NEC 690.12 - RSID's for Solar Carport with Inverter AC Output Conductors Run Over a Building to Electrical Room - What Solution will Satisfy 690.12?

[jaggedben]

...There's nothing vague or ambiguous about the definition of "building" in the NEC.

The issue is just that the definition doesn't match the (presumed) expectations the writers of 690.12 had, nor the expectations of the AHJs applying 690.12. ...

In the real world, those statements amount to a contradiction.

 

[ggunn]

I'm more or less with you on your comments except on this point as it relates to 690.12. There's nothing vague or ambiguous about the definition of "building" in the NEC.

The issue is just that the definition doesn't match the (presumed) expectations the writers of 690.12 had, nor the expectations of the AHJs applying 690.12. So that's fine, they can collectively decide that the definition is wrong, or 690.12 is written wrong given the definition, and apply their collective judgement to enforce a more reasonable rule. Or perhaps most often, never even look at the NEC definition of "building" and just use the definition they're used to.

Basically this is just a case of everyone collectively agreeing (perhaps unknowingly) to ignore Charlie's rule. Until someone made a PI for the 2023 NEC for 690.12 that says (I'm guessing, I didn't read it) "hey this doesn't actually say what we've all been thinking it says, so maybe we should fix that."

Given all that, I would say that you're correct in your advice to the OP to just assert in the permit application that the carport is not a building and so 690.12 doesn't apply. And then only if the AHJ pushes back, look to convince them in fact it's not a building because the support structure is all equipment, or to allow the use of not-yet-adopted 690.12 Exception 2, or move the inverter outside the footprint of the carport, or whatever.

Cheers, Wayne

Whatever. We were building PV AC combiners that conform to what is now 705.12(B)(3) before the code allowing them was added to the NEC because requiring them to conform to the "120% rule" was just plain stoopid and everyone knew it. Charlie's Rule notwithstanding, a modicum of common sense is necessary in interpreting the NEC.

Rapid shutdown was brought into the NEC to protect firefighters who are on a roof chopping holes in it to ventilate the building below it. Obviously that won't happen with a parking shade irrespective of whether or not one might interpret the NEC as defining it as a building. Exception 2 merely codifies what we already knew.

 

[wwhitney]

In the real world, those statements amount to a contradiction.

No. "Vague" and "ambiguous" still aren't the correct words to use when there is a mismatch between the NEC definition and the user's expectations. The NEC definition is clear enough. Probably "unexpected" is the best description of the NEC definition of "building". Or depending on your attitude, maybe "stupid" : -)

But anyway, I don't think there's much substantive left to discuss about the use of the word "building" in 690.12. Good to remember that the 2023 NEC added Exception 2.

Cheers, Wayne