Exam (elaborations)
Electrical Code Calculations, Level I (1-4) (1)
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- NBE SCIENCE
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- NBE SCIENCE
Electrical Code Calculations, Level I (1-4) (1)
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Electrical Code Calculations, Level I (1-4)1.08
.82
.88
.94 - ANS-Where types of insulated conductors from Table 310.16 are installed in other than
30°C ambient temperature areas, match the following insulated conductors to the proper
ambient temperature correction factor using Table 310.15(B)(1).
107 A - ANS-What is the ampacity of a 1 AWG THW copper conductor installed in a raceway
located in an ambient temperature of 110°F? Calculate to the nearest ampere.
117 A - ANS-Three 1/0 AWG XHHW-2 aluminum conductors are installed in a rigid metal
conduit, Type RMC, in an ambient temperature of 105°F. All of the conductors are
current-carrying conductors. Determine the ampacity of the current-carrying conductors.
Calculate to the nearest ampere.
134 A - ANS-Nine 3/0 AWG THHN aluminum conductors are installed in a three-inch RMC in an
area with an ambient temperature of 35°C. Only six of the conductors are current-carrying
conductors. Determine the ampacity of the 3/0 AWG conductors for this application. Calculate to
the nearest ampere.
14 A - ANS-Twelve 12 AWG THHN copper conductors are installed in a one-inch EMT in an
ambient temperature of 32°C. These twelve conductors are comprised of three 4-wire multiwire
branch circuits. The multiwire branch circuits are supplied by a 4-wire, 3-phase, wye-connected
system. The major portion of the load for each multiwire branch circuit consists of nonlinear
loads. Determine the ampacity of each of the 12 AWG conductors. Calculate to the nearest
ampere.
15 A - ANS-A 14 AWG XHHW-2 copper conductor is connected to a circuit breaker with
termination temperature limitation marked (not to exceed) 60°C. What is the ampacity of this
conductor now that it is connected to this circuit breaker?
15 A - ANS-Twenty 10 AWG THWN aluminum current-carrying conductors are installed in the
same conduit in an ambient temperature of 30°C. Determine the ampacity of each of the
current-carrying conductors. Calculate to the nearest ampere.
175 A - ANS-A 3-phase, 4-wire feeder supplies a continuous load of 75 amperes and a
noncontinuous load of 75 amperes to a second floor equipment distribution switchboard.
186 A
94 A
, 346 A
191 A - ANS-The following conductors are installed in rigid metal conduit in an ambient
temperature of 40°C. Using Table 310.18, identify the correct ampacity for these insulated
conductors.
198 A
142 A
629 A - ANS-The following conductors are installed open in free air, with an ambient
temperature of 40°C. Using Table 310.19, identify the correct ampacity for these insulated
conductors.
1AWG
3AWG
3AWG - ANS-The calculated load for a 3-phase, 480-volt circuit is 98 amperes. Each installation
consists of three single insulated copper conductors in rigid metal conduit, Type RMC. Identify
the correct copper conductor size needed for each insulation type.
20 A - ANS-An existing 12 AWG TW copper conductor is connected to a new replacement
circuit breaker with termination temperature limitation marked (not to exceed) 60/75°C. What is
the ampacity of this conductor now that it is connected to this circuit breaker?
20 A - ANS-Twelve 12 AWG THHN copper conductors are installed in a one-inch EMT in an
ambient temperature of 32°C. These twelve conductors are comprised of three 4-wire multiwire
branch circuits. The multiwire branch circuits are supplied by a 4-wire, 3-phase, wye-connected
system. The neutral conductor in each of these multiwire branch circuits carries only the
unbalanced current from the other conductors in each respective multiwire branch circuit.
Determine the ampacity of each of the 12 AWG conductors. Calculate to the nearest ampere.
25 A - ANS-Two 3-phase, 4-wire multiwire branch circuits supply LED lighting loads from a
3-phase, 4-wire, wye system. The branch circuits consist of eight 10 AWG THWN copper
conductors installed in EMT in an ambient temperature of 86°F. Determine the ampacity of the
10 AWG conductors in this application. Calculate to the nearest ampere.
25.5 - ANS-The minimum cubic inch (in.3) capacity of a box that contains six 14 AWG and six
12 AWG conductors is ? .
30 A - ANS-A 10 AWG THWN copper conductor is connected to a circuit breaker with
termination temperature limitation marked (not to exceed) 60°C. What is the ampacity of this
conductor now that it is connected to this circuit breaker?
32 A - ANS-Two "A" phase conductors, two "B" phase conductors, and two neutrals are installed
as two 3-wire multiwire branch circuits of a 120/208-volt system. They are installed in EMT in an
ambient temperature of 30°C. The conductors are 10 AWG THHN copper. What is the ampacity
of each of the current-carrying conductors? Calculate to the nearest ampere.
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