PV String OCPD

[Canton]

Can OCPD/Fuses be mounted in a combiner box on the roof under PV Modules? This is for a micro inverters install with enphase inverters. The question is about the fuses being readily accessible.

 

[Carultch]

Can OCPD/Fuses be mounted in a combiner box on the roof under PV Modules? This is for a micro inverters install with enphase inverters. The question is about the fuses being readily accessible.

That would clearly not be readily accessible, as you'd need to remove obstacles and use a tool to get to them. Even with hypothetical module clamps that could be removed without a tool, that would still require the removal of obstacles, thus not readily accessible. It would still be accessible, because removal of a module is reversible, but not readily accessible. In my opinion, I would recommend against this location. I'm aware that opinions are irrelevant for enforcing code-compliance.

With that in mind, combiners are on rooftops all the time, many of which you need a portable ladder to access. You'd be using a portable ladder anyway to troubleshoot the reason why the fuse blew, but still on principle it isn't readily accessible. There are also plenty of combiners sold with enclosures that require a screwdriver to open. Granted, the practice originated before the tool use clarified the definition of readily accessible, but combiners that need screwdrivers to open are still built today, even when specifically built for NEC2014 and later. So I don't know how this is supposed to square with OCPD's in general needing to be readily accessible.

 

[Canton]

Thanks, I agree that the Fuses/OCPD for the strings need to be readily accessible, 690.9D does not exempt them as they are not PV Source/Output circuits. They are inverter output circuits and must be readily accessible.

 

[Carultch]

Thanks, I agree that the Fuses/OCPD for the strings need to be readily accessible, 690.9D does not exempt them as they are not PV Source/Output circuits. They are inverter output circuits and must be readily accessible.

Enphase also makes the Q-aggregator product that can allow paralleling of multiple inverter branch circuits without OCPD, so that you can travel from the roof with a circuit much larger than 20A. By not having OCPD, the Q-aggregator can be below the module without issue. By being part of a system listed for the specific application, it allows you to avoid the need to put each 20A branch circuit on a dedicated circuit breaker or fuse. The Q-aggregator output would be what then connects to a dedicated circuit.

 

[jaggedben]

The aggregator does have fuses.

 

[Carultch]

The aggregator does have fuses.

I didn't realize that previously. Interestingly enough, Enphase also recommends a location under the modules for where to install it, plus it needs a tool to open it. So somehow, there is an exception for their installations to not require readily accessible fuses with this product.

 

[Canton]

This installation is simply inline fuses in a roof mounted Soladeck box. These are not readily accessible and would be a violation in my opinion.

 

[jaggedben]

This installation is simply inline fuses in a roof mounted Soladeck box. These are not readily accessible and would be a violation in my opinion.

What code section would it be violating? 240.24 refers to 'circuit breakers and switches containing fuses'. That doesn't include what you're describing.

Hmm, I realize I'm quoting language that is revised in the 2020 NEC. So tue code cycle may affect this.

 

[jaggedben]

Hmm, so I don't really know the reasoning behind the word-smithing in 240.24 in the last two cycles, but it seems to me you'd have to be back on the 2014 NEC to call it a violation. Also there is exception 4 which arguably applies here.

What your describing is not an uncommon practice, and without seeing a clearer safety danger or a less ambiguous code section I would not consider this a violation.

 

[Canton]

Hmm, so I don't really know the reasoning behind the word-smithing in 240.24 in the last two cycles, but it seems to me you'd have to be back on the 2014 NEC to call it a violation. Also there is exception 4 which arguably applies here.

What your describing is not an uncommon practice, and without seeing a clearer safety danger or a less ambiguous code section I would not consider this a violation.

Ya, we are still on the 2014. Can't wait to get off of it. Yes, I agree it is a gray area and arguable also.