705.12 (D) (1)

Vines

Member
Location
Santa Cruz, CA
I have a couple inspectors in San Jose and Fremont that are now enforcing a requirement that I hadn't seen before.

According to the 2014 section 705.12 (D) (1) the inspector is saying that all of our PV circuits must be able to be disconnected by a single means. In this case, we have 2 strings of AC-PV modules terminating right into the main service. The inspector is calling us out saying we need a subpanel to combine all the circuits and a single dedicated means of disconnect (Breaker or Bladed AC disco), instead of the 2 breakers we currently have.

With the prior generation of enphase, we always put in a subpanel to combine the PV circuits and to reduce the noise in the subpanel so the motioning would work smoothly.

Now that we are using Sunpower AC-PV we aren't having noise issues so want to land our circuits in the Main panel where possible.

For the last year or so the number of disconnects hadn't been an issue, but now 2 inspectors in the same day have had the same comment, so it was likely in a recent training that they learned this.

Looking through my code book I am trying to challenge this, if it is a reasonable challenge. I am curious as to the experience of others. So far looking at 690.17, seems to indicate that up to 6 Circuit Breakers is ok, though it seems to be talking about DC conductors. 690.13 (D) indicates we are ok using molded case circuit breakers.
 

jaggedben

Senior Member
I think your best bet is to ask them to look at the 2017 language and the substantiation for it. 2017 changes 'The' back to 'Each', as it was in the 2011 code.

It was public input 4015 to the 2017 code and can be found on page 6236 (yes, it's a large document) at this link:
https://www.nfpa.org/Assets/files/AboutTheCodes/70/70_A2016_NEC_FD_PIResponses.pdf

The new (or restored) 2017 language reads:

(1) Dedicated Overcurrent and Disconnect.
Each source interconnection of one or more inverters installed in one system shall be made at a
dedicated circuit breaker or fusible disconnecting means.
The substantiation was stated thusly:

Changing the word “The” to “Each” minimizes the possibility of an interpretation of this requirement to mean that
only one (1) PV interconnection is allowed for all inverters on a single existing premises wiring system.
You might also note that from the official NPFA publications it is completely unclear how and why the word 'Each' got changed to 'The' in the first draft of the 2014 NEC. That change was not part of any public input and there is no substantiation for it on record. The 2017 change back to 'Each' seems to be a corrective to what was basically an editing error with unintended consequences, such as you are experiencing.

With that context, hopefully you can get them to accept that each branch circuit is 'one system' and can each have a dedicated breaker. After all, each would operate on its own without the others, and the definition of a system isn't clear enough to dispute that.
 

shortcircuit2

Senior Member
Location
South of Bawstin
I think your best bet is to ask them to look at the 2017 language and the substantiation for it. 2017 changes 'The' back to 'Each', as it was in the 2011 code.

It was public input 4015 to the 2017 code and can be found on page 6236 (yes, it's a large document) at this link:
https://www.nfpa.org/Assets/files/AboutTheCodes/70/70_A2016_NEC_FD_PIResponses.pdf

The new (or restored) 2017 language reads:



The substantiation was stated thusly:



You might also note that from the official NPFA publications it is completely unclear how and why the word 'Each' got changed to 'The' in the first draft of the 2014 NEC. That change was not part of any public input and there is no substantiation for it on record. The 2017 change back to 'Each' seems to be a corrective to what was basically an editing error with unintended consequences, such as you are experiencing.

With that context, hopefully you can get them to accept that each branch circuit is 'one system' and can each have a dedicated breaker. After all, each would operate on its own without the others, and the definition of a system isn't clear enough to dispute that.
Great (time consuming) explanation :thumbsup:
 

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems
I have a couple inspectors in San Jose and Fremont that are now enforcing a requirement that I hadn't seen before.

According to the 2014 section 705.12 (D) (1) the inspector is saying that all of our PV circuits must be able to be disconnected by a single means. In this case, we have 2 strings of AC-PV modules terminating right into the main service. The inspector is calling us out saying we need a subpanel to combine all the circuits and a single dedicated means of disconnect (Breaker or Bladed AC disco), instead of the 2 breakers we currently have.

With the prior generation of enphase, we always put in a subpanel to combine the PV circuits and to reduce the noise in the subpanel so the motioning would work smoothly.

Now that we are using Sunpower AC-PV we aren't having noise issues so want to land our circuits in the Main panel where possible.

For the last year or so the number of disconnects hadn't been an issue, but now 2 inspectors in the same day have had the same comment, so it was likely in a recent training that they learned this.

Looking through my code book I am trying to challenge this, if it is a reasonable challenge. I am curious as to the experience of others. So far looking at 690.17, seems to indicate that up to 6 Circuit Breakers is ok, though it seems to be talking about DC conductors. 690.13 (D) indicates we are ok using molded case circuit breakers.
Some AHJs limit PV to one and only one point of interconnection, i.e., a single disconnecting means, irrespective of any argument you raise from NEC considerations. They would be within their rights to do so, but ask to see it in writing in their interconnection guide if they have one.
 

jaggedben

Senior Member
Some AHJs limit PV to one and only one point of interconnection, i.e., a single disconnecting means, irrespective of any argument you raise from NEC considerations. They would be within their rights to do so, but ask to see it in writing in their interconnection guide if they have one.
Fair point in general, although in this case I think these AHJs won't be making their argument from anything but code. Speaking from specific experience with the ones he mentioned.
 

pv_n00b

Senior Member
Location
CA, USA
Some AHJs limit PV to one and only one point of interconnection, i.e., a single disconnecting means, irrespective of any argument you raise from NEC considerations. They would be within their rights to do so, but ask to see it in writing in their interconnection guide if they have one.
It's a tough case, technically in California a building department AHJ has to go through a local adoption process to modify the code accepted by the state. San Francisco, for instance, has their own electrical code based on the state electrical code. This keeps local inspectors and plan checkers from making up rules on the spot to disadvantage particular contractors or projects. If they don't then they can't legally make something a requirement. The problem is the time and effort required from a contractor to overturn this behavior when it happens. Many just comply to get the project completed and move on.

Municipal utilities, on the other hand, can pretty much make up anything they want other than to just refuse to interconnect.
 

Vines

Member
Location
Santa Cruz, CA
I think your best bet is to ask them to look at the 2017 language and the substantiation for it. 2017 changes 'The' back to 'Each', as it was in the 2011 code.

It was public input 4015 to the 2017 code and can be found on page 6236 (yes, it's a large document) at this link:
https://www.nfpa.org/Assets/files/AboutTheCodes/70/70_A2016_NEC_FD_PIResponses.pdf

The new (or restored) 2017 language reads:



The substantiation was stated thusly:



You might also note that from the official NPFA publications it is completely unclear how and why the word 'Each' got changed to 'The' in the first draft of the 2014 NEC. That change was not part of any public input and there is no substantiation for it on record. The 2017 change back to 'Each' seems to be a corrective to what was basically an editing error with unintended consequences, such as you are experiencing.

With that context, hopefully you can get them to accept that each branch circuit is 'one system' and can each have a dedicated breaker. After all, each would operate on its own without the others, and the definition of a system isn't clear enough to dispute that.
That is great information, than you so much for your insightful response!

In this case it is definitely not a municipal utility requirement, CPAU for instance requires a single bladed locakble AC disconnect. PGE only requires same in specific circumstances where removing the meter will not cut power to the house, or where the meter is larger than a CL 320 unit.

I will provide this information to the code official and see if we can get any traction.
 
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