Deck 4: Conductor Sizes and Types, Wiring Methods, Wire Connections, Voltage Drop, Neutral Conductor Sizing for Services

Question 1

The NEC in Table 210.24 shows that the minimum conductor size for branchcircuit wiring is ____.

A) 20 AWG
B) 18 AWG
C) 16 AWG
D) 14 AWG

Answer 1

D

Question 2

Under certain circumstances, the grounded (neutral) conductors of a residential service ____ permitted to be sized smaller than the phase conductors.

A) are
B) are not

Answer 2

A

Question 3

Low voltage (high voltage drop) in a home can be caused by ____.

A) a conductor that is too small for the load
B) a circuit that is too long
C) poor connections at the terminals
D) all of these

Answer 3

D

Question 4

Branch circuit conductors shall have an ampacity ____ the maximum to be served.

A) one-fourth
B) one-half
C) not less than
D) 125% greater than

Question 5

Older electrical books and plans sometimes use the term "MCM," which means the same thing as ____.

A) metric
B) kcmil
C) A.I.C.
D) GFCI

Question 6

The ampacity of Type NM cable shall be in accordance with ____ conductor temperature rating.

A) 60°C (140°F)
B) 75°C (167°F)
C) 90°C (194°F)
D) None of the above

Question 7

The total rating of utilization equipment fastened in place, other than luminaires (lighting fixtures), shall not exceed ____ percent of the branch-circuit ampere rating, where lighting units, cord and plug connected utilization equipment not fastened in place, or both, are also supplied.

A) 30
B) 50
C) 75
D) 90

Question 8

A dual-rated conductor marked THHN/THWN is rated ____ when used in dry locations.

A) 90°C (194°F)
B) 75°C (167°F)
C) 60°C (140°F)
D) 30°C (86°F)

Question 9

Conductor sizes up through 4/0 AWG are expressed in American Wire Gauge (AWG). Conductor sizes larger than 4/0 AWG are expressed in ____.

A) metric units
B) kcmil
C) diameter
D) radians

Question 10

For a given conductor size, which material has the greatest ampacity?

A) copper
B) copper-clad aluminum
C) aluminum
D) both b and c

Question 11

Liquidtight flexible nonmetallic conduit is subject to which of the following limitations?

A) cannot be used in direct sunlight, unless marked for this application
B) can become brittle in extremely cold temperatures
C) both of these

Question 12

Type ____ is the most common building wire used today.

A) THW
B) THHN/THWN
C) RUW
D) RUH

Question 13

In which location(s) is Type NM cable NOT allowed to be run?

A) Concealed in dry locations
B) Damp and moist locations
C) Exterior masonry block or tile walls
D) Both b and c

Question 14

Type AC cable is manufactured with ____ phase conductors.

A) two
B) three
C) four
D) all of these

Question 15

The National Electrical Code does NOT allow rigid PVC conduit to ____.

A) be installed concealed
B) support lighting fixtures
C) support conduit bodies
D) be used in damp and wet locations

Question 16

Article 210 applies to branch circuits, but branch-circuit calculations are covered in ____.

A) Article 220
B) Article 230
C) Article 240
D) Article 250

Question 17

Connectors marked ____ are suitable for use with aluminum, copper, or copper-clad conductors.

A) CO-ALR
B) AL/CU
C) UL 9
D) both a and b

Question 18

When a 4 ft. piece of nonmetallic-sheathed cable is used as a fixture whip above an accessible ceiling, it ____.

A) is not required to be secured
B) may be up to six feet in length
C) is required to be plenum-rated
D) is subject to all of the above requirements

Question 19

The NEC requires that conductors 8 AWG and larger must be ____ when installed in a raceway.

A) grounded
B) bonded
C) stranded
D) none of these

Question 20

The rating of a branch circuit is determined by its ____.

A) overcurrent protective device (fuse or circuit-breaker)
B) wire size
C) demand factor
D) connected load

Question 21

Explain what flexible metallic and nonmetallic conduits are typically used for in residential construction.

Question 22

Match the following conductor insulations with their temperature rating.
a.60°C
b.75°C
c.90°C
Type THHN

Question 23

Match the following conductor insulations with their temperature rating.
a.60°C
b.75°C
c.90°C
Type TW

Question 24

If the 1-1/4 in. (32 mm) distance from the edge of the hole to the edge of the framing member cannot be maintained, what thickness of steel plate must be used to protect the cable?

Question 25

The suffix "B" in Type NM-B nonmetallic cable means that the conductors have an insulation temperature rated ____.

A) 30°C (86°F)
B) 60°C (140°F)
C) 75°C (167°F)
D) 90°C (194°F)

Question 26

Explain what must be done if cable holes through studs cannot be bored to meet the requirements of the NEC or if cables are to be laid in notches or grooves cut into the face of the stud.

Question 27

Explain why particular care has to be taken when making aluminum wiring connections.

Question 28

What is the difference between Type NM-B and Type NMC-B cable?

Question 29

Explain what must be done when cables are bundled together for more than 24 inches.

Question 30

Lengths of flexible metal conduit longer than ____________________ feet are not acceptable as an equipment grounding conductor. In such cases a separate bonding jumper is required to run outside of the flexible conduit to maintain the continuity of the grounding path.

Question 31

The NEC recommends a voltage drop no greater than ____________________ percent for feeders and no greater than ____________________ percent total for feeders and branch circuits together.

Question 32

Although old fashioned knob-and-tube wiring is no longer used for new construction, NEC Article ____________________ applies when this wiring method is encountered during remodeling work.

Question 33

When fire stopping material is used where more than ____________________ nonmetallic sheathed cables pass through wood framing members, their ampacities must be adjusted, according to 310.15(B)(3)(a).

Question 34

The NEC specifies that 60°C ampacity be used for circuits rated 100 amperes or less, except when the equipment terminals are marked for use with higher temperature wire. What is one potential problem with using higher-temperature, higher-ampacity wire?

Question 35

Describe at least three effects of voltage drop in residences.

Question 36

Match the following conductor insulations with their temperature rating.
a.60°C
b.75°C
c.90°C
Type THWN

Question 37

Nonmetallic-sheathed cable is manufactured with copper conductors ranging in size from ____________________ AWG to ____________________ AWG and with aluminum or copper-clad aluminum conductors ranging in size from ____________________ AWG to ____________________ AWG.

Question 38

Although the National Electrical Code contains requirements for making holes and notches in framing members, in order to protect the cables installed in them, electricians must also be aware that ____________________ also have requirements for holes and notches in framing members, in order not to weaken the structure of the building.

Question 39

When Type NM cable is run through holes in metal framing members, ____________________ must be provided to protect the cable from sharp metal edges.