[RE-wrenches] NEC 2014 690.12 Rapid Shutdown

[Jeffrey Quackenbush]

Wrenches,

There is no guidance in the Code text for where the shutdown should take place. (1) says: "Requirements for controlled conductors shall apply only to PV system conductors of more than 1.5m (5') in length inside a building, or more than 3m (10') from a PV array."

So, the provisions apply if the circuit 10' from the array and 5' inside a building, but no mention is made of where the shutdown actually needs take place in the circuit. In the video Bill Brooks suggests that the shutdown mechanism should also be placed within this 10'/5' boundary but that is just an inference -- nowhere in the text is this actually specified. If that was the intent of the Code committee, then they've done a poor job actually expressing it in English.

I'm concerned that some AHJs will interpret this to exclude all central inverter systems (without the addition of cost-inducing secondary DC-DC converters like Tigo) because the combiner or junction box can be many feet from the actual beginning of a home run under the array. Alternately, permissive AHJs could allow this function to be fulfilled anywhere, meaning that the implementation won't meet the intent of the writers.

I'm also concerned, as Isaac mentioned, that there are no requirements for how the shutdown be initiated, or that it contains of the accessibility and grouping requirements that are always included for disconnects. I really think this should be treated and categorized as a disconnect requirement, not a circuit requirement, because that is the ultimate function that's intended. 

I'm surprised none of the inverter manufacturers have chosen to comment here, as this could dramatically impact the sales of central inverters.


Jeffrey Quackenbush
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