From IEEE 1000, Recommended practices on Powering and Grounding Electronic Equipment
8.5.3.2 Insulated ground configuration
The insulated ground configuration also uses an insulated EGC, typically green in color with yellow stripe,
run with the phase, neutral, and standard EGCs from the electronic load equipment to the equipment
grounding terminal of the power system or separately derived system. As opposed to the standard equipment
grounding configuration, this additional insulated EGC typically connects the insulated ground receptacle
(IGR) only to the equipment grounding terminal or bus of the power system source or separately derived
system. This EGC extends radially downstream to the chassis of the electronic load equipment without
contacting any grounded metal surfaces such as metal conduits and raceways, panelboards, and outlet boxes
for receptacles (see Figure 8-17 and Figure 8-18). When this equipment grounding configuration is used, the
enclosing metal raceway must still be properly grounded. This type of equipment grounding configuration is
only intended to be used for reducing common-mode electrical noise on the electronic load equipment
circuit as described in the NEC. It has no other purpose and its effects are variable and controversial. The
use of the traditional orange-colored insulated grounding receptacle for the express purpose of identifying
computer grade power is not allowed per the NEC. If unacceptable EMI is found to be active on the circuit,
an insulated grounding receptacle circuit may be considered as one potential mitigation method. Robust
design of the electronic load equipment for immunity to disturbances on the grounding circuit is another
method. Particularly for distributed computing and telecommunications electronic loads, using optical
signaling interfaces reduces susceptibility to disturbances on the grounding circuit.
We don't use them where I work, we just make sure we have an NEC compliant grounding system.
