Results 1 to 10 of 10

Thread: fused main

  1. #1
    Jerome W. Young's Avatar
    Jerome W. Young Guest

    Default fused main

    2 400 amp fuses- 2 sets of 2/0 aluminum service cables- multi tapped in the service lugs.
    Looks like it is over fused correct?

    Similar Threads:
    ***IMPORTANT*** You Need To Register To View Images ***IMPORTANT*** You Need To Register To View Images
    Member Benefits1

  2. #2
    Join Date
    Mar 2007
    Location
    Ormond Beach, Florida
    Posts
    26,248

    Default Re: fused main

    Residential?

    2/0 aluminum is rated for 150 amps. In parallel that would be 300 amps.

    The question becomes, and you probably would not be able to read what is on the terminals without de-energizing everything, but you might also (should also) find in on the label, are those terminals rated for two conductors?

    Some are, most are not.

    Thus I would address it as two parallel 2/0 aluminum conductors for a combined rating of 300 amp which are two small for the 400 amp fuses which are installed, while correcting this, verify that the terminals are rated for two conductors, correct as required.

    The other problem I see is only one neutral service entrance conductor for the paralleled hot service entrance conductors, there should be two neutrals, one run with each set of paralleled hot conductors. Is there another neutral service entrance conductor? if it is in the lower neutral terminal, where is the neutral for the feeder conductor?

    In looking at the larger conductors going vertically on the left, I see four hots (two set paralleled) but only ONE neutral ... that does not bode well for what I think is there.

    Are ALL those service entrance in one conduit? Then derating would also need to be done.

    That photo just begs more questions than it provides answers to.

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  3. #3
    Join Date
    Apr 2009
    Location
    NY State
    Posts
    440

    Default Re: fused main

    Yup. There is more there than the overfuse issue going on there as Jerry mentioned.

    I can tell you with certainly that those terminals are NOT rated for two conductors. That is a biggie right there.

    The lone neutral conductor is the other.

    Is that a 3-phase commercial service?


  4. #4
    Join Date
    Mar 2007
    Location
    Ormond Beach, Florida
    Posts
    26,248

    Default Re: fused main

    Quote Originally Posted by Speedy Petey View Post
    I can tell you with certainly that those terminals are NOT rated for two conductors. That is a biggie right there.

    Peter,

    How can you tell "with certainly that those terminals are NOT rated for two conductors"?

    Is it because the two conductors are side-by-side instead of one-over-the-other?

    Most terminals I've seen rated for two conductors were configured that the conductors fit into the terminal one-over-the-other.

    However, the conductors could still have been installed side-by-side when smaller than maximum size conductors.

    So ... what is the give away that you know those terminals are not rated for two conductors in each?

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  5. #5
    John Steinke's Avatar
    John Steinke Guest

    Default Re: fused main

    Time to gat some "Calibrated eyeballs."

    I have not yet seen a lug rated for more than one 'not' wire under a screw; the multiple-wire lugs I've seen either have completely separate holes/screws for each wire, or a clamp that grips each wire separately from the other.

    More important, that disconnect does not appear large enough to have a 400 apm rating.


  6. #6
    Join Date
    Mar 2007
    Location
    Ormond Beach, Florida
    Posts
    26,248

    Default Re: fused main

    Quote Originally Posted by John Steinke View Post
    I have not yet seen a lug rated for more than one 'not' wire under a screw; the multiple-wire lugs I've seen either have completely separate holes/screws for each wire, or a clamp that grips each wire separately from the other.
    John,

    Same here for a long time, then I saw a photo of one which had an elongated terminal opening (not circular, more like two overlapping circular openings) which was rated for 1-2 conductors, maybe 1/0 or larger in size (don't remember those specifics).

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  7. #7
    Join Date
    Apr 2009
    Location
    NY State
    Posts
    440

    Default Re: fused main

    Jerry, just experience I guess. I have seen and wired enough lugs like that to know that is a single wire termination. There is no way that one is rated for two. I'd easily bet money one it.

    John, if the disconnect will accept 400A fuses it would have to be rated for at least 400A. There is no way you can physically fit 400A fuses into a 200A disconnect.


  8. #8
    Jim Katen's Avatar
    Jim Katen Guest

    Default Re: fused main

    Quote Originally Posted by Jerry Peck View Post
    John,

    Same here for a long time, then I saw a photo of one which had an elongated terminal opening (not circular, more like two overlapping circular openings) which was rated for 1-2 conductors, maybe 1/0 or larger in size (don't remember those specifics).
    Perhaps you're remembering these.

    - Jim Katen, Oregon

    ***IMPORTANT*** You Need To Register To View Images ***IMPORTANT*** You Need To Register To View Images

  9. #9
    Join Date
    Mar 2007
    Location
    Ormond Beach, Florida
    Posts
    26,248

    Default Re: fused main

    Jim,

    Thanks, that looks sort of like what I am remembering, what is the rating on those, I cannot read them in the photos.

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  10. #10
    Jim Katen's Avatar
    Jim Katen Guest

    Default Re: fused main

    Quote Originally Posted by Jerry Peck View Post
    Jim,

    Thanks, that looks sort of like what I am remembering, what is the rating on those, I cannot read them in the photos.
    I am ashamed to say that I never made a note of the rating and I've since forgotten it.

    - Jim Katen, Oregon


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
  •