94
Section 2 Installation
RMC nipples
Preformed bends
Coupling
Conduit
bodies
Bushing
Locknuts
Figure 4-26. Rigid metallic conduit is threaded so that it can be attached to fi ttings and couplings.
Rigid Metal Conduit
Rigid metal conduit (RMC) is galvanized
and somewhat similar to water pipe. It is used
for both indoor and outdoor applications.
Inside and out, the conduit is smooth and can
be cut, threaded, reamed, and bent as neces-
sary for proper installation. To cut RMC with
a pipe cutter, follow the cutting procedure
demostrated in the previous EMT section RMC
must be fi rmly connected to items such as elec-
trical outlet boxes, and panels with a threaded
locknut and bushing. This solid connection is
necessary because the conduit itself serves as
the equipment grounding conductor. Thus, a
separate equipment grounding conductor is
not required when using RMC. Fittings should
maintain a continuous ground throughout the
system. See Figure 4-26.
Rigid Metal Conduit: Type RMC — Article 344
Locations Allowed
Dry
Wet
Corrosive
Sizes
1/2″
through
6″
Maximum Mounting Distance
3′
10′
Code Alert
Section 344.46
Where a conduit enters a box, fi tting, or
other enclosure, a bushing shall be provided
to protect the wire from abrasion unless the
design of the box, fi tting, or enclosure is such
as to afford equivalent protection.
rigid metal conduit (RMC): This is the original con-
duit, used before thin-wall and IMC. RMC, also
called heavy-wall conduit, has thick walls and provides
the greatest protection for the wires inside. Small sizes
can be bent by hand with diffi culty; larger sizes must
be machine-bent.