Here are a few IG details:
Detail of an Isolated Grounding type Receptacle and Outlet box [with EGC included in
Option #1 shows Isolated Grounding Conductor running back to sub panel which the IG
Receptacle's Branch Circuit is fed from [panel of circuit origin].
I.G. conductor is terminated to an Equipment Grounding Conductor's Bus within this
Sub panel. This would be an Isolation of the Receptacle's Grounding Conductor from the
Outlet Box, to the Sub panel.
Option #2 shows a complete Isolated Grounding System at the Sub panel of the IG
Circuit's Origin. The Sub panel contains an Isolated Grounding Bus, which has no
Electrical Connection to the Sub panel's Metallic Enclosure.
A Dedicated Isolated Grounding Conductor "Feed" is run from the Main Service [or
Transformer of a Separately Derived System], to the IG Bus.
No Electrical Ground Bonding is done at any other point than at the connection of that
System's Grounded Conductor bond to the Grounding Electrode System.
Detail #2a below is an overview.
Detail #2a shows an overview of an IG system on a Utility supplied Power Transformer
type Service and System.
In this detail, the IG "Feeder" is run in the Sub feed Conduit to the Main Service.
If needed, the IG feeder could be run separate from the Sub feed - and if not subject to
possible damage, can be run exposed. Better to run in conduit, so no one does
anything "Stupid" to the IG feeder bond conductor.
The IG Feeder conductor could be sized according to the largest Branch OCPD it would
be used with [typically a 20/1 breaker]. That would mean the IG bonding feeder running
from the IG bus in the Sub panel to the Main Service could be a #12 cu.
Most Designs would specify the use of at least a #8 cu IG feeder bond conductor.
I have normally installed and specified a #6 cu minimum for IG feeder bond.
Branch circuit IG conductors do not need to be "Upsized" for Harmonics, unless there's
reasons to do so.
Say for instance there's Harmonic Filters used with the Equipment that uses IG
Receptacles / Circuits. If many of these are used per multiwire circuits, then upsizing of
the IG conductor would be needed - as would an oversized Grounded Conductor on high
This Image was submitted to me by Joe Tedesco.
[original file name = isolated.jpg]
Thank you very much for the Image, Joe!
This Image shows the details of an Isolated Grounding [IG] type 15 Amp, 125 Volt 2 pole 3 wire Receptacle [NEMA 5-15R] - the most commonly used IG Receptacles.
There are - of course - 20 Amp, 125 Volt 2 pole 3 wire IG Receptacles [I usually prefer to use the 20 amp recepts on high load / use equipment - such as Server Equipment, or where cords will be frequently unplugged / replugged].
Along with 5-15R and 5-20R type IG Receptacles, there are 15 and 20 Amp 250 Volt 2 pole 3 wire and 3 pole 4 wire [125/250 Volt] - which range upto 30 Amps.
Discussion for these items located in the General Discussion area.
posted 11/17/2001 @ 21:17:00
Edit on 11/19/2001 @ 18:21:00 to add new Image, plus remove a few things
[This message has been edited by Scott35 (edited 11-19-2001).]