Isolated grounds

[billdozier 78]

If you have 3 circuits in one conduit all calling for isolated grounds how many do you pull? To me I would pull one eg ground and one ig which would then pass through each box to individual duplex receptacles.1

 

[ActionDave]

That is the way I would do, and have done, it. Unless there is some thing in the specs that says other wise. I have had to to anything other than what you described, but I'm sure there are others who have.

 

[texie]

Seen it done both ways. One could argue that a common isolated grould between the multiple outlets could set up ground loops between them. Also, keep in mind that in any event that the isolated grounds must pass thru (not connected to) any sub panels and connect at the service bonding point. In a commercial setting this can be a bit of a challenge. Other wise they are pretty much useless as isolated ground circuits.

 

[Smart $]

... Also, keep in mind that in any event that the isolated grounds must pass thru (not connected to) any sub panels and connect at the service bonding point. ...

Not an NEC requirement. In fact, the NEC don't require anything different than "regular" EGC's. The NEC just permits IG EGC's to not be connected to normally-non-current-carrying-metal parts along its route.

 

[texie]

Not an NEC requirement. In fact, the NEC don't require anything different than "regular" EGC's. The NEC just permits IG EGC's to not be connected to normally-non-current-carrying-metal parts along its route.

I did not mean to imply that it is a NEC requirement, just that if you don't they are pretty much worthless.

 

[jim dungar]

Also, keep in mind that in any event that the isolated grounds must pass thru (not connected to) any sub panels and connect at the service bonding point.

This would be a design issue, only. The NEC does not describe where isolated grounds begin, or end.

Isolated grounds can be used to create a 'single grounding point' to minimize ground loops for interconnected equipment, as such there is no reason that a 'sub-panel' could not be that point.

 

[ASG]

I did not mean to imply that it is a NEC requirement, just that if you don't they are pretty much worthless.

One can argue that it is a rare instance where isolated grounds aren't pretty much worthless as is.

 

[petersonra]

One can argue that it is a rare instance where isolated grounds aren't pretty much worthless as is.

IMO not worthless.

Electrician gets paid big money to install them. Must be worth at least as much as is being paid out.