IG systems and NEC code

[AllServicesElectrical]

I got this job at a company with virtually no experience (2 months of service work )in the electrical field. So my boss thought it would be smart to put my solely in charge of acquiring electrical permits for some of the work we are doing. My point being, please dumb this down for me I am still learning.

How do I properly install IGR (isolated ground receptacles) up to code. They are in a drop ceiling and fed from a sub panel. As for the ground bar for the isolated ground, can it be in the sub panel or do i have to run a green and yellow wire through a pipe to the main panel and install a bar there? (there is already 12/2 being used, so medical grade mc would be nice but at this point it isn't practical... or is it?) Also, I don't get how the new bar is isolated if it is connected to the box... isn't the box grounded all the same? Anyways thanks for you time.

 

[infinity]

IG systems are a design issue so there really isn't any guidance from the NEC because it doesn't really care how they're installed as long as they don't violate the "normal" EGC requirements.

As a design the IG should extend all the way back to the point where the main bonding jumper (service) or system bonding jumper (transformer) are installed. Along the way the IG should not be connected to anything which is what makes it isolated. If you want you can install an additional EGC bus in the panel solely for the IG('s) which would be insulated from the enclosure and connected only to the branch circuit IG's and the IG conductor running back to the point where the bonding jumper is installed.

 

[charlie b]

How do I properly install IGR (isolated ground receptacles) up to code?

By way of clarifying (or is it clouding?) the issue, the NEC has no requirements related to IGRs. Rather, it approaches them from the opposite direction. It says that we are allowed to install a receptacle for which the third (i.e., round) hole is not connected internally to the yoke, and thus would not be connected to the metal box. It says we can run a wire from the green screw to the main service panel, without landing it on any ground bar on any intervening panel.

They are in a drop ceiling and fed from a sub panel.

How do you plan to mount a receptacle in a drop ceiling? Those things tend to be a bit flimsy, and I don't know of any good ways that an outlet box can be supported by them.

. . . or do i have to run a green and yellow wire through a pipe to the main panel and install a bar there?

I trust you would be planning to run that wire in the same conduit(s) that contain the branch circuit conductors and (if applicable) the feeder wires. I don't think it can be run in a separate pipe (conduit).

 

[Smart $]

.... I don't think it can be run in a separate pipe (conduit).

...or cable.

It cannot... unless a non-metallic wiring method is used for all circuit conductors.