EGC Required in Conduit?

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BMacky

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Foster City, CA
I am replacing 4 aged panels in a commercial building. All panels are fed from separate overcurrent devices in a cabinet on the exterior of the building. Each panel is fed through either rigid or EMT conduit through the space above a t-bar grid ceiling, and load-end cabinet connections are through concentric knock-outs in the top of the panel.

These panels were dated back to the early '60's and I don't know what Code requirements were back then, but have been searching for any article 250 requirements pertaining to whether or not I need to run a separate EGC through the entire length of conduit run from cabinet to cabinet (switch gear to load end). I am planning on adding grounding bushings and the proper-sized bonding jumper in the individual panels, as none are present and the K.O.s are not fully broken out.

One of the panels is three-phase, and is fed merely with the ungrounded conductors, relying only on the conduit as the ground connection back to the main switch gear.

I do see in 250.8(A)(7) the term "listed assembly", which I suppose could pertain to connectors between conduit sections and related fittings, however I am looking to have one inspection when I am done and to be able to have confidence that I added the proper "upgrades" to the system.

Thanks for any input on this post.

Bob
 
BMacky said:
I am replacing 4 aged panels in a commercial building. All panels are fed from separate overcurrent devices in a cabinet on the exterior of the building. Each panel is fed through either rigid or EMT conduit through the space above a t-bar grid ceiling, and load-end cabinet connections are through concentric knock-outs in the top of the panel.

These panels were dated back to the early '60's and I don't know what Code requirements were back then, but have been searching for any article 250 requirements pertaining to whether or not I need to run a separate EGC through the entire length of conduit run from cabinet to cabinet (switch gear to load end). I am planning on adding grounding bushings and the proper-sized bonding jumper in the individual panels, as none are present and the K.O.s are not fully broken out.

One of the panels is three-phase, and is fed merely with the ungrounded conductors, relying only on the conduit as the ground connection back to the main switch gear.

I do see in 250.8(A)(7) the term "listed assembly", which I suppose could pertain to connectors between conduit sections and related fittings, however I am looking to have one inspection when I am done and to be able to have confidence that I added the proper "upgrades" to the system.

Thanks for any input on this post.

Bob
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What code cycle?
 
Although I am a advocate of equipment grounding conductors, a properly installed metallic conduit system is an acceptable grounding means (250.118). and, as has been expounded on here, superior to a EGC in some respects.
Unless you have a local requirement or an unusual situation, there is no requirement to pull and EGC.
Likewise, if it's a 208v system, bonding bushing are not a requirement.
Both the bushings and the EGC are probably a good idea but they are elective.
 
Last edited:
augie47 said:
Although I am a advocate of equipment grounding conductors, a properly installed metallic conduit system is an acceptable grounding means (250.118). and, as has been expounded on here, superior to a EGC in some respects.
Unless you have a local requirement or an unusual situation, there is no requirement to pull and EGC.
Likewise, if it's a 208v system, bonding bushing are not a requirement.
Both the bushings and the EGC are probably a good idea but they are elective.
Click to expand...

Thanks, Gus.

I am curious now about the exception for 208v that was mentioned??!!

I'd like to know about that. What's the Code article?

Bob
 
Not necessarily an exception. See 250.97.
"standard locknuts and bushings" are noted as not acceptable under 250.92 for service conduits and the in 250.97 for circuits over 250 volts to ground you are referred back to 250.92, however, be sure to read the exception.
 
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