2020 NEC 250.109

[Greentagger]

Would this apply to the requirements of 250.24(A)(1) having the GEC terminate at the grounded conductor bus ? If I’m not mistaken , unless you have a wire type or busbar connecting the grounded conductor buss and the EGC buss, the GEC must terminate at the grounded conductor buss? If a screw type main bonding jumper is installed , the GEC must terminate at the grounded conductor buss. Is the addition of 250.109 allowing the GEC to terminate on a lug attached to the case of the service disconnect enclosure if there is a screw type main bonding jumper installed? Thanks in advance.

 

[don_resqcapt19]

Would this apply to the requirements of 250.24(A)(1) having the GEC terminate at the grounded conductor bus ? If I’m not mistaken , unless you have a wire type or busbar connecting the grounded conductor buss and the EGC buss, the GEC must terminate at the grounded conductor buss? If a screw type main bonding jumper is installed , the GEC must terminate at the grounded conductor buss. Is the addition of 250.109 allowing the GEC to terminate on a lug attached to the case of the service disconnect enclosure if there is a screw type main bonding jumper installed? Thanks in advance.

The rule in 250.109 does not apply to grounding electrode conductors.

This rule was added to actually permit a metal enclosure to serve as part of the equipment grounding path. We have been using the metal enclosures as part of the EGC path forever, but prior to the 2020 code there was nothing in the code that actually permitted that practice.

 

[Little Bill]

The rule in 250.109 does not apply to grounding electrode conductors.

This rule was added to actually permit a metal enclosure to serve as part of the equipment grounding path. We have been using the metal enclosures as part of the EGC path forever, but prior to the 2020 code there was nothing in the code that actually permitted that practice.

I don't know of anything that prohibited it either.

 

[wwhitney]

I don't know of anything that prohibited it either.

2017 250.118 states "The equipment grounding conductor run with or enclosing the circuit conductors shall be one or more or a combination of the following:" and doesn't list metal enclosures. So it was inadvertently prohibited. My PI proposed adding metal enclosures to 250.118, but for some reason the committee preferred to create a new section.

Cheers, Wayne

 

[don_resqcapt19]

I don't know of anything that prohibited it either.

The code rule require various things to be connected to an equipment grounding conductor and we would make a connection to the metal enclosure. There is nothing in the code or the listing standard that says the metal enclosure is an EGC. Sure we have used them as such forever, but there was nothing in the documents that said we could.
Same with the using metal raceways as EGCs and connecting sections of raceways together with a metal box to continue the EGC path. Nothing permitted that either.

There were a number of PIs like the one by Wayne that would have added the metal enclosures to 250.118. Those proposals were all resolved (rejected) at the First Revision Stage. A number of pubic comments received on the issue and CMP 5 choose to create 250.119, in lieu of adding the enclosures to 250.118.

 

[mbrooke]

Tis interesting. Why the rejection?

In my world where a wire EGC is present I typically avoided using the can for continuity- this rule being one of them. Good to know this is now clarified.

 

[Greentagger]

Thank you guys for your input.