NEC 690.12 and 690.13

[wyboy]

I have questions regarding NEC 690.12 and 690.13.

An installation consisting of a house and barn has an array on both structures. The photovoltaic output circuits from the array on the barn feeds through a DC disconnect on the barn then in underground conduit to the inverter in the house. The photovoltaic output circuits from the array on the house feeds to the inverter in the house. (The inverter in the house is not located immediately upon entry.) Rapid shutdown is accomplished by optimizers on the panels and a disconnect by the service.

Question 1: NEC 690.12 requires PVC circuits installed on buildings shall have a method for rapid shutdown. It has no requirements for location. Does the disconnect on the house meet rapid shutdown requirements for the barn?

Question 2: NEC 690.12 requires a disconnect for DC conductors feeding a different building or structure. The rapid shutdown disconnect would certainly kill power from the photovoltaic output circuits from the barn. Does rapid shutdown disconnect meet the requirements of NEC 690.12 or is a separate DC disconnect required where the photovoltaic output circuits from the barn enter the house? If not does the disconnect on the barn meet the requirements?

 

[jaggedben]

I assume we're talking 2014 NEC here. The 2017 is clear on the subject of rapid shutdown switch location.

You ask some interesting questions and I'm not sure there are clear answers. A few thoughts:

- I'm not sure the DC disco on the barn is required. Presumably your DC conductors there aren't connected to any other conductors in the building that they need to be disconnected from.
- If the optimizers are SolarEdge then the DC disco on the barn not only might not meet the rapid shutdown requirements, but it would actually defeat the rapid shutdown function installed in the inverter. I believe you could meet the letter of the 2014 NEC by putting that disco within 10ft of the array, since it's not required to be readily accessible.
- Under the 2014 NEC you're within the letter of the code by having the rapid shutdown on the house. But it's kinda violating the spirit of the whole thing. Suppose the barn is on fire and the house is not. If there's any real distance between then, are firefighters supposed to have to figure out that they have to go to the house to initiate rapid shutdown? I could see an AHJ not letting you get away with that, based on common sense. Or at least requiring very clear placarding.