peterlarsen.suntec
Member
- Location
- NC/SC
I started recently with a residential solar installation company in SC. SC implements NEC 2014 July 1st 2016. We are installing mostly large systems for resi (10Kw to 20Kw). Most of our interconnections have been supply side taps in the meter can using self piercing taps on the load side feeders. Result...fail, fail, fail again. Both the utility and inspectors have been failing us. So our design team came up with a solution supposedly accepted by the inspectors and the utility. Here's the solution...Have the utility pull the fuses at the transformer, modify the terminals in the can with bolt on double lugs on the line side and tie in the inverter source circuit. Sounded sketchy to me, I never heard of such a thing. Its such a waste of time waiting for the service interruption and I felt there are better solutions. I called an engineer that I know from the same utility in NC. He said no, that won't be acceptable. He stated " if you are going to tie into the meter can you must use the UL Listed accessory for that make of can. Such as Milbank K4977-int. Another engineer from a co-op said NEVER!
I reached out to some of my associates doing taps for other companies. One, let's call her the Tap Queen, said never ever tie into the meter can. She said pull the meter (get approval to cut the tab) run new line side feeders through a new 12×12×8 and make your tap there. She said "no one can argue with that as long as you observe the 10' rule for taps.
Another, let's call him the Tap King said, " Just tap your supply feeders in the MDP using self piercing taps. "We are doing it on all of our installs regardless of size, Its quicker!" Is this solution a violation of NEC 312.8.
Also I read an article on 705.12(D)(2) "Junction box blog" and I can't see where any options are acceptable without "primary source OCP" there is no way to calculate the ampacity of the portion of the supply feeders on the load side of the inverter output connection according to 705.12(D)(2)(1)(a). Do we use the transformer fuse rating?
Thanks for your input.
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I reached out to some of my associates doing taps for other companies. One, let's call her the Tap Queen, said never ever tie into the meter can. She said pull the meter (get approval to cut the tab) run new line side feeders through a new 12×12×8 and make your tap there. She said "no one can argue with that as long as you observe the 10' rule for taps.
Another, let's call him the Tap King said, " Just tap your supply feeders in the MDP using self piercing taps. "We are doing it on all of our installs regardless of size, Its quicker!" Is this solution a violation of NEC 312.8.
Also I read an article on 705.12(D)(2) "Junction box blog" and I can't see where any options are acceptable without "primary source OCP" there is no way to calculate the ampacity of the portion of the supply feeders on the load side of the inverter output connection according to 705.12(D)(2)(1)(a). Do we use the transformer fuse rating?
Thanks for your input.
Sent from my LGLS991 using Tapatalk