250.32 Buildings or Structures Supplied by a Feeder(s)
or Branch Circuit(s).
(A) Grounding Electrode. Building(s) or structure(s) supplied
by feeder(s) or branch circuit(s) shall have a grounding
electrode or grounding electrode system installed in
accordance with Part III of Article 250. The grounding
electrode conductor(s) shall be connected in accordance
with 250.32(B) or (C). Where there is no existing grounding
electrode, the grounding electrode(s) required in 250.50
shall be installed.
Exception: A grounding electrode shall not be required
where only a single branch circuit, including a multiwire
branch circuit, supplies the building or structure and the
branch circuit includes an equipment grounding conductor
for grounding the normally non?current-carrying metal
parts of equipment.
(B) Grounded Systems. For a grounded system at the
separate building or structure, an equipment grounding conductor
as described in 250.118 shall be run with the supply
conductors and be connected to the building or structure
disconnecting means and to the grounding electrode(s). The
equipment grounding conductor shall be used for grounding
or bonding of equipment, structures, or frames required
to be grounded or bonded. The equipment grounding
conductor shall be sized in accordance with 250.122.
Any installed grounded conductor shall not be connected
to the equipment grounding conductor or to the grounding
electrode(s).
there you go no rod necessary. the egc is bonded to the frame and the panel. having unneccessary ground rods can cause other problems. so, the 'just throw money at it' plan is not always the best.