At my home I have a detached garage which has sorely needed to have its single branch circuit upgraded to a proper underground feeder, subpanel, the whole works. I didn't want the grounding electrode conductors out flapping in the breeze and thought it would look nice and be better protected too if I run them through EMT down to the soil. That's where I ran afoul of NEC 250.64(E)(1). I need some help figuring out how to do it right.
The code states "Ferrous metal raceways and enclosures for grounding electrode conductors shall be electrically continuous from the point of attachment to cabinets or equipment to the grounding electrode and shall be securely fastened to the ground clamp or fitting. Ferrous metal raceways and enclosures shall be bonded at each end of the raceway or enclosure to the grounding electrode or grounding electrode conductor to create an electrically parallel path." Now, I could just use PVC instead of ferrous and avoid all this, but that wouldn't look nice next to the shiny new RMC risers!
Here at the main panel I had enclosed the GECs in EMT conduit but had to remove it and leave the GECs exposed to partly-pass inspection and get utility power re-connected. There are two GEC because I installed two ground rods with a separate wire to each. At point A there's a 3/4" knockout so I believe I can use a set-screw connector and a lock nut to bond an EMT to the panel. Is that sufficient? The other end of the conduit, where GECs would exit at point B, must also be bonded to the GEC. Can I bond to just one of the GECs, or must bond to both? (Maybe I should eliminate one of them.) What is the name of the bonding connector I'd use at B?
The other end is much more complicated. Conduit comes out of the ground, LB and a conduit stub to get through the wall to a 10x10x4 box, then 2" EMT rising up to the subpanel. At point C in the subpanel I need an insulated grounding bushing because there's an eccentric knockout which impairs the conduit bond to the panel. Does the GEC have to be connected to the bushing, or can I just install a #6 jumper wire from bushing to ground bar in the panel?
At D the EMT connector goes into a (slightly oversized) hole cut in the box; does that qualify as bonded? At E there's a set screw connector in a right-size hole. Is that sufficient? Then there's F, the LB fitting. How does the LB get bonded? (Actually.. it is probably be non-ferrous, so maybe it is exempt). Finally at G I'll need the same connector as at B.
Switching to PVC would be so much easier, but.. if there's a reasonable way of getting it done to meet code with metal raceway I'd like to attempt it. That LB is in full sun and a PVC LB would start looking awful real quick.