Chapter 4 Wiring Systems
83
Copyright Goodheart-Willcox Co., Inc.
Raceways
Raceways are protective coverings installed
on site and used to contain wires. Raceway mate-
rials are selected depending on the intended
application. Wire size and ampacity, environment,
installation conditions (new or remodel), building
codes, and cost are all factors that will determine
the selection of a raceway. Raceways consist of
conduit, boxes, and fi ttings. Conduit is the tubing
connecting the boxes together. The wires are
pulled from box to box through the conduit. Boxes
can be used for either junctions to connect the
wires or mounting devices such as lamp fi xtures,
switches, and outlet receptacles. Fittings are used
to connect pieces of conduit together, and connec-
tors are used to connect the conduit to the boxes.
Electrical Metallic Tubing
Electrical metallic tubing (EMT) is called
thin-wall conduit. EMT is not designed to be
threaded; therefore, it is connected length-
to-length or to electrical boxes with suitable
compression or setscrew fi ttings. When installed
correctly, EMT is used as an effective equipment
grounding conductor. See Figure 4-14.
Electrical Metallic Tubing: Type EMT — Article 358
Locations Allowed
Dry
Wet
Sizes
1/2″
through
4″
Maximum Mounting Distance
3′
10′
Setscrew fitting
(coupling)
Compression fitting
(coupling)
Connector Coupling
Locknut for the
connector
Figure 4-14. These are various types of EMT fi ttings.