Grounding and Bonding Locknuts — Grounding and bonding locknuts
serve in a manner similar to grounding and bonding bushings except they
do not provide abrasion protection for the conductor at the end of the
conduit.
Grounding and Bonding Bushings — Bonding bushings for use with
conduit fittings, tubing (EMT) fittings, threaded rigid metal and intermediate
metal conduit, or unthreaded rigid metal and intermediate metal conduit
are provided with means (usually one or more set screws) for reliably
bonding the bushing (and the conduit on which it is attached) to the metal
equipment enclosure or box. They provide the electrical continuity
required by the NEC at service equipment and for circuits rated over 250
V. Means for connecting a grounding or bonding conductor are not provided
and if there is need for such a conductor a grounding bushing
should be used.
Grounding bushings for use with conduit fittings, tubing (EMT) fittings,
threaded rigid metal and intermediate metal conduit, or unthreaded rigid
metal and intermediate metal conduit have provision for the connection of
a bonding or grounding wire or have means for mounting a wire connector
available from the manufacturer. Such a bushing may also have means
(usually one or more set screws) for reliably bonding the bushing to the
metal equipment enclosure or box in the same manner that this is accomplished
by a bonding bushing. Grounding bushings provide the electrical
continuity required by the NEC at service equipment and for circuits rated
over 250 V. They may be used with or without a bonding or grounding
conductor as determined by the bonding or grounding function that is
intended to be accomplished.
Insulating throat liners in grounding or bonding bushings are suitable
for temperatures of 150°C if they are black or brown in color. Unless otherwise
marked, insulating throat liners of any other color are suitable for
temperatures of 90°C.
