[RE-wrenches] NM Cable temp rating, ampacity, application

[eric at harvesthesun.com]

Hi Wrenchers,
 
I recently butted heads with an old school electrician who has been scrutinizing a recent install (fully permitted & PTO'd last year) and I wonder how applicable and valid his concerns are. I'm not interested in an ego war with this guy; I just want to be code-compliant and safe. This sparky (let's call him Karl) has questioned my electrician's (let's call him Dave) use of NM cable on the AC side of the solar install.
 
The first issue that Karl raised was that Dave installed Romex for our supply-side connection, i.e., from our fused disconnect to the Polaris vampire clamps on the feeder conductors between the meter and the main disco. Karl contends that the Romex, by extension off of the utility feeders, is now a service entrance conductor and that NEC Article 334.12 dictates that Romex cannot be used as service entrance conductors. Wondering how you all might interpret this scenario. (note: We have the opportunity to pull new conductors, should the consensus be that we violated the NEC)
 
The second issue is that Dave ran 6AWG Romex from the fused disconnect to the main breaker in the combining subpanel and landed the circuit on a 70A breaker. The inverter circuit is rated at max current of 50A continuous. Karl is telling us that the #6 Romex is rated at 60 degrees and 55 amps. It is my understanding that all NM cable is now rated at 90 degrees. However, I also understand that there may be some merit to Karl's assessment regarding limited ampacity of the 6AWG Romex. Can someone illuminate this issue for me as to whether or not NM cable is rated at 90 degrees AND therefore a 6AWG conductor in NM cable would have a 75A rating?
 
Cheers,
 
Eric
SunHarvest
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