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Thread: series rated

  1. #1
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    series rated

    We have a 1600A EATON MDP. There will be a 200a feeder from MDP to a 200a SQD sub panel. IS there anything as far as Series rated equipment is there something we need to look into as far as SCCR? Can different brands of equipment be used in series?

  2. #2
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    Quote Originally Posted by mannyb View Post
    We have a 1600A EATON MDP. There will be a 200a feeder from MDP to a 200a SQD sub panel. IS there anything as far as Series rated equipment is there something we need to look into as far as SCCR? Can different brands of equipment be used in series?
    The proper terminology is not sccr but AIC for circuit breakers and other overcurrent protection devices like fuses. Short circuit current rating indicates the amount of short circuit current a device can take without some specified level of damage. Amps interrupting capacity is how much short circuit current the overcurrent protection device can open.

    There is nothing wrong with using different brands of equipment in series. However it is unlikely that a circuit breaker manufacturer would test their Breakers to work in series with another brand of circuit breakers to give you a higher AIC rating. Fuse manufacturers on the other hand have incentive to do this and often have tested their fuses with multiple manufacturers circuit breakers.

    It would be best to have the engineer that is doing the design work on this project to specify what you need so that it meets both the short circuit current requirements and the arc flash requirements.
    Bob

  3. #3
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    Is the available fault current at the sub panel higher then the rating of breaker(s) at the sub panel? If not you don't need to be concerned about series ratings. If the sub is only a few feet away, you maybe have something to be concerned about. If the sub is 100 feet away - chances might be pretty good the available fault current is low enough just because of the resistance of the feeder conductors, might even be low enough at only 25 - 50 feet away.
    I live for today, I'm just a day behind.

  4. #4
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    But to answer your question directly, no. Nobody does series ratings with competitor's products. Those ratings are attained through very expensive destructive testing and there is zero ROI on one mfr. testing a competitor's products down stream or up stream of their own.
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  5. #5
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    Quote Originally Posted by Jraef View Post
    But to answer your question directly, no. Nobody does series ratings with competitor's products. Those ratings are attained through very expensive destructive testing and there is zero ROI on one mfr. testing a competitor's products down stream or up stream of their own.
    Occasional exception - like Milbank or Midwest meter-main-loadcenter units. Just installed a Milbank recently, factory installed main breaker was a Siemens breaker. Label lists about every 1 inch wide plug on breaker made as acceptable to use for branch breakers.

    But at same time I didn't check to see the AIC rating of the main. If only 10 kA not really anything to be concerned with for series ratings as the typical branch breaker used in these is also 10kA.
    I live for today, I'm just a day behind.

  6. #6
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    A practical example: Once I had to feed a 400 amp panelboard from a I-line MDP. I initially defaulted to square D for the series ratings, but I also got a quote from siemens which was like $400 less. I ran the numbers and the 14k rating on the BQD breakers was ok without any series ratings.
    Ethan Brush - East West Electric. NY, WA. MA

    "You can't generalize"

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