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25 terms

Maintenance Electrician Exam #2

STUDY
PLAY
In computing the load of luminaires that employ ballast, transformers, or autotransformers, such as fluorescent lighting units, the load must be based on the _____.
a) total wattage of the lamps
b) VA of the lamps
c) length of the lighting fixture
d) ampere ratings of the complete units
D: ampere ratings of the complete units
Ref: 220.18(B)
A branch-circuit inverse-time circuit breaker rated in amperes shall be permitted as a controller for _____.
a) continuous-duty motors
b) intermittent-duty motors
c) torque motors
d) all motors
D: all motors
Ref: 430.83(A)(2)
Compliance with the provisions of the NEC® will result in an electrical installation that is essentially _____.
a) free from hazard
b) a good electrical system
c) an efficient system
d) all of these
A: free from hazard
Ref: 90.1(B)
Under normal conditions, an equipment grounding conductor will _____.
a) improve current flow
b) not carry current
c) carry current
d) reduce circuit resistance
B: not carry current
Ref: Art. 100; Trade Knowledge
Cord-and-plug-connected vending machines located in break rooms of commercial establishments are required to be provided with _____.
I) a power supply cord not smaller than size 12 AWG with a length not exceeding 4 feet.
II) GFCI protection
a) I only
b) II only
c) both I and II
d) neither I nor II
B: II only
Ref: 422.51
A motor with nine leads coming out of it is a _____.
a) two-phase motor
b) two-speed motor
c) dual-voltage motor
d) multi-speed motor
C: dual-voltage motor
Ref: Trade Knowledge
On a four-wire, delta-connected system, the conductor having the higher voltage to ground (high-leg) shall be identified as _____ in color, if the grounded conductor is also present to supply lighting or similar loads.
a) white
b) red
c) green
d) orange
D: orange
Ref: 110.15
When an electrical trade size 3⁄4 inch electrical metallic tubing (EMT) is in excess of 24 inches in length, the conduit is permitted to contain no more than _____ size 10 AWG conductors with THWN insulation.
a) six
b) ten
c) eight
d) fourteen
B: ten
Ref: Annex C, Tbl. C.1
Given: an electrical metallic tubing (EMT) 50 feet in length to be installed will contain a total of nine conductors. Six of these wires are considered to be current-carrying. What is the derating factor, in percent, that must be applied to the ampacity of the current-carrying conductors?
a) 80 percent
b) 70 percent
c) 60 percent
d) 50 percent
A: 80 percent
Ref: Tbl. 310.15(B)(2)(a)
The reason the NEC® requires all grounded and ungrounded conductors of a common circuit to be installed together in the same ferrous metal raceway is to reduce _____.
a) expense
b) inductive heat
c) voltage drop
d) resistance
B: inductive heat
Ref: 300.20(A)
In general, electrical metallic tubing (EMT) shall be securely fastened within ____ of each junction box, panelboard, or other conduit termination.
a) 3 feet
b) 6 feet
c) 8 feet
d) 10 feet
A: 3 feet
Ref: 358.30(A)
One horsepower is equal to _____ watts.
a) 746
b) 1,000
c) 1,250
d) 1,500
A: 746
Ref: General Knowledge
For continuous-duty motors, the motor nameplate current rating is used to determine the size of the _____ required for the motor.
a) disconnecting means
b) branch-circuit conductors
c) motor overload protection
d) short-circuit protection
C: motor overload protection
Ref: 430.6(A)(2)
In general, branch-circuit conductors that supply a single AC motor used in a continuous-duty application shall have an ampacity of NOT less than _____ percent of the motor's full-load running current rating.
a) 125
b) 100
c) 150
d) 115
A: 125
Ref: 430.22(A)
Unless listed and identified otherwise, terminations and conductors of circuits rated 100 amperes or larger shall be rated at _____.
a) 60 degrees C
b) 75 degrees C
c) 90 degrees C
d) 120 degrees C
B: 75 degrees C
Ref: 110.14(C)(1)(b)(1)
When circuit breakers are used to switch 120-volt and 277-volt, high-intensity discharge lighting branch-circuits, the circuit breakers shall be listed and marked _____.
I) SWD
II) HID
a) I only
b) II only
c) either I or II
d) neither I nor II
B: II only
Ref: 240.83(D)
An insulated branch circuit conductor with a continuous yellowcolored insulation is considered to be a/an _____.
a) equipment grounding conductor
b) grounded conductor
c) switch-leg
d) ungrounded conductor
D: ungrounded conductor
Ref: 310.12(C); 200.6; 250.119
When an insulated black conductor is identified by three continuous white stripes along its entire length, it is considered a/an _____.
a) grounded conductor
b) ungrounded conductor
c) equipment grounding conductor
d) phase of a delta-connected system
A: grounded conductor
Ref: 200.7(A)(2)
Given: a 9 kW rated 208-volt, three-phase electric steamer is to be installed in the kitchen of a commercial establishment, the steamer will draw _____ amperes.
a) 43
b) 4.3
c) 25
d) 75
C: 25
Ref: 3-Phase Cureent Formula
Sol: I = P/E x 1.732

I = (9 kw x 1,000) / (208 x 1.732) = 9,000 watts / 360.25 = 24.9 amperes
What is the approximate MAXIMUM distance a single-phase, 240-volt, 42-ampere load may be located from a panelboard, given the following related information: (1)copper conductors, K = 12.9; (2)size 8 AWG THWN/THHN conductors are used; (3)limit voltage drop to 3 percent
a) 50 feet
b) 110 feet
c) 160 feet
d) 195 feet
B: 110 feet
Ref: Chapter 9, Table 8; Distance Formula
Sol: VD = 240 volts x 3 percent = 7.2 volts

D = (CM x VD) / (2 x K x I) = (16,510 x 7.2) / (2 x 12.9 x 42) = 118,872 / 1,083.6 = 109.7 ft.
The NEC permits electrical trade size 3⁄8 inch flexible metal conduit (FMC) to be used for tap conductors (fixture whips) to luminaires, provided the length of the flex does not exceed _____.
a) 4 feet
b) 6 feet
c) 8 feet
d) 10 feet
B: 6 feet
Ref: 348.20(A)(2)c
The MINIMUM required width of the working space in front of panelboards, switchboards, disconnects, and motor controllers shall be the width of the equipment or _____ , whichever is greater.
a) 2 feet
b) 3 feet
c) 4 feet
d) 30 inches
D: 30 inches
Ref: 110.26(A)(2)
In general, branch-circuit conductors serving continuous loads, such as luminaires in an office building or commercial plant, shall have an ampacity of NOT less than _____ percent of the load.
a) 125
b) 115
c) 150
d) 80
A: 125
Ref: 210.19(A)(1)
A SPD (surge arrester or TVSS) device may be installed on circuits of up to _____ volts.
a) 150
b) 300
c) 600
d) 1,000
C: 600
Ref: 285.3(1)
In general, the overcurrent protection for size 12 AWG copper conductors, regardless of the insulation type, shall not exceed _____ amperes.
a) 15
b) 20
c) 25
d) 30
B: 20
Ref: 240.4(D)(5)