Detached Garage arrays and disconnect requirements

[Jmckibbin]

Hi all,

First post here.. cheers. My question is involving detached garages and disconnects on the detached structure. If say we have an array on both a residential house and a detached garage and use a trench to combine the two systems to a single interconnection point, do we need to have disconnect on the garage to protect it?

More specifically, I'm thinking of Enphase systems (which is what we use)

If there is 1 branch circuit of enphase micros on the garage roof and we run a trench back to a combiner box on the house, do we need to provide a disconnect on the garage per the NEC?

I'm struggling finding anything. I know of the rules for detached garages vaguely.. which I believe is if the garage is fed from a single circuit that there are OCPDs required. Also, I believe that if a garage has a sub-panel with more than 6 throws of the hand then there needs to be a main, otherwise its compliant.

Can anyone help me out?

Thank you.

 

[jaggedben]

I believe you need it. 225.31 and .32. There's no exception that applies.

 

[ggunn]

Hi all,

First post here.. cheers. My question is involving detached garages and disconnects on the detached structure. If say we have an array on both a residential house and a detached garage and use a trench to combine the two systems to a single interconnection point, do we need to have disconnect on the garage to protect it?

More specifically, I'm thinking of Enphase systems (which is what we use)

If there is 1 branch circuit of enphase micros on the garage roof and we run a trench back to a combiner box on the house, do we need to provide a disconnect on the garage per the NEC?

I'm struggling finding anything. I know of the rules for detached garages vaguely.. which I believe is if the garage is fed from a single circuit that there are OCPDs required. Also, I believe that if a garage has a sub-panel with more than 6 throws of the hand then there needs to be a main, otherwise its compliant.

Can anyone help me out?

Thank you.

I always put one irrespective of code; it doesn't cost that much and IMO it's a good idea. There's nothing in the code that disallows it.

 

[Jmckibbin]

I believe you need it. 225.31 and .32. There's no exception that applies.

From 2017 NEC:

225.31 Disconnecting Means. Means shall be provided for disconnecting all ungrounded conductors that supply or pass through the building or structure.
It says "pass through the building or structure," what if it is externally mounted?

225.32 Location. The disconnecting means shall be installed either inside or outside of the building or structure served or where the conductors pass through the building or structure. The disconnecting means shall be at a readily accessible location nearest the point of entrance of the conductors. For the purposes of this section, the requirements in 230.6 shall be utilized.

It says "at a readily accessible location nearest the point of entrance of the conductors," implying that it is interior at the entrance of the conductor. M

.. Exception No 1-4 aren't relevant, I don't think.

 

[jaggedben]

Okay, you might be able to argue that. Keep all the conduit outside where it's visible until it goes into the ground.

I'd probably ask the inspector before building. As ggunn says, it doesn't cost enough to run the risk of them disagreeing.

 

[thekernel]

What about Rapid Shutown?

What about Rapid Shutown?

Hope this isn't considered rude to bring in a related topic on a thread here? I do some installs with a similar arrangement. I'm curious how other folks are interpreting the RSD requirements, whether you can put the RSD on the detached structure (garage) if you have one RSD on the house for another array.

 

[jaggedben]

Hope this isn't considered rude to bring in a related topic on a thread here? I do some installs with a similar arrangement. I'm curious how other folks are interpreting the RSD requirements, whether you can put the RSD on the detached structure (garage) if you have one RSD on the house for another array.

Not sure how code spells it out (2014 and 2017 differ a lot) but I think you need one at each building where you have an array. A detached building could theoretically be miles away.

 

[pv_n00b]

I'm not aware of a requirement for an additional PV disconnect in this situation. If the garage was next to the house with the service disconnect I would probably feel fine without a disconnect. If this were a farm with an garage out of site of the house and the service then I would put in a PV disconnect at the garage. Just because the NEC does not require it does not mean it's not a good idea. The NEC is minimum acceptable level of safety, not the industry standard design guide for a good electrical system.

Now adding an RSS to this changes everything.

 

[shortcircuit2]

Need a grounding electrode system for the detached garage. The disconnect also provides the means to terminate grounding conductors to the GES.