When are bonding bushings needed?

[royboy75]

Hello all,

Could somebody give me some clarification on the use of bonding bushings. I have had a inspector say that they only have to be used when the voltage is over 600v and eccentric/concentric knockouts are present. He said that both things had to be present to have to use them. Other inspectors have made me put them on one side of emt on 240v circuits no matter what the knockout is. Then some have made me put them on both ends of emt. If there is a code reference on this, please share. One inspector said they had to be on metal flex on both ends, no matter what. Please help!

Thanks

 

[Dennis Alwon]

Bonding bushings are used on metal raceways when the raceways have service conductors in them. Bonding bushings are also used when the grounding electrode conductor is in a metal raceway- both ends need to be bonded and one end often has a bonding bushing.

With voltage over 250v to ground article 250.97 speaks.

250.97 Bonding for Over 250 Volts. For circuits of over
250 volts to ground, the electrical continuity of metal raceways
and cables with metal sheaths that contain any conductor other
than service conductors shall be ensured by one or more of the
methods specified for services in 250.92(B), except for (B)(1).
Exception: Where oversized, concentric, or eccentric knockouts are not
encountered, or where a box or enclosure with concentric or eccentric
knockouts is listed to provide a reliable bonding connection, the following
methods shall be permitted:
(1) Threadless couplings and connectors for cables with metal
sheaths
(2) Two locknuts, on rigid metal conduit or intermediate metal
conduit, one inside and one outside of boxes and cabinets
(3) Fittings with shoulders that seat firmly against the box or cabinet,
such as electrical metallic tubing connectors, flexible metal
conduit connectors, and cable connectors, with one locknut on
the inside of boxes and cabinets
(4) Listed fittings