Requirement for Bonding Bushings

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Can anyone point me to NEC reference requiring BLG (Bonding Lug Grounding) bushings?
I see 300.4F requiring a bushing on # 4 AWG and larger conductors - & See 344.46 requiring a bushing to protect wire from abrasion when using rigid conduit - I could surmise that when using 344.60 (Rigid as ground) that the bonding lug bushing may be used to extend grounding conductor to ground bar, however as the ground bar is normally mounted to the can and rigid is normally connected through single KO not concentrict and double locknutted to the can, I beginning to wonder where & why the grounding bushing becomes a requirement, if for bonding of conduit I would think that in rigid application that is overkill / EMT perhaps - Any code clarifications on this would be greatly appreciated.

Thanks
Steve
 

infinity

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I beginning to wonder where & why the grounding bushing becomes a requirement, if for bonding of conduit I would think that in rigid application that is overkill / EMT perhaps - Any code clarifications on this would be greatly appreciated.

Thanks
Steve

IMO it not a requirement. The conduit is bonded to the can, the can to the neutral and the GEC to the neutral. Sounds like they're already connected together.
 

augie47

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I think the important, often overlooked, words are the last ones in the complete 250.92(B) section: "Standard locknuts or bushings shall not be the sole means for the bonding required by this section"

I don't know how often I hear "but there were no concentric knockouts"
but the last sentence state "by this section"
 

cadpoint

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250.92 - Services
250.97 - Bonding for over 250 volts
250.100 - Bonding in Hazardous Classified Locations

Just a Few:smile:

I had a inspector walk in and ask the question, "Why, did you bond all the branch circuits for the downline panels?", now this is out of a MDP. "Ah, cause its required...", I said...

Did I pass ? 250.92, Frankly I was thinking of 250.80 and 250.86 as well.
Besides six of seven where MC rate branch service conductors, which is a whole nother code...

He also asked if I pulled 2 inch flex and feed it through, I had to show him the Bone on the Reel ...
 
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If I understand you correctly, the last sentence...
"Standard lock nuts or bushings shall not be the sole means for the bonding required by this section."

They mean these:

6105324.jpg


6320634.jpg
 

russ

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Burbank IL
If I understand you correctly, the last sentence...
"Standard lock nuts or bushings shall not be the sole means for the bonding required by this section."

They mean these:

6105324.jpg


6320634.jpg

Yes, although the bushing their referring to may be the old metal ones. Some times I,d fined those metal bushings without a locknut on the inside of a box.
 

infinity

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That was, and still is legal.


And that was a standard installation practice for decades in apartment building piping. It saves a locknut at every termination and also takes up the least amount of space in the box.
 
Thanks for your input

Thanks for your input

IMHO 250-97 Lists exceptions in item (2) - Two locknuts on rigid conduit one on either side of the enclosure in either a non-concentric opening or a listed concentric opening and goes further with item (3) regarding fittings such as EMT or FMC. - The requirment is to bond double locknut either side of enclosure on rigid has been an acceptted standard for years -
I suppose bonding type LN could be used - but this particular reference is not spelling that out. My dig is not against bonding or good pratices, it is more so against cheap bonding bushings with little substance for throat during wiring pulling - Personally I prefer OZ Gedney "A" series bushings they are rated for 150 C and have never failed me in a wire pull.
If Have to...The OZ BLG grounding are the best I've ever seen - but who can afford to price those into a job and get the work?

Thank all of you for your input.

Steve
 

infinity

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IMHO 250-97 Lists exceptions in item (2) - Two locknuts on rigid conduit one on either side of the enclosure in either a non-concentric opening or a listed concentric opening and goes further with item (3) regarding fittings such as EMT or FMC. - The requirment is to bond double locknut either side of enclosure on rigid has been an acceptted standard for years -


I agree that over 250 volts, RMC would require two locknuts. Under 250 volts a metallic bushing on the inside and a locknut on the outside would suffice.
 

augie47

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I agree that over 250 volts, RMC would require two locknuts. Under 250 volts a metallic bushing on the inside and a locknut on the outside would suffice.

That statement, as written, would be excluding service conduits, correct ?
For services of any voltage, 250.92 would still require something other than "standard locknuts & bushings" would it not.
 

infinity

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That statement, as written, would be excluding service conduits, correct ?
For services of any voltage, 250.92 would still require something other than "standard locknuts & bushings" would it not.


Yes, services would be a different set of rules. Even two locknuts on RMC would not satisfy the requirements for bonding service raceways. My original post was about apartment deck conduits which is what I was referencing.
 
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