Are you looking for this at outbuildings, shops, detached garages, etc.?
2009 IRC E3607.3 Buildings or structures supplied by feeder(s) or
branch circuit(s). Buildings or structures supplied by
feeder(s) or branch circuit(s) shall have a grounding electrode
or grounding electrode system installed in accordance with
Section E3608. The grounding electrode conductor(s) shall be
connected in a manner specified in Section E3607.3.1 or, for
existing premises wiring systems only, Section E3607.3.2.
Where there is no existing grounding electrode, the grounding
electrode(s) required in Section E3608 shall be installed.
Exception: A grounding electrode shall not be required
where only one branch circuit, including a multiwire branch
circuit, supplies the building or structure and the branch circuit
includes an equipment grounding conductor for
grounding the noncurrent-carrying parts of all equipment.
For the purposes of this section, a multiwire branch circuit
shall be considered as a single branch circuit.
IRC Commentary:
Where two or more buildings are supplied from one
service, each building must have a grounding electrode.
For example, a dwelling has a service supplied
from the power company to service equipment on the
outside of the dwelling and has two 2-pole circuit
breakers as main service disconnects. One 2-pole circuit
breaker serves a feeder run to the panelboard inside
the dwelling, and the other serves a feeder run to
a panelboard at a separate workshop building 100 feet
(30 480 mm) away from the dwelling. Both the dwelling
and the workshop must have a grounding electrode as
described in Section E3608. If there is no grounding
electrode at the workshop, one of the grounding electrodes
listed in Section E3608 must be installed. A
ground rod, concrete encased electrode, or ground
ring could be installed. If water is supplied to the separate
workshop building through metal pipe, an underground
metal water pipe could serve as the grounding
electrode. This section states that the grounding electrode
at the separate building must be connected in
the building disconnecting means in one of the ways
described in the two sub-sections that follow. Note that
Section E3607.3.2 applies only to existing premises
wiring systems. A separate building must have a main
disconnect and not simply a panelboard. A main disconnect
could be a main circuit breaker in the
panelboard that would disconnect all the power to the
panelboard.
A grounding electrode is not required in a separate
building if it is served by only one branch circuit. If a
separate building supplied by only one branch circuit
does not have a grounding electrode, it does not have
to have a ground rod installed. If a metal underground
water pipe is already installed at the building, it does
not have to be bonded to the equipment grounding
conductor of the one branch circuit. A building like a
small tool shed, for example, may have only a light and
receptacle. The equipment grounding conductor run
with the branch circuit conductors is sufficient to
ground any equipment for this separate building. Of
course, a receptacle in a tool storage shed or accessory
building at grade level would require ground-fault
circuit-interrupter protection, but, the grounding conductor
need not be connected to a grounding electrode
such as a ground rod.
