523

    Default

    Quote Originally Posted by Bob NH
    500 MCM in a raceway is rated at 380 amps
    240.4(B) Devices Rated 800 Amperes or Less. The next higher standard overcurrent device rating (above the ampacity of the conductors being protected) shall be permitted to be used, provided all of the following conditions are met:

  5. #5
    DIY Senior Member BrianJohn's Avatar
    Join Date
    Jun 2007
    Location
    VA
    Posts
    151

    Default

    The utilities have their own standards and codes. AS for the 1/4" bus if that is in their Standards for Utility Service (their requirements for service) then you have to doi it. Each utility has their own requirements.

    1/4"X4"=1000 amps, standard bus available from the same company that makes custom troughs and pull boxes in most jurisdictions I have worked in.
    Last edited by BrianJohn; 10-16-2007 at 08:22 PM.

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •