Failed inspection "communications not grounded"

[ActionDave]

No, the wording prior to 05 strictly limited it to EGC's. You may be thinking about Gray, in earlier cycles it could have been used as an ungrounded conductor, "natural grey" was used when describing a neutral.

Don gave the details that I was talking about. It wasn't until 2017 or 2020 that the code said we could use a metal box as part of the equipment grounding path when using metal conduit for an EGC.

 

[electrofelon]

It wasn't until 2017 or 2020 that the code said we could use a metal box as part of the equipment grounding path when using metal conduit for an EGC.

Interesting, I never thought about that. Where is it, in 250.118?

 

[ActionDave]

250.109 Metal Enclosures
Metal enclosures shall be permitted to be used to connect bonding jumpers or equipment grounding conductors, or both, together to become a part of an effective ground-fault current path. Metal covers and metal fittings attached to these metal enclosures shall be considered as being connected to bonding jumpers or equipment grounding conductors, or both.

 

[wwhitney]

Interesting, I never thought about that. Where is it, in 250.118?

I first noticed the oversight and put in a PI to add metal boxes to 250.118. [IIRC Mike Holt put in his own PI subsequently, which probably was important to getting the change in, as the CMPs don't know me from Adam.]

But for some reason the CMP went for a new section, 250.109 as ActionDave posted. Not sure why they did that, it seems to promote a bit of a false dichotomy. EGC-wise, there's no difference between a metal enclosure, a run of EMT, or a wire-type EGC. The definition of EGC is:

"Grounding Conductor, Equipment (EGC). (Equipment Grounding Conductor) A conductive path(s) that is part of an effective ground-fault current path and connects normally noncurrent-carrying metal parts of equipment together and to the system grounded conductor or to the grounding electrode conductor, or both. (CMP—5)"

When a metal enclosure is used to provide continuity between two runs of EMT being used as the EGC, the metal enclosure is part of the "conductive path" so it IS an EGC. Seems like therefore 250.109 belongs instead in the list in 250.118.

Cheers, Wayne

 

[ActionDave]

I first noticed the oversight and put in a PI to add metal boxes to 250.118. [IIRC Mike Holt put in his own PI subsequently, which probably was important to getting the change in, as the CMPs don't know me from Adam.]

But for some reason the CMP went for a new section, 250.109 as ActionDave posted. Not sure why they did that, it seems to promote a bit of a false dichotomy. EGC-wise, there's no difference between a metal enclosure, a run of EMT, or a wire-type EGC. The definition of EGC is:

"Grounding Conductor, Equipment (EGC). (Equipment Grounding Conductor) A conductive path(s) that is part of an effective ground-fault current path and connects normally noncurrent-carrying metal parts of equipment together and to the system grounded conductor or to the grounding electrode conductor, or both. (CMP—5)"

When a metal enclosure is used to provide continuity between two runs of EMT being used as the EGC, the metal enclosure is part of the "conductive path" so it IS an EGC. Seems like therefore 250.109 belongs instead in the list in 250.118.

Cheers, Wayne

They are a team of experts, we cannot question them.

 

[LarryFine]

I think of metallic boxes and enclosures as being grounded by conduits, not as doing grounding along with conduits, so I don't think of them as being grounding conductors.

 

[wwhitney]

I think of metallic boxes and enclosures as being grounded by conduits, not as doing grounding along with conduits, so I don't think of them as being grounding conductors.

That interpretation would work if we ensured that for any particular metallic box/enclosure, the "conductive path" (in the definition of EGC) did not depend on any other metallic box/enclosure.

But that's not how things are commonly done. If you have, say, EMT Run 1 - Box 1 - EMT Run 2 - Box 2, where the EMT is the only EGC, we rely on Box 1 to provide the conductive path between EMT Run 1 and EMT Run 2. Any fault current from a fault to Box 2 will travel through Box 1. Therefore Box 1 is part of that "conductive path" and meets the definition of EGC.

Cheers, Wayne

 

[don_resqcapt19]

There were 5 Public Inputs for the 2020 code to add metal enclosures as a list item in 250.118 and they were all rejected (resolved) at the first draft stage with the following statement.

Metal enclosures are not listed as grounding and bonding equipment. Listed metal enclosures are evaluated on how they attach to an equipment grounding conductor. The NEC presently addresses the use of metal enclosures and covers in the equipment grounding conductor path (example 250.110). There is no substantiation or field evidence provided that this has presented a safety issue

There were 3 public comments to add enclosures as equipment grounding conductors. Those Public Comments resulted in new section 250.109 with this panel statement for the second revision.

Presently metal items such as cabinets, boxes, wireways and their covers are required to be connected to equipment grounding conductors by 250.110. Stating that these metal items can be used to establish an effective ground fault current path solves the problem better than just adding those items to the list in 250.118 as suggested by the public comments.

 

[kwired]

I think of metallic boxes and enclosures as being grounded by conduits, not as doing grounding along with conduits, so I don't think of them as being grounding conductors.

Which if not allowed to be be part of the EGC path we would have needed bonding jumpers between raceways entering the box and used as EGC's for decades.

 

[electrofelon]

I first noticed the oversight and put in a PI to add metal boxes to 250.118. [IIRC Mike Holt put in his own PI subsequently, which probably was important to getting the change in, as the CMPs don't know me from Adam.]

But for some reason the CMP went for a new section, 250.109 as ActionDave posted. Not sure why they did that, it seems to promote a bit of a false dichotomy. EGC-wise, there's no difference between a metal enclosure, a run of EMT, or a wire-type EGC. The definition of EGC is:

"Grounding Conductor, Equipment (EGC). (Equipment Grounding Conductor) A conductive path(s) that is part of an effective ground-fault current path and connects normally noncurrent-carrying metal parts of equipment together and to the system grounded conductor or to the grounding electrode conductor, or both. (CMP—5)"

When a metal enclosure is used to provide continuity between two runs of EMT being used as the EGC, the metal enclosure is part of the "conductive path" so it IS an EGC. Seems like therefore 250.109 belongs instead in the list in 250.118.

Cheers, Wayne

I agree, 118 is the place for that language.

 

[kwired]

Didn't realize you could gang those MEIBB's

https://imgur.com/a/W4idbLG

I honestly wondered if any one ever landed anything on them. Other than if a service upgrade and maybe bonding conductors get moved to the new IBT, I have never seen new construction have anything landed on it. Have come back sometime later only to find the CATV, satellite etc. installers had landed their usual clamp on a meter socket or load center cabinet, even AC disconnect enclosure sometimes. I specifically remember one and probably have a picture of it somewhere, my IBT was below the main service panel, satellite dish installer put clamp on top end of panel and landed his bond wire there.

 

[LarryFine]

Therefore Box 1 is part of that "conductive path" and meets the definition of EGC.

Absolutely agree. I'm just saying that I don't, or didn't think about it as a conductor.

 

[LarryFine]

Which if not allowed to be be part of the EGC path we would have needed bonding jumpers between raceways entering the box and used as EGC's for decades.

Yes, the box is definitely part of the conductive envelope.

 

[kwired]

Yes, the box is definitely part of the conductive envelope.

NEC just never over many years specifically mentioned the box can be part of the pathway. Did say the box must be bonded though, even if only via a raceway entry, and most of us just assumed that allowed it to be part of the EGC path.

 

[wwhitney]

NEC just never over many years specifically mentioned the box can be part of the pathway.

Not only that, but because 250.118 was a definitive list of allowable EGC types, and metal enclosures were not listed there, it disallowed the box being part of the pathway. All installations prior to the 2020 NEC that relied on a box to be part of the fault current pathway were a violation of 250.118. : - ).

Cheers, Wayne

 

[Fred B]

I honestly wondered if any one ever landed anything on them. Other than if a service upgrade and maybe bonding conductors get moved to the new IBT, I have never seen new construction have anything landed on it. Have come back sometime later only to find the CATV, satellite etc. installers had landed their usual clamp on a meter socket or load center cabinet, even AC disconnect enclosure sometimes. I specifically remember one and probably have a picture of it somewhere, my IBT was below the main service panel, satellite dish installer put clamp on top end of panel and landed his bond wire there.

I've installed these and the other style before and never seen them hooked up to by any telecom. Come back later and found that the telecom connected to a close by copper water pipe that wasn't even grounded because the plumber had just used an existing section of copper that had pex on either side, or to the meter with their strap/clamp device like this:



So i wonder why even bother giving the telecom a grounding connection point.

 

[kwired]

I've installed these and the other style before and never seen them hooked up to by any telecom. Come back later and found that the telecom connected to a close by copper water pipe that wasn't even grounded because the plumber had just used an existing section of copper that had pex on either side, or to the meter with their strap/clamp device like this:

View attachment 2572813

So i wonder why even bother giving the telecom a grounding connection point.

Even before NEC required the IBT, I could have exposed bare GEC and they still would put a strap around a metal raceway or one those devices like you posted image of. Even had them loosen EMT set screw fitting and wrap their conductor around it and tighten it down again except now the set screw is no longer contacting the raceway. I think I even recall a bonding conductor wrapped around panel cover screw before