Locknuts With grounding/Bonding bushings

[settwilliams]

Hello all I’m new to the forum hopefully someone can help a poor apprentice out.

Are locknuts required to be used with grounding bonding bushings? I’m asking because I made a boo boo and I left the locknut off thinking there wasn’t enough thread. Was that a huge mistake on my part ?

 

[LarryFine]

Welcome to the forum.

If I'm not mistaken, a metallic bonding bushing may be used opposite a single lock-nut as long as it's tight to the enclosure.

 

[infinity]

What kind of raceway, RMC?

 

[LarryFine]

What kind of raceway, RMC?

I obviously presumed as much.

 

[Greentagger]

Hello all I’m new to the forum hopefully someone can help a poor apprentice out.

Are locknuts required to be used with grounding bonding bushings? I’m asking because I made a boo boo and I left the locknut off thinking there wasn’t enough thread. Was that a huge mistake on my part ?

I would presume the lock nut is required to mechanically secure the raceway or fitting, and that the bonding bushing is used for the required bonding. I would not think the listed purpose for the grounding bushing is to secure the raceway or fitting.

 

[tortuga]

Welcome to the forum.

If I'm not mistaken, a metallic bonding bushing may be used opposite a single lock-nut as long as it's tight to the enclosure.

Agreed 300.4(G) only prohibits bushings made wholly of insulating material.
They used to sell plain metal bushings that were not bonding bushings to use in lieu of a locknut, they still might.

 

[electrofelon]

I

Agreed 300.4(G) only prohibits bushings made wholly of insulating material.
They used to sell plain metal bushings that were not bonding bushings to use in lieu of a locknut, they still might.

I Also agree, and it doesn't appear to matter whether you have a fitting like an EMT connector or rigid conduit. You may have to remove any paint on the surfaces.

 

[letgomywago]

Agreed 300.4(G) only prohibits bushings made wholly of insulating material.
They used to sell plain metal bushings that were not bonding bushings to use in lieu of a locknut, they still might.

I've taken those out but never seen them sold

 

[infinity]

Agreed 300.4(G) only prohibits bushings made wholly of insulating material.
They used to sell plain metal bushings that were not bonding bushings to use in lieu of a locknut, they still might.

Yes a common installation with mud boxes within concrete. Enter RMC into the box with a metal bushing on the inside and a single locknut on the outside.

 

[Eddie702]

If I am not mistaken it used to be for 250v-ground and under a metal bushing and a locknut on the outside was perfectly legal for IMC or RMC and for over 250-ground two locknust and a bushing (metal or plastic) is fine.

 

[augie47]

One of the large industrial sites where we worked had original wiring dating back to the 50s and all their conduit runs were locknut outside of the box, metal bushing inside.
(also no wire type EGC...when there was a phase to ground short it looked like someone opened a case of sparklers...sparks rained from about 1/4 of the exposed ceiling boxes where the bushings were not tight)