Bonding bushing

[joeyww12000]

Are bonding bushings required when running a GEC to building steel if the conduit is EMT? Coming out of MDP ground bar to building steel. I know the answer but once again foreman is non compliant.

 

[roger]

Bond bushings are not required, but both ends of the conduit must be bonded to the conductor by some means. At the panel it can simply be a connector and locknut, the other end could be a bond bushing or other means.

Roger

 

[dnem]

Bond bushings are not required, but both ends of the conduit must be bonded to the conductor by some means. At the panel it can simply be a connector and locknut, the other end could be a bond bushing or other means.

Roger: "At the panel it can simply be a connector and locknut"
250.92(B): "Standard locknuts or bushings shall not be the sole means for the bonding required by this section."

 

[tryinghard]

Are bonding bushings required when running a GEC to building steel if the conduit is EMT? Coming out of MDP ground bar to building steel. I know the answer but once again foreman is non compliant.

I say yes, see 250.64(E) "Ferrous metal...shall be made electrically continuous by bonding eacn end of the raceway to the gounding electrode conductor." Use PVC or open conductor to go around this.

 

[roger]

Roger: "At the panel it can simply be a connector and locknut"
250.92(B): "Standard locknuts or bushings shall not be the sole means for the bonding required by this section."

You'd be correct if this raceway was for the service conductors, but we are talking about the GEC and the way 250.92 (B) is worded the GEC is not included.

(B) Method of Bonding at the Service Electrical continuity at service equipment, service raceways, and service conductor enclosures shall be ensured by one of the following methods:

Service Conductors. The conductors from the service point to the service disconnecting means.

Service Point. The point of connection between the facilities of the serving utility and the premises wiring.

BTW, I can see where you are coming from but, if we use the reasoning that since this raceway is connected to the service equipment and must use more than a standard locknut for bonding, then we would have to use the same reasoning for any branch circuit conduit that enters a Main Panel as well.

Roger

 

[infinity]

I agree with Roger and have taken issue with Mike's graphic in the past because IMO it's incorrect.

 

[dnem]

BTW, I can see where you are coming from but, if we use the reasoning that since this raceway is connected to the service equipment and must use more than a standard locknut for bonding, then we would have to use the same reasoning for any branch circuit conduit that enters a Main Panel as well.

Roger

I wasn't using the reasoning that 250.92 applies to the metal raceway for the electrode conductor because it is connected to the service equipment. . I was classifying the metal raceway for the electrode conductor, it itself as a service raceway [250.92(A)(1)], but reading this section repeatedly I don't see clear support for this classifying.

#1] What does the wording in the NEC actually say ? . Is it clear ? . If yes, then skip to #4.
#2] Is there other language within the NEC that might not directly apply but can help understand a word or phrase ? . If yes, then skip to #4.
#3] Is there info in an ROP, NEC Handbook, or UL Whitebook that helps clear up the question ?
#4] Take the best answer you have at this point and apply common sense to the specific installation that you're looking at.
#5] Is it still unclear which of several options are required ? . Then accept any of those possible options that the contractor chooses.

#1] What does the wording in the NEC actually say ? . Is it clear ? . If yes, then skip to #4.
No, 250.92(A)(1) by itself is not clear to me if an electrode conduit is or is not a service conduit.

#2] Is there other language within the NEC that might not directly apply but can help understand a word or phrase ? . If yes, then skip to #4.
Yes, it appears that a conduit that encloses a grounding electrode conductor is called a “grounding electrode conductor raceway” [250.64(E)] and these raceways are found in places other than services such as a SDS [250.30].

#4] Take the best answer you have at this point and apply common sense to the specific installation that you're looking at.
I see that the word “electrode” doesn’t appear anywhere within 250.92 and without that language I don’t see that “service raceway” can also be applied to an electrode conductor conduit.

 

[dnem]

I agree with Roger and have taken issue with Mike's graphic in the past because IMO it's incorrect.

But we've been talking about 250.92(B): "Standard locknuts or bushings shall not be the sole means for the bonding required by this section."

Mike Holts graphic depicts 250.64(E). . How does the Mike Holt graphic misrepresent 250.64(E) ?

 

[infinity]

But we've been talking about 250.92(B): "Standard locknuts or bushings shall not be the sole means for the bonding required by this section."

Mike Holts graphic depicts 250.64(E). . How does the Mike Holt graphic misrepresent 250.64(E) ?

I am in agreement with Roger's statement:

Bond bushings are not required, but both ends of the conduit must be bonded to the conductor by some means. At the panel it can simply be a connector and locknut, the other end could be a bond bushing or other means.

If you look at Mike's graphic it clearly shows the panel with a bonding bushing and jumper from the conduit to the neutral. This is not required since the neutral is bonded to the can and so is the conduit. The bonding jumper in this case is redundant and not required.

 

[elohr46]

I am in agreement with Roger's statement:




If you look at Mike's graphic it clearly shows the panel with a bonding bushing and jumper from the conduit to the neutral. This is not required since the neutral is bonded to the can and so is the conduit. The bonding jumper in this case is redundant and not required.

I agree with you to a point. However, the first sentence in that article (2005 codebook) says the "ferrous metal enclosure shall be securely fastened to the ground clamp or fitting". I have never seen this done to a ground rod, water pipe electrode, yes. So, is this graphic correct because the conduit is not "securely fastened" to the ground rod? I am just thinking out loud.

 

[infinity]

However, the first sentence in that article (2005 codebook) says the "ferrous metal enclosure shall be securely fastened to the ground clamp or fitting".

IMO the bonding bushing qualifies as a fitting so you have the option of using either the BB or the ground clamp.

 

[wawireguy]

Required.. yes.. will anyone get hurt if they aren't there. No.

 

[roger]

Required.. yes..

Yes for bond bushings or yes it must be bonded at each end?

will anyone get hurt if they aren't there. No.

How do you know what will happen during a HV surge or a Lightning event with or without this bonding?

Roger