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Thread: Kaic Rating

  1. #1
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    Kaic Rating

    I am in need of some tech support.

    I have one 600 amp (MDP) main distribution panel , main breaker 22 kaic

    I have seven 100 amp sub panels in the field, main lug also rated 22 kaic

    I have all the branch circuits breakers rated at 22 kaic.

    My question is how the kaic ratings works here.

    This is how I understand kaic ratings work .(please correct me)

    Main panel main breaker 22kaic

    Sub panel and all branch circuit breakers should be 10 kaic.

    My thinking is that a 1 pole 20a,10kaic breaker would trip before the main breaker 22kaic would.

    Any enlightenment would be great. PG


    Also, what would be a series rated panel ?
    Does this terminolgy change things?

  2. #2
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    The AIC rating has essentially nothing to do with what trips first.
    The AIC rating is the ability for the circuit breaker to interrupt a short circuit without blowing up. It is related to the calculated short circuit current at the bard base don the source fault current.
    Ron

  3. #3
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    Basically you have two systems to think about. Fully rated systems would have every breaker rated at or above the available fault current. "series rated" systems are where systems have been tested and rated where the combination of breakers meets the fault current requirement.
    You can not assume "series ratings". They must be listed by the manufacturer. All breakers won't series rate and series ratings don't cross manufacturers.
    If you are depending solely on ratings to meet requirements and your system rating is "x" then you would need to check any breaker rated below "x" to assure it "series rates".
    For example, a two pole 100 amp breaker might not series rate with your main where a 3 pole 20 might.
    Last edited by augie47; 12-11-09 at 02:36 PM.
    At my age, I'm accustomed to restaurants asking me to pay in advance, but now my bank has started sending me their calendar one month at a time.

  4. #4
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    As Ron pointed out, the AIC rating has nothing to do with how fast a device trips.

    As Gus said, a series rating is where two devices with different AIC ratings have been tested together.

    What you have is a fully rated 22K AIC system.
    What you are asking about is a series rated 22/10K AIC combination.
    Just because you can, doesn't mean you should.

  5. #5
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    Quote Originally Posted by pgordon View Post
    ... Sub panel and all branch circuit breakers should be 10 kaic.
    The part where you went wrong is in the should be issue. It can be, which would make the down stream 10kAIC panels less expensive, but only if series tested together as mentioned above. Having them all rated for 22kAIC is a better choice if the AFC is above 10kA.

  6. #6
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    I do not know who's gear you are using but whoever they are, they should be able to help you with the series rating.

    Makes me wonder if the engineer provided any point to point calculations on the one-line regarding aic. Seems odd to me that the aic would not be knocked down just by virtue of the feeder length from the MDP to the panels.

  7. #7
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    The AIC rating depends on many factors and should be calculated by an engineer. Just because an item is a subpanel does not necessarily mean it should rated less than the main distribution, although it could be. The earlier comments were all spot on. Below find a decent list of series rated items:

    SqD: http://www.cooperbussmann.com/pdf/15...0123439a5..pdf

    GE: http://www.bussmann.com/library/techspec/Ge.pdf

    Cutler-Hammer: http://www.cooperbussmann.com/pdf/c3...d1b2c4102..pdf

    Disclaimer: make sure to check the series rating with the mfg. before installing anything. Series ratings can make your life much easier, but also much more difficult if something gets messed up and you didn't check the specification!

  8. #8
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    Quote Originally Posted by skeshesh View Post
    The AIC rating depends on many factors and should be calculated by an engineer. Just because an item is a subpanel does not necessarily mean it should rated less than the main distribution, although it could be. The earlier comments were all spot on. Below find a decent list of series rated items:

    SqD: http://www.cooperbussmann.com/pdf/15...0123439a5..pdf

    GE: http://www.bussmann.com/library/techspec/Ge.pdf

    Cutler-Hammer: http://www.cooperbussmann.com/pdf/c3...d1b2c4102..pdf

    Disclaimer: make sure to check the series rating with the mfg. before installing anything. Series ratings can make your life much easier, but also much more difficult if something gets messed up and you didn't check the specification!
    And to reiterate, if this all seems too complex just go with the same rating all the way through.

  9. #9
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    Quote Originally Posted by Jraef View Post
    And to reiterate, if this all seems too complex just go with the same rating all the way through.
    And just to reiterate your supplier and who he uses for gear can help with series rating.......... Could save a bunch if you can lower required aic.

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