Chapter 5 Wiring Methods 71
Copyright Goodheart-Willcox Co., Inc.
3. Regarding cable trays, what is allowed in industrial
applications that is not allowed in commercial
applications?
4. Describe surface raceway.
5. Which Code article contains the requirements for
underground feeder cable?
6. What is normally the maximum number of conduc-
tors that can be placed in a single wireway?
7. Can the conductors for a single circuit be located in
different conduit runs?
8. Which conduit has thicker walls: IMC or EMT?
9. Compare the support requirements of ENT with
other wiring methods. What is the reason for the
difference?
10. Under what conditions can conductors with different
voltage ratings be located within the same conduit?
11. What are the four main types of cable?
12. What are the requirements for protecting conduit
running through wall studs?
13. What percentage of wireway area can be filled by
conductor splices?
14. What type of cable is called Romex?
15. What is the minimum burial depth of rigid metal
conduit below a residential driveway?
16. In what situations is service-entrance cable used?
17. Is direct burial of type USE cable allowed?
18. When underground wiring is used, how far above
ground level must the raceway extend at the point
where the conductors exit the ground?
19. What methods can be used to support vertical
conductors?
20. Which type of cable does FMC resemble?
21. What is the maximum total cross-sectional area of
conductors that can be placed in a 4″ × 4″ rectangular
wireway?
22. A cable splice that will occupy 8.8 in2 is proposed to
be located in a 3″ × 4″ wireway. Will this splice
satisfy wireway space limitation requirements?
USING THE NEC
Refer to the National Electrical Code to answer the
following questions.
1. Section 392.10(D) defines two areas in which
nonmetallic cable trays can be used. What are these
two areas?
2. Table 300.5 lists minimum burial depths. In general,
which needs to be buried deeper, IMC or PVC
conduit?
3. Section 300.4 defines requirements for protecting
wiring methods. What must be installed to protect
electrical nonmetallic tubing running through metal
framing members?
4. An inspector cited a violation for supporting one
conduit with a hanger attached to another conduit.
Which Code section does this practice violate?
5. Can an IMC wiring system be installed in an air
duct containing flammable vapors?
6. Is a 2″ × 4″ rectangular wireway large enough to
safely contain six 3/0 AWG XHHW, six 12 AWG
XHHW, and four 14 AWG XHHW conductors?
7. Metal-clad cable is permitted for use in wet loca-
tions if any one of three conditions are met. What
are these conditions?
8. A wireway containing six 2/0 AWG THHN and two
14 AWG THHN conductors is needed for a project.
The wireway must be 2″ wide. What depth of
wireway should be ordered (assuming the depth
must be ordered in 1″ increments)?
9. What is the maximum allowable interval between
supports for strut-type channel raceway?
10. The length of rigid nonmetallic conduit changes
due to thermal contraction and expansion. Expansion
fittings are used to compensate for these changes.
What is the maximum allowable length change in a
straight run of conduit without expansion fittings?
11. When lighting busways and trolley busways are not
provided with covers, what is the minimum height
above the floor at which they can be installed?
12. Of metal wireways and nonmetallic wireways,
which can be used where subject to corrosive
vapors?