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Thread: Feeder tap on parallel conductors

  1. #1
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    Feeder tap on parallel conductors

    I am planning on a feeder tap located inbetween the main breaker and the busbar in a switchgear. The load side of the main breaker is field wired with parallel conductors. I wanted to confirm I need to run parallel conductors off the feeder taps to the line side of my fused disconnect, correct?

    The main breaker and service is rated for 600A (not exactly sure the size of the parallel conductors off main breaker) and my fuses will be 300A. I am thinking 1/0 copper or 3/0 al parallel conductors to the line side of my fused disconnect from the feeder tap, does this sound right?

  2. #2
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    I'm assuming your feeder tap is for PV, since you put this in the PV forum.

    You don't necessarily to run parallel conductors to your new disco, but you do need to tap both of the feeder conductors. All conductors of a phase should be terminated at the tap point. For example, I think you might use a Polaris type terminal block with enough positions for both existing parallel conductors, plus however many new conductors you decide upon.

    You also need a new OCPD at the busbar, unless it's rated 900A.

  3. #3
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    Quote Originally Posted by jaggedben View Post
    You also need a new OCPD at the busbar, unless it's rated 900A.
    Code reference?
    Ethan Brush - East West Electric. NY, WA. MA

    "You can't generalize"

  4. #4
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    Quote Originally Posted by electrofelon View Post
    Code reference?
    In the 2017 NEC it would be 705.12(B)(2)(1), if I recall correctly.

  5. #5
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    Yes, right. I will need a new OCPD inbetween the feeder tap and the busbar. It is currently a 600A service and main breaker.

    So here is what I am proposing then (thanks for reminding me).

    Make tap on load side of main breaker (600A) and add a 600A OCPD (maybe fused disconnect) on line side of busbar but load side of tap. That would be in conformance with NEC, correct?

  6. #6
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    Quote Originally Posted by electro7 View Post
    Yes, right. I will need a new OCPD inbetween the feeder tap and the busbar. It is currently a 600A service and main breaker.

    So here is what I am proposing then (thanks for reminding me).

    Make tap on load side of main breaker (600A) and add a 600A OCPD (maybe fused disconnect) on line side of busbar but load side of tap. That would be in conformance with NEC, correct?
    If I understand correctly what you are saying, no, not unless your busbars are rated at 600A plus 125% of your inverter Imax. Make your PV connection on the line side of the main breaker.

  7. #7
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    Quote Originally Posted by electro7 View Post
    Yes, right. I will need a new OCPD inbetween the feeder tap and the busbar. It is currently a 600A service and main breaker.

    So here is what I am proposing then (thanks for reminding me).

    Make tap on load side of main breaker (600A) and add a 600A OCPD (maybe fused disconnect) on line side of busbar but load side of tap. That would be in conformance with NEC, correct?
    I think that conforms, yes. I think ggunn isn't understanding what you're proposing. A connection on the line side of the main breaker might be a better option though.

  8. #8
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    Quote Originally Posted by jaggedben View Post
    I think that conforms, yes. I think ggunn isn't understanding what you're proposing. A connection on the line side of the main breaker might be a better option though.
    I got that he was proposing a load side tap with a 600A disco between the 600A OCPD and busbars of an MLO panel. That would make something approaching 1200A available to the busbars. What am I missing?

  9. #9
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    Quote Originally Posted by ggunn View Post
    ... What am I missing?
    The second 600A OCPD that he proposed to put between the tap and the busbars.

  10. #10
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    Quote Originally Posted by jaggedben View Post
    The second 600A OCPD that he proposed to put between the tap and the busbars.
    Well, that's very different, isn't it? Never mind.

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