Isolated ground receptacles?

[p051981]

I am having some problem understanding isolated ground receptacle. when you install an isolated ground recep., do you have to take that ground all the way back to the panel by itself?

 

[don_resqcapt19]

It has to run back with the circuit conductors, not by itself.

 

[p051981]

thanks for the answer! I guess it was something simple but i jus made it complicated.

 

[charlie b]

Actually, it is simpler, or even more complicated, than that, depending on your perspective. It doesn't "HAVE TO" do anything. We are "allowed to" do something, if the customer wants it.

We may run a ground wire from the end device all the way back to the service panel (or first panel in a separately derived system), without connecting that ground wire to the ground bus on any intermediate panel. It does have to run with the other phase and grounded and EGC conductors, as Don said, and that includes the branch circuit conductors and the feeder conductor(s) to the intermediate panel(s).

 

[mdshunk]

Let me tell you what the low bidder does when the spec is to install some isolated ground receptacles... he runs the circuit just like any other circuit, then he installs a jumper between the box and the ground screw on the receptacle. Some specs only require isolated ground receptacles, but not to actually circuit it as isolated ground.

 

[chris kennedy]

Lately I have been running into IG speced in patient care areas by EE's that have not read this.

517.16 Receptacles with Insulated Grounding Terminals.
Receptacles with insulated grounding terminals, as permitted in 250.146(D), shall be identified; such identification shall be visible after installation.
FPN: Caution is important in specifying such a system with receptacles having insulated grounding terminals, since the grounding impedance is controlled only by the equipment grounding conductors and does not benefit functionally from any parallel grounding paths. This type of installation is typically used where a reduction of electrical noise (electromagnetic interference) is necessary and parallel grounding paths are to be avoided.

 

[glene77is]

... he runs the circuit just like any other circuit, then he installs a jumper between the box and the ground screw on the receptacle.
Some specs only require isolated ground receptacles,
but not to actually circuit it as isolated ground.

Did I miss something here about the "INTENT" of the specification?

I realize that some electricians cut cost by short-cuts.
Surely you are not suggesting that this is acceptable?

BTW, I like your frequent responses in this forum.

...

 

[chris kennedy]

Did I miss something here about the "INTENT" of the specification?

Probably not.

250(96)(B) Isolated Grounding Circuits. Where installed for the reduction of electrical noise (electromagnetic interference) on the grounding circuit, an equipment enclosure supplied by a branch circuit shall be permitted to be isolated from a raceway containing circuits supplying only that equipment by one or more listed nonmetallic raceway fittings located at the point of attachment of the raceway to the equipment enclosure. The metal raceway shall comply with provisions of this article and shall be supplemented by an internal insulated equipment grounding conductor installed in accordance with 250.146(D) to ground the equipment enclosure.
FPN: Use of an isolated equipment grounding conductor does not relieve the requirement for grounding the raceway system.

 

[JJWalecka]

Is there such thing as an Isolated ground GFCI?


JJ