Hmm. Re-reading the thread, I may have misunderstood... but then again, I may not have. :huh: Newt will have to clarify...
For better or worse and subject to the failings of my memory, and withholding the name of the AHJ, here's my best recollection of what happened in my case:
We had a smallish (<100kW) PV system to interconnect in a fairly large building. There would have been electrical space (a la the 120% rule) to feed the PV into the MDP through a backfed breaker (which is what we had intended to do), but as it turns out there was not enough physical room to land the breaker on the MDP busbars. The owner did not want to spend the money to add another section to the MDP, so the only way to interconnect was a supply side tap. The feeder from the utility transformer was entirely underground to the MDP and the utility did not want us to land on the transformer, so our only alternative was to land our conductors on the input busbars of the main breaker of the MDP.
Incidentally, the electrical room was interior to the building and not adjacent to an exterior wall and there was no room to put the inverters' AC combiner panel in the electrical room. Moreover, the inverters and combiner were already hung on the outside wall and the conduit and conductors run into the electrical room when it was discovered that the busbars in the MDP did not extend to the top of the MDP enclosure, which meant that the breaker we had intended to put into the MDP could not land on one of the busbars. Bummer.
The conductors from the transformer to the MDP were very large - something on the order of six sets of 500kcmil copper. Our equipment on the outside wall was some 30-40 feet away as the conductor flies. I was concerned about the ramifications of the tap rule, specifically as to what size conductors it would direct us to run from the tap point to our gear, so I went to the AHJ's engineering department for a code interpretation.
They ruled that our equipment did not qualify as a tap under the code and was therefore not bound by the requirements of the tap rule. Running those relatively small unprotected conductors through the building out to our gear made me nervous, though, so although the AHJ did not demand it I put in a fused disco in the electrical room right next to the MDP to protect them.
BTW, I am an engineer, not an electrician, and therefore not as accustomed to dealing with the finer points of code as are a lot of you guys. My decision to place the fused disco in the electrical room was one of common sense and what I considered to be prudence rather than one of code compliance.
That's my story and I'm sticking to it.