Solid Copper, Armored GEC

[c_picard]

Do you feel it is necessary to install a bonding bushing on the connector at the main panel? Or is using the correct listed connector at each end sufficient to avoid the "choke effect" with the GEC in a metallic armor sheath?

 

[texie]

Do you feel it is necessary to install a bonding bushing on the connector at the main panel? Or is using the correct listed connector at each end sufficient to avoid the "choke effect" with the GEC in a metallic armor sheath?

If the armor is ferrous metal it would have to have additional bonding per 250.62(E), which directs you to 250.92(B). If the armor is aluminum no additional bonding would be required.

 

[rojay]

Do you feel it is necessary to install a bonding bushing on the connector at the main panel? Or is using the correct listed connector at each end sufficient to avoid the "choke effect" with the GEC in a metallic armor sheath?

I would say no. My understanding of 250.92E indicates that the enclosure (armor in this case) for the GEC has to be electrically continuous from the point of attachment to cabinets or equipment to the grounding electrode. If it is properly connected to the grounding electrode, isnt it already continuous via the listed connector at the panel without an additional bonding bushing?

 

[rojay]

My understanding of 250.92E

My bad- thats 250.64E

 

[texie]

If the armor is ferrous metal it would have to have additional bonding per 250.62(E), which directs you to 250.92(B). If the armor is aluminum no additional bonding would be required.

Oops, I just noticed a critical typo- that should be 250.64(E).

 

[texie]

I would say no. My understanding of 250.92E indicates that the enclosure (armor in this case) for the GEC has to be electrically continuous from the point of attachment to cabinets or equipment to the grounding electrode. If it is properly connected to the grounding electrode, isnt it already continuous via the listed connector at the panel without an additional bonding bushing?

Just because you use a listed connector, that does not imply that it meets the requirements of 250.92(B). If you are using the 2011 NEC, the language in 250.64(E) is plain that you must refer to 250.92(B)(2-4). Interestingly, the 2008 language is not this clear but I believe that this has always been the intent. Even the 2008 Handbook makes this same conclusion.

 

[rojay]

Just because you use a listed connector, that does not imply that it meets the requirements of 250.92(B). If you are using the 2011 NEC, the language in 250.64(E) is plain that you must refer to 250.92(B)(2-4). Interestingly, the 2008 language is not this clear but I believe that this has always been the intent. Even the 2008 Handbook makes this same conclusion.

I must concur It 's funny that you mention the handbook. Looking at the 2011 handbook portrays a similar scenario in exhibit 250.28 with bonding jumper /bushing.