service conduit grounding bushings

[chrisd]

Are they required at both ends of a service conduit that has couplings, or other fittings in it?

[electric-ed]

They are only required where the metal service raceway enters a metal box, on the line side of the disconnecting means overcurrent devices.

It is intended to supplement the connection between the conduit and box where concentric knockouts are commonly used in a location where the only overcurrent device that can clear a ground fault is the transformer primary fuse.

Ed