grounding termination poiunts for steel conduits anmd fittings

[howardrichman]

I'm installing a sub panel fed from a main panel that's fed from a main disconnect. When leaving the 1st distribution panel, I'm installing EMT to feed a subpanel. Do I need to install ground bushings for concentric and ground locknuts for non-concentric knockouts for all fittings and HW pipe entering a j-box or panel to secure a ground ? I could just install a ground conductor, but should not be necessary. In that case how can just a locknut/bushing alone be sufficient to carry a ground for general wiring in steel conduit between j-boxes and other terminating points?

HR...

 

[kwired]

I'm installing a sub panel fed from a main panel that's fed from a main disconnect. When leaving the 1st distribution panel, I'm installing EMT to feed a subpanel. Do I need to install ground bushings for concentric and ground locknuts for non-concentric knockouts for all fittings and HW pipe entering a j-box or panel to secure a ground ? I could just install a ground conductor, but should not be necessary.

HR...

under 250 volts to ground no, over 250 volts to ground, maybe - depends on any rating of the concentric KO's

Non eccentric/concentric KO is fine with standard locknuts regardless of voltage. But service raceways need bonded by more then just a standard locknut.

 

[howardrichman]

under 250 volts to ground no, over 250 volts to ground, maybe - depends on any rating of the concentric KO's

Non eccentric/concentric KO is fine with standard locknuts regardless of voltage. But service raceways need bonded by more then just a standard locknut.

Thanks for reply;
I'll probably use grounding locknuts to confirm a ground between points.
HR...