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Thread: Back fed breakers

  1. #21
    Join Date
    Jun 2006
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    Quote Originally Posted by jaggedben View Post
    Wow, I wouldn't agree with any of that.

    I think that a back-fed plug-in type breaker, for the purposes of of 408.36(D), is simply a breaker that has the supply conductors connected to the terminals, rather than to the busbar that connects to the 'plug in' part. In other words, it's a breaker whose parts can remain energized when the breaker is unplugged, opposite the way that most plug-in type breakers get installed. The requirement is there simply to prevent someone in a hurry from missing the fact that an unplugged breaker could shock and kill them. 705.12(D)(6) overrides that requirement precisely because a utility interactive inverter does not continue to energize the breaker if it's unplugged. It basically recognizes that GTIs aren't a 'supply' for the purposes of 404.36(D), and that the danger doesn't exist.

    The first quote doesn't jive with the second. Multiple breakers used as service disconnecting means in an MLO panel aren't backfed according to your definition in the first quote. I would say they aren't backfed because they are energized from the busbars, hence if unplugged they are no longer energized. (It might be wise in many such installations to have tie downs to prevent accidental movements in the vicinity of high fault currents, but I don't think that 408.36(D) requires it.)

    I've seen plenty of back-fed breakers set up as service disconnecting means. But like ggunn I'm struggling to visualize how such a breaker could fall under 705.12(A).
    I don't believe I need re-educated on what qualifies as a back-fed device. I agree with what you say as far as the requirement is [likely] to prevent inadvertent disconnecting of a back-fed plug-in breaker, so the stabs will not be floating in mid air and energized, not to mention the potential fault created if disconnected under load. In the case of a combination service disconnecting means, GTI disconnecting means breaker, that would not be the case (at least not sustained, as there could still be enough incident energy to establich an arc fault if disconnected under load)... but I essentially agree.

    However, 408.36(D) does not say that. It simply requires back-fed plug-in devices to be secured in place... period ...no elaboration on reason or purpose. So you're either going to have to qualify the PV GTI breaker as not being a back-fed device... or put in on the load side of a service disconnecting means... if you don't want to secure it in place.

    Another option (though compliant implementation will be significantly delayed ) is to propose a change to 705.12(D) so as to include a "modification" for line-side connections, similar to thatof 705.12(D)(6) for load-side connections.
    I'll never get there. No matter where I go, I'm always here.

  2. #22
    Join Date
    Feb 2007
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    Moving OUT!
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    If youreplace a back fed breaker that does not have a hold down are we compelled to install one.

  3. #23
    Join Date
    Dec 2012
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    Placerville, CA, USA
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    Quote Originally Posted by Sierrasparky View Post
    If youreplace a back fed breaker that does not have a hold down are we compelled to install one.
    Unless it is covered by the Utility Interactive exception, I would expect that you would have to. But it might depend on whether the lack of a hold-down was ever code compliant.

  4. #24
    Join Date
    Feb 2013
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    Aspen, Colo, Pitkin County
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    Quote Originally Posted by GoldDigger View Post
    Unless it is covered by the Utility Interactive exception, I would expect that you would have to. But it might depend on whether the lack of a hold-down was ever code compliant.
    The OP does not define the PV system. Stand alone PV system will generally have battery storage to energize the system 24/7 with proper charging or another energy source so -- secured breaker -- interactive PV ssystem cannot send energy to the terminals of the backside without a grid connection IE -- breaker releases from buss would have no energy provided to the terminals. Doesn't give PV special rules. The majority of systems I see are interactive.
    CircuitRyder --- Unfortunately not all good ideas are code enforceable.

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