Chapter 5 Wiring Methods 65
Copyright Goodheart-Willcox Co., Inc.
Figure 5-12. This table compares several sizes of rigid metal conduit and EMT. Cross sections of nominal 3/4″ raceway are shown.
The EMT is lighter and more affordable, while the rigid metal conduit is more sturdy and durable.
Conduit Properties
Rigid Steel Conduit EMT
Trade Size OD ID Wall Weight OD ID Wall Weight
Thickness (lb/1000′) Thickness (lb/1000′)
1/2 0.840 0.622 0.109 820 0.706 0.622 0.042 295
3/4 1.050 0.824 0.113 1120 0.922 0.824 0.049 445
1 1.315 1.049 0.133 1600 1.163 1.049 0.057 650
2 2.375 2.067 0.154 3500 2.197 2.067 0.065 1410
3 3.500 3.068 0.216 7120 3.500 3.356 0.072 2700
4 4.500 4.026 0.237 10,300 4.500 4.334 0.083 4000
3/4″ Rigid
Metal Conduit
3/4″ EMT
Figure 5-13. EMT couplings and connectors. (RACO, Inc.)
EMT Fittings
Rigid to EMT
Set Screw Coupling
2 1/2″ – 4″ 1/2″ – 1″
Rigid to EMT
Threaded/Compression
Coupling
1 1/4″ – 2″
Set Screw Couplings
2 1/2″ – 4″ 1/2″ – 1″
Compression
Connector
Compression
Coupling
Indenter
Coupling
1 1/4″ – 2″
Set Screw Connectors
conduit, although their outer diameters are about the
same. See Figure 5-12. IMC is also thicker than EMT.
This advantage of lighter weight is offset by the loss
in ability to withstand physical damage. EMT does not
enjoy as wide a variety of permitted usage as does rigid
metal or intermediate metal conduit. Still, EMT may be
used in most locations.
EMT is not threaded. Its couplings and connectors
can be set screw, compression, or indenter types. See
Figure 5-13. It is supported at intervals of no more than