Are Square D 2 Pole Breakers Listed for Interactive Use?

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Tradesmanx

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Some inspectors have suggested there should be an additional fastener for the solar breaker that interconnects the array to the main service panel. NEC 705.12 (E) indicates the fastener can be omitted if the circuit breaker is "listed and identified as interactive." Can someone tell me if a standard 2 pole square D breaker is "listed" as interactive. Also, where can I find that it is "identified" as such?
 
Tradesmanx said:
Some inspectors have suggested there should be an additional fastener for the solar breaker that interconnects the array to the main service panel. NEC 705.12 (E) indicates the fastener can be omitted if the circuit breaker is "listed and identified as interactive." Can someone tell me if a standard 2 pole square D breaker is "listed" as interactive. Also, where can I find that it is "identified" as such?
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That language means the inverter be listed as interactive-not the breaker. There is no requirement to fasten the breaker in this application.
 
Until the OP raised the question I never gave the language in 705.12(E) much thought. But now that I look at it from his take, it does not look very well written.
 
Texie, I think you are right. Now that I re read the language, I can see how it could be read to mean the inverter "power source" is what is required to be listed as interactive. That makes sense. I don't think breakers are identified or listed as "interactive." It would have to be the inverter.
 
There's really not much wrong with the language. Not to go overboard in channeling my 10th grade English composition teacher, but an adjectival clause which begins with 'that' always modifies the noun that comes right before it, which in this case is 'electric power sources'. If the section meant to refer to breakers as interactive (which are not an actual thing under any UL standard AFAIK), then it would say something like: "Circuit breakers that are listed and identified as interactive, when backfed from electric power sources...".

It says what it means, which is as texie explained.
 
texie said:
That language means the inverter be listed as interactive-not the breaker. There is no requirement to fasten the breaker in this application.
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The requirement to separately fasten a breaker has to do with whether or not the connected source could remain energized, after the breaker is pulled off the panel busbar. Such as when you use a branch breaker as a main breaker. Or if you interconnect a generator that could still energize the circuit if the rotor is still spinning. The safety issue of concern is that if you unplug the breaker from the busbar, that the energization could carry through to the busbar plugs of the stab-on breaker.

Grid-tied inverters don't work this way, because the inverter power source is subordinate to the voltage of the grid power source. The inverter looks for a grid within specification first, and then produces a slightly larger voltage to push current onto the grid. By design, the inverter ceases to produce power if the grid is disconnected. This wasn't considered when the rules for separately fastening a backfed breaker were first established, so a separate exception had to be written for grid-tied inverters.

Where you would still see this rule applied in a panel for grid-tied inverters, is a branch breaker as a main breaker of a subpanel combining your inverter outputs. Even though operational current flows through this breaker in the direction of an ordinary load breaker, the initial energization backfeeds it, and meets the physical basis for requiring this separate fastener.
 
Looking at the 2017 NEC 705.12(B)(5) it seems pretty clear that circuit breakers don't need to be fastened if backfed from a listed interactive power source. It would seem to be hard for an AHJ to misinterpret the section.
 
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