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Michigan Journeyman practice test #4
Questions and Answers
1. High impedance grounded neutral systems in which a
grounding impedance, usually a resistor, limits the ground-fault
current to a low value shall be permitted for 3-phase ac systems
of___ volts to___, where only qualified persons service the
installation, ground detectors are installed on the system, and line-
to-neutral loads are not served. Ans: 480v-1000v 250.36
2. A 480-volt, 3-phase, 12,000 watt electric kiln draws___ amperes.
Ans: 14.45a
3. A 480 volt, 1-phase, 12,000 watt electric kiln draws___ amperes
Ans: 25a
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4. All of the following are methods to reduce clearing times of
fuses rated 1200 amps or higher except___ Ans: zone-selective
interlocking 240.67.B.1.2.3
5. There are six current-carrying conductors in a raceway
connected to 75° C rated breakers. Each wire has a 70 amp load
using THHN conductors. The minimum size conductors used are
#___AWG Ans: 4awg 110.14.C1a3 75 column derate*80% 11014.C
says use 90 column
6. What size THHN copper conductors are required to supply a 45
amp load where there are 6 current carrying conductors in a
raceway and the terminals at the equipment and OCPD are rated
75°C Ans: 6awg 110.14.C1a3 75 column derate*80% 11014.C says
use 90 column
7. What size THHN copper conductors are required to supply a 40
amp load where there are 6 current carrying conductors in a
raceway and the terminals at the equipment and OCPD are rated
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75°C Ans: 8awg 110.14.C1a3 75 column derate*80% 11014.C says
use 90 column
8. What size THHN copper conductors are required to supply a 55
amp load where there are 3 current carrying conductors in a
raceway and the terminals at the equipment and OCPD are rated
75°C Ans: 6awg 110.14.C1a3 75 column derate*80%
9. An overcurrent device rated___ amperes is needed for the
installation of a 4 wire, wye service with four 500 Kcmil THWN
copper conductors per phase Ans: 1200a 380*4=1520a 240.4.C
(round down) 240.6.A= 1200a (over 800a round down)
10. An overcurrent device rated at___ amps is needed for an
installation of a 4 wire, WYE service w 2 500 Kcmil THWN copper
conductors per phase. Ans: 800a 380*2=760a 240.4.B (800a and
under-round up)
© 2025 All rights reserved
Michigan Journeyman practice test #4
Questions and Answers
1. High impedance grounded neutral systems in which a
grounding impedance, usually a resistor, limits the ground-fault
current to a low value shall be permitted for 3-phase ac systems
of___ volts to___, where only qualified persons service the
installation, ground detectors are installed on the system, and line-
to-neutral loads are not served. Ans: 480v-1000v 250.36
2. A 480-volt, 3-phase, 12,000 watt electric kiln draws___ amperes.
Ans: 14.45a
3. A 480 volt, 1-phase, 12,000 watt electric kiln draws___ amperes
Ans: 25a
© 2025 All rights reserved
, 2 | Page
4. All of the following are methods to reduce clearing times of
fuses rated 1200 amps or higher except___ Ans: zone-selective
interlocking 240.67.B.1.2.3
5. There are six current-carrying conductors in a raceway
connected to 75° C rated breakers. Each wire has a 70 amp load
using THHN conductors. The minimum size conductors used are
#___AWG Ans: 4awg 110.14.C1a3 75 column derate*80% 11014.C
says use 90 column
6. What size THHN copper conductors are required to supply a 45
amp load where there are 6 current carrying conductors in a
raceway and the terminals at the equipment and OCPD are rated
75°C Ans: 6awg 110.14.C1a3 75 column derate*80% 11014.C says
use 90 column
7. What size THHN copper conductors are required to supply a 40
amp load where there are 6 current carrying conductors in a
raceway and the terminals at the equipment and OCPD are rated
© 2025 All rights reserved
, 3 | Page
75°C Ans: 8awg 110.14.C1a3 75 column derate*80% 11014.C says
use 90 column
8. What size THHN copper conductors are required to supply a 55
amp load where there are 3 current carrying conductors in a
raceway and the terminals at the equipment and OCPD are rated
75°C Ans: 6awg 110.14.C1a3 75 column derate*80%
9. An overcurrent device rated___ amperes is needed for the
installation of a 4 wire, wye service with four 500 Kcmil THWN
copper conductors per phase Ans: 1200a 380*4=1520a 240.4.C
(round down) 240.6.A= 1200a (over 800a round down)
10. An overcurrent device rated at___ amps is needed for an
installation of a 4 wire, WYE service w 2 500 Kcmil THWN copper
conductors per phase. Ans: 800a 380*2=760a 240.4.B (800a and
under-round up)
© 2025 All rights reserved
