LFMC conduit with one locknut on inside of panelboard

[Dale001289]

I have a 120/208V 3ph 4wire LV power panel board with a 2" incoming, LFMC conduit, connected to the panelboard with a 90 degree elbow. The conduit fitting has one locknut on the inside of the panelboard along with a plastic bushing (no bonding stud). The outside of the 90 degree conduit fitting where it attaches to the panelboard, has no locknut. The circuit is 208V, three phase plus neutral from a nearby dry type transformer. Is the conduit adequately bonded per NEC or does it need a grounding bushing on the inside?

 

[infinity]

A single locknut is sufficient. A standard locknut on the outside would probably defeat the wet location rating of the connector.

 

[Dale001289]

What if the circuit was 277V to ground; would 250.97, exception 2 apply?

 

[infinity]

What if the circuit was 277V to ground; would 250.97, exception 2 apply?

Yes Exception(3) would apply to the LFMC connector if there are no concentric or eccentric KO's.

 

[roger]

What if the circuit was 277V to ground; would 250.97, exception 2 apply?

I would say 3 & 4 probably has it covered

 

[Dale001289]

Yes Exception(3) would apply to the LFMC connector if there are no concentric or eccentric KO's.

thanks infinity and Roger