I am adding a mini split system to my house which currently has a smaller air-conditioning condenser in place. In brief, the house is very old so we opted for a ductless mini-split over trying to increase the size of the current unit to avoid needing to add ductwork. We have a 3/4" EMT conduit that leads outside along the back of the house which had only 2 6AWG wires in THHN insulation.
This allowed us to run 2 more 6AWG wires in the same conduit and stay under the NEC fill requirements. Adding a ground wire would have put us over the conduit fill. The original unit was presumably grounded to the panel via the all metal conduit. We also passed the new wire through the original disconnect (going to the original condenser) to a second disconnect (going to the new unit).
To make sure both units were properly grounded an 8' by 5/8" grounding rod was inserted and attached. I may be able to submit for a tax credit on the unit but I'm not sure if the grounding rod meets building codes. The electrician thought possibly not. This route was chosen to avoid running new conduit out of the house (spacing is very difficult). My questions are, does this (grounding to rod and running wire through a disconnect) meet code? Would it pass a permitting inspection?