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Thread: AFHA Update

  1. #11
    Join Date
    Feb 2003
    Location
    Wisconsin
    Posts
    9,897
    Quote Originally Posted by charlie b View Post
    I agree, Jim. But if the upstream panel has a category 1 rating, you don't need a calculation to assign category 1 to the new panel. Also, if the upstream panel has a category 2 rating, and you are willing to live with a category 2 for the new panel, once again you don't need a calculation. On the other hand, if the upstream panel has a category 2 rating, but you would prefer to assign category 1 to the new panel, then you will need a calculation. That is all I am saying.
    Charlie,
    This is just your experience, mine is different.

    I have made calculations where simply adding 50' more of conductor raised the downstream to over 4 cal/cm^2 while the upstream was still less than 4. It seems to happen most often using 200A Class RK1 fuses with a starting bolted fault current of less than 5kA.
    Just because you can, doesn't mean you should.

  2. #12
    Join Date
    Mar 2013
    Location
    Rutland, VT, USA
    Posts
    342
    I agree with Jim as I have seen where fault currents are low to begin with at a panel and then downstream of that panel, another panel or disconnect switch has a higher incident energy level due to the low fault current and longer clearing time.

  3. #13
    Join Date
    Dec 2004
    Location
    Windsor, CO NEC: 2017
    Posts
    16,206
    Thanks for the replies. When I passed the original report to a competitor, I got a quote for 30% of the original update quote; I don't make it a habit to shop prices, but felt that the original company was pushing their luck. The competitor was apologizing for his "high price" (the 70% cheaper one) because they would have to build that portion of the one line from scratch using the one line in the original report...

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