Enclosures for the GEC

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finhead

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I have seen several illustrations in various books of bonding jumpers installed on each end of a ferrous metal enclosure for a grounding electrode conductor. However, Section 250.64(E) states that such bonding is required only where the enclosures are not physically continuous. If, for example, the GEC enclosure is EMT and is connected to the service panel with an EMT connector and locknut, is the bonding jumper still required at the panel?

Thanks,
Brian Dolan
 
I say that they're not required but others here feel that they are. Mike Holt seems to think that they are required too.
 
"Electrically continuous" is pretty vague.... Many inspectors here will accept a grounging/bonding type lock-nut. Having been doing some light reading of the NEC Style Manual lately - they have several lists of "Vauge Terms" - many of which can be found throughout the code....
 
Mr Baker agrees with Mr. holt ,...both ends

http://www.imsasafety.org/journal/ma06/4.pdf


....if not bonded at each end to the grounding electrode conductor, acts as an impedance choke, and can restricts up to 97% of the fault current from lightning induced current on the grounding electrode conductor. Raceways and any intervening metallic junction boxes must be bonded with a grounding bushing, not a grounding locknut.
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Tom Bakers opinion aside, if you enter a service panel with the GEC in a metallic raceway the raceway is connected to the metal can which is connected to the neutral which is connected to the GEC. So if you read the wording of the requirement I don't see where an additional redundant connection from the raceway is needed. Maybe someone can enlighten me.:cool:

250.64(E) Enclosures for Grounding Electrode Conductors. Ferrous metal enclosures for grounding electrode conductors shall be electrically continuous from the point of attachment to cabinets or equipment to the grounding electrode and shall be securely fastened to the ground clamp or fitting. Nonferrous metal enclosures shall not be required to be electrically continuous. Ferrous metal enclosures that are not physically continuous from cabinets or equipment to the grounding electrode shall be made electrically continuous by bonding each end of the raceway or enclosure to the grounding electrode conductor. Bonding shall apply at each end and to all intervening ferrous raceways, boxes, and enclosures between the cabinets or equipment and the grounding electrode. The bonding jumper for a grounding electrode conductor raceway or cable armor shall be the same size as, or larger than, the enclosed grounding electrode conductor. Where a raceway is used as protection for a grounding electrode conductor, the installation shall comply with the requirements of the appropriate raceway article.
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e57 said:
"Electrically continuous" is pretty vague.... Many inspectors here will accept a grounging/bonding type lock-nut. Having been doing some light reading of the NEC Style Manual lately - they have several lists of "Vauge Terms" - many of which can be found throughout the code....
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The NEC does not allow a grounding locknut. Only a bonding bushing.
 
Thanks for the input. I have to agree with Infinity. The NEC specifically prohibits standard locknuts and bushings for bonding of service raceways. They could have included enclosures for grounding electrode conductors in these heightened bonding requirements, but did not.
 
finhead said:
Thanks for the input. I have to agree with Infinity. The NEC specifically prohibits standard locknuts and bushings for bonding of service raceways. They could have included enclosures for grounding electrode conductors in these heightened bonding requirements, but did not.
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Enclosures and Raceways are two different items.
 
If the electrode is a water pipe and there is a two bolt clamp with bonding hub, an EMT connector screwed into the hub and the EMT runs back to the service panel, then all that is needed at the service panel is an EMT connector.

Because the raceway is continuous from the cabinet to the electrode.
 
sandsnow said:
If the electrode is a water pipe and there is a two bolt clamp with bonding hub, an EMT connector screwed into the hub and the EMT runs back to the service panel, then all that is needed at the service panel is an EMT connector.

Because the raceway is continuous from the cabinet to the electrode.
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Larry, 250.64(E) says both ends.
 
benaround said:
Larry, 250.64(E) says both ends.
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ferrous metal enclosures that are not physically continuous from cabinets or equipment to the grounding electrode shall be made continuous by bonding each end of the raceway or enclosure to the grounding electrode conductor.

I can't do all that fancy highlighted underline italics stuff. Anyway, bond both ends only if raceway is not continuos
 
sandsnow said:
ferrous metal enclosures that are not physically continuous from cabinets or equipment to the grounding electrode shall be made continuous by bonding each end of the raceway or enclosure to the grounding electrode conductor.

I can't do all that fancy highlighted underline italics stuff. Anyway, bond both ends only if raceway is not continuos
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Agian, enclosures and raceways are two different items. 250.92(A)(3) is

another section that spells out both ends of a raceway. Do you agree?
 
benaround said:
Agian, enclosures and raceways are two different items. 250.92(A)(3) is

another section that spells out both ends of a raceway. Do you agree?
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I think we're talking apples and oranges here. 250.92(A)(3) is just requiring the raceway to be bonded to the cabinet. It does not require the raceway to be bonded to the conductor.

In 250.64(E) it is my opinion that enclosure is synonymous with raceway in this subsection. Used here the word enclosure is an umbrella term that covers boxes and raceways and other enclosures.
 
sandsnow said:
I think we're talking apples and oranges here. 250.92(A)(3) is just requiring the raceway to be bonded to the cabinet. It does not require the raceway to be bonded to the conductor.

In 250.64(E) it is my opinion that enclosure is synonymous with raceway in this subsection. Used here the word enclosure is an umbrella term that covers boxes and raceways and other enclosures.
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Ok, this will be my last attempt. I'm using the NECH, after 250.92(A)(3) the
commentary reads

Section 250.92(A)(3) is intended to clarify that where metal raceways, boxes, or enclosures contain a GEC, both ends of the raceway, box, or enclosure must be bonded to the GEC, as illustrated in Exhibit 250.32.
Bonding the raceway to the GEC reduces the impedance and minimizes
the potential difference between the electrical equipment and ground.

After 250.64(E) it says about the same thing plus; shows the bonding of a
ferrous metal raceway to a GEC at both ends to ensure the raceway and
conductor are in parallel.

This is all i've got.
 
sandsnow said:
I think we're talking apples and oranges here. 250.92(A)(3) is just requiring the raceway to be bonded to the cabinet. It does not require the raceway to be bonded to the conductor.
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I also agree with that.
 
I spoke to Phil Simmons, past chairman and current member of CMP5, about this at the last code class that I attended. His position is that the ferrous raceway must be bonded directly to the conductor at each end.
I don't read the words that way, but am just passing on a comment. His opinion as an individual is no more valid than any of ours, but I expect that if this issue were to be submitted for a FI, he would be able to get the required number of votes to support his opinion.
 
Ok, I know this won't make any sense in NEC terms.

BUT>>>

If the Code wants the conductor bonded at both ends to the raceway, why doesn't it just say that and not go through so much verbage.

Drives me crazy. And after all this time I can still find a section I though I knew but really didn't.
 
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