# Thread: 690 or 705 sections that need changes for the 2020 NEC cycle?

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Originally Posted by Carultch
How about something that eliminates the de-facto requirement to include rounding errors when sizing AC combining panelboards, and allows for minuscule related loads in a dedicated PV system panelboard (DAS, AFCI power, TVSS, convenience outlet), without making a panelboard significantly larger than any real amount of current on it? If a panelboard is ultimately protected by an main OCPD, there's no reason to accumulate all those breaker round-up errors.

For instance, consider 17 qty inverters with 18A operating current, and 25A breakers. 17*25A = 425A. However, if you neglect the fact that you had to round up to 25A breakers, you realize that only 306A worth of current are present in the first place, so all you really should need is 400A.

I'm thinking something like a way to use the 120% rule in reverse, to allow for load breakers. Satisfying both of these criteria.
A. 1.25* total inverter current <= busbar and main OCPD ampacities
B. 1.25*total inverter current + sum of auxiliary load breakers <= 1.2 * busbar ampacity
C. The locations of load breakers are such that load and source currents are in opposite directions on the busbar
I take it this is for 705.12(B)(3)(c). I think we are kind of stuck with that one for making up PV AC combiners. It was a fight just to get it through.

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Originally Posted by pv_n00b
I take it this is for 705.12(B)(3)(c). I think we are kind of stuck with that one for making up PV AC combiners. It was a fight just to get it through.
Do you mean 705.12(D)(2)(3)(c)?

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Originally Posted by ggunn
I would like the NEC to declare one way or the other whether or not an AC disco on a supply side connected PV system needs a neutral to ground bond, with all that entails. Some AHJs say yes, others say no.
So would I. I’ll see what I can bring up to make it more declarative. I’ll tell you though, I’ve brought this up before and some people seem to think it’s clear that it is not a service entrance so they block adding any wording to that effect.

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Originally Posted by ggunn
Do you mean 705.12(D)(2)(3)(c)?
No, but yes. They got rid of B and C in 2017 and the old D is now B.

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Originally Posted by pv_n00b
So would I. I’ll see what I can bring up to make it more declarative. I’ll tell you though, I’ve brought this up before and some people seem to think it’s clear that it is not a service entrance so they block adding any wording to that effect.
Just want to make sure you didn't miss my suggestion in post #5.

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Originally Posted by ggunn
Do you mean 705.12(D)(2)(3)(c)?
That’s the 2014 NEC, we are updating the 2017 version.

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Originally Posted by c_picard
I'll be there next week also. This is near the top of my list.
Cool, please don’t out me in the forum if you happen to find out who I am.

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Originally Posted by Smart \$
I'd like to see a 705 definition of "source tap" aka inverter tap... because it is different than tap as defined in 240.2.

Then differentiate in 705.12(B)(2) requirements for source taps and any modification of 240.21(B) load tap requirements.
Frankly 705.12(B)(2) is hard to deal with and it took so long to even get to this point I’m not sure I have the energy to beat on it more. I’ve talked to people on the CMP about the wording and there is little interest to change it on their side.

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Originally Posted by pv_n00b
Cool, please don’t out me in the forum if you happen to find out who I am.
Ha. Not a noob, we already know that much.

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Originally Posted by c_picard
Ha. Not a noob, we already know that much.
I like being a noob, lowers expectations.

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