That was my next question. Had my head in the code book before I looked up to see these responses. (FYI I'm working with the 2011 NEC.)
This transformer will be relocated to the side of an existing woodframe garage. We will provide a new 60A MCB panel within the garage. This panel will in turn feed a couple existing circuits in the garage and two new outbuildings - each of which is small enough to be fed with a single 120V 20A/1P breaker.
Article 250 has changed significantly since I last took a class on service grounding, so let me take my best guess as to what needs to happen.
Start with the outbuildings, they are easy. 250.32 Buildings Supplied by a Branch Circuit. (A) Grounding Electrode. "Exception: A grounding electrode shall not be required where only a single branch circuit supplies the building and the branch circuit includes an equipment grounding conductor." (That's not verbatim but close enough.) So no grounding electrodes required, correct? Just run an equipment grounding conductor to each device and we're good.
Back to the garage: I assume 250.30 is where to start. Looks like I must follow (A)(1) through (A)(8):
(1) System bonding jumper. Required, we will put it at the source.
(2) Supply-side bonding jumper. Required.
(3) Grounded Conductor: Not required as we have a system bonding jumper at the source [see (A)(1)].
(4) Grounding Electrode. Required. (1) and (2) are not available, so exception allows connection to any electrode listed in 250.52(A). I assume a single ground rod (as described in 250.52(A)(5)(b)) at the 480V:240V transformer is acceptable.
(5) Grounding Electrode Conductor. Required. Connect (1) to (4).
(6) Grounding Electrode Conductor, Multiple Separately Derived Systems. Not required.
(7) OK.
(8) No metal, not required.
I am foregoing the disconnect on the primary side of this transformer, as there is a main disconnect on the new panel on the secondary side. The two outbuildings each will have one single-pole main disconnect switch as the service enters the building.
Man, this part of the code is confusing. Getting closer to understanding it. I think I have it right on this project. Please let me know if I am off on something. Thanks!