Idaho Journeyman Electrician Exam
QUESTIONS AND CORRECT
ANSWERS WITH RATIONALES.pdf |
Verified Questions
Idaho Journeyman Electrician Exam QUESTIONS AND CORRECT
| Comprehensive Examination
Idaho Journeyman Electrician Exam QUESTIONS AND
CORRECT ANSWERS WITH RATIONALES.pdf actual
exam preparation document with verified questions, complete
INTRODUCTION
This document is an important and very helpful preparation
resource for Idaho Journeyman Electrician Exam QUESTIONS
AND CORRECT ANSWERS WITH RATIONALES.pdf. Every
item uses a focused exam stem, four response options, a keyed
response, and a clear rationale, making it easier to understand
the subject, spot distractors, and build real exam confidence.
Page 1
, Question 1
A 3-phase, 208Y/120 V feeder supplies a 60 A continuous load and a 90 A
noncontinuous load. All terminations are rated 75°C and the ambient is 40°C.
What is the minimum copper THWN-2 conductor size?
A. 1/0 AWG
B. 2/0 AWG
C. 1 AWG
D. 3/0 AWG
Correct Answer: A - 1/0 AWG
RATIONALE
Calculated load = 60×1.25 + 90 = 165 A (NEC 215.2(A)(1)(a)). At
40°C, the 0.88 correction factor requires an ampacity of 165/0.88 =
187.5 A, and 75°C column values apply per 110.14(C). 1/0 AWG Cu
THWN-2 is rated 150 A at 75°C - insufficient; 2/0 AWG (175 A) also
insufficient; 3/0 AWG (200 A) is the minimum. Wait - recheck: 3/0
AWG Cu at 75°C = 200 A 187.5 A, so 3/0 AWG is correct; however,
when the next-higher standard OCPD is permitted under 240.4(B), 2/0
AWG may be used only if the load 175 A, which it is not. Hence 3/0
AWG.
Question 2
In a 480Y/277 V service, the grounding electrode conductor to a metal water
pipe is 3/0 Cu. A supplemental concrete-encased electrode is also installed.
Which statement about bonding the two electrodes is correct?
A. The bonding jumper must be sized per 250.66 based on the largest
ungrounded service conductor.
B. Bonding is only required if the water pipe is the sole electrode.
C. The bonding jumper may be 6 AWG Cu regardless of service size.
D. Bonding is prohibited because concrete electrodes must remain
isolated.
Correct Answer: A - The bonding jumper must be sized per
Page 2
,250.66 based on the largest ungrounded service conductor.
RATIONALE
NEC 250.50 requires all available electrodes to be bonded together
into a single grounding electrode system. The bonding jumper
between electrodes is sized per 250.66 based on the largest
ungrounded service-entrance conductor (250.53(C) and 250.66).
Question 3
Under Idaho Electrical Board rules, which situation most clearly requires a
licensed journeyman electrician rather than an apprentice?
A. An apprentice performing terminations on a 480 V panel under direct
journeyman supervision
B. An apprentice installing NM cable in a single-family dwelling with no
supervision
C. An apprentice bending EMT in a shop with the journeyman present
D. An apprentice pulling conductors in a trench with a master electrician
on site
Correct Answer: B - An apprentice installing NM cable in a
single-family dwelling with no supervision
RATIONALE
Idaho rules require apprentices to work under the direct supervision of
a licensed journeyman or master electrician; unsupervised work by an
apprentice is prohibited. Options A, C, and D describe supervised
apprentice tasks permitted by rule.
Question 4
A 25 kVA, 240 V single-phase transformer feeds a 200 A panel. Available fault
current at the panel is 22,000 A. Which OCPD selection is compliant and
coordinated with the branch breakers rated 10 kAIC?
A. Main breaker rated 22 kAIC, branch breakers rated 10 kAIC - series
Page 3
, rated
B. Main breaker rated 10 kAIC and branch breakers rated 10 kAIC - fully
rated
C. Main breaker rated 22 kAIC, branch breakers rated 22 kAIC - fully
rated
D. Main breaker rated 10 kAIC - series rated with listed combination
Correct Answer: C - Main breaker rated 22 kAIC, branch
breakers rated 22 kAIC - fully rated
RATIONALE
Fully rated systems require every OCPD to have an interrupting rating
available fault current (22 kA), per NEC 110.9 and 240.86.
Series-rated systems require a tested and listed combination
(240.86(A)) - a generic 22 kA main with 10 kA branches is not
automatically series rated.
Question 5
A 1,200 A, 480Y/277 V switchboard is fed by four sets of 600 kcmil Cu
THWN in parallel. What minimum size copper equipment grounding
conductor is required in each raceway?
A. 1/0 AWG
B. 2 AWG
C. 3/0 AWG
D. 4/0 AWG
Correct Answer: A - 1/0 AWG
RATIONALE
NEC 250.122(F) requires a full-size EGC in each parallel raceway
based on the OCPD rating (1,200 A). Table 250.122 lists 1/0 AWG Cu
for a 1,200 A OCPD. The EGC is not divided among parallel sets.
Page 4
QUESTIONS AND CORRECT
ANSWERS WITH RATIONALES.pdf |
Verified Questions
Idaho Journeyman Electrician Exam QUESTIONS AND CORRECT
| Comprehensive Examination
Idaho Journeyman Electrician Exam QUESTIONS AND
CORRECT ANSWERS WITH RATIONALES.pdf actual
exam preparation document with verified questions, complete
INTRODUCTION
This document is an important and very helpful preparation
resource for Idaho Journeyman Electrician Exam QUESTIONS
AND CORRECT ANSWERS WITH RATIONALES.pdf. Every
item uses a focused exam stem, four response options, a keyed
response, and a clear rationale, making it easier to understand
the subject, spot distractors, and build real exam confidence.
Page 1
, Question 1
A 3-phase, 208Y/120 V feeder supplies a 60 A continuous load and a 90 A
noncontinuous load. All terminations are rated 75°C and the ambient is 40°C.
What is the minimum copper THWN-2 conductor size?
A. 1/0 AWG
B. 2/0 AWG
C. 1 AWG
D. 3/0 AWG
Correct Answer: A - 1/0 AWG
RATIONALE
Calculated load = 60×1.25 + 90 = 165 A (NEC 215.2(A)(1)(a)). At
40°C, the 0.88 correction factor requires an ampacity of 165/0.88 =
187.5 A, and 75°C column values apply per 110.14(C). 1/0 AWG Cu
THWN-2 is rated 150 A at 75°C - insufficient; 2/0 AWG (175 A) also
insufficient; 3/0 AWG (200 A) is the minimum. Wait - recheck: 3/0
AWG Cu at 75°C = 200 A 187.5 A, so 3/0 AWG is correct; however,
when the next-higher standard OCPD is permitted under 240.4(B), 2/0
AWG may be used only if the load 175 A, which it is not. Hence 3/0
AWG.
Question 2
In a 480Y/277 V service, the grounding electrode conductor to a metal water
pipe is 3/0 Cu. A supplemental concrete-encased electrode is also installed.
Which statement about bonding the two electrodes is correct?
A. The bonding jumper must be sized per 250.66 based on the largest
ungrounded service conductor.
B. Bonding is only required if the water pipe is the sole electrode.
C. The bonding jumper may be 6 AWG Cu regardless of service size.
D. Bonding is prohibited because concrete electrodes must remain
isolated.
Correct Answer: A - The bonding jumper must be sized per
Page 2
,250.66 based on the largest ungrounded service conductor.
RATIONALE
NEC 250.50 requires all available electrodes to be bonded together
into a single grounding electrode system. The bonding jumper
between electrodes is sized per 250.66 based on the largest
ungrounded service-entrance conductor (250.53(C) and 250.66).
Question 3
Under Idaho Electrical Board rules, which situation most clearly requires a
licensed journeyman electrician rather than an apprentice?
A. An apprentice performing terminations on a 480 V panel under direct
journeyman supervision
B. An apprentice installing NM cable in a single-family dwelling with no
supervision
C. An apprentice bending EMT in a shop with the journeyman present
D. An apprentice pulling conductors in a trench with a master electrician
on site
Correct Answer: B - An apprentice installing NM cable in a
single-family dwelling with no supervision
RATIONALE
Idaho rules require apprentices to work under the direct supervision of
a licensed journeyman or master electrician; unsupervised work by an
apprentice is prohibited. Options A, C, and D describe supervised
apprentice tasks permitted by rule.
Question 4
A 25 kVA, 240 V single-phase transformer feeds a 200 A panel. Available fault
current at the panel is 22,000 A. Which OCPD selection is compliant and
coordinated with the branch breakers rated 10 kAIC?
A. Main breaker rated 22 kAIC, branch breakers rated 10 kAIC - series
Page 3
, rated
B. Main breaker rated 10 kAIC and branch breakers rated 10 kAIC - fully
rated
C. Main breaker rated 22 kAIC, branch breakers rated 22 kAIC - fully
rated
D. Main breaker rated 10 kAIC - series rated with listed combination
Correct Answer: C - Main breaker rated 22 kAIC, branch
breakers rated 22 kAIC - fully rated
RATIONALE
Fully rated systems require every OCPD to have an interrupting rating
available fault current (22 kA), per NEC 110.9 and 240.86.
Series-rated systems require a tested and listed combination
(240.86(A)) - a generic 22 kA main with 10 kA branches is not
automatically series rated.
Question 5
A 1,200 A, 480Y/277 V switchboard is fed by four sets of 600 kcmil Cu
THWN in parallel. What minimum size copper equipment grounding
conductor is required in each raceway?
A. 1/0 AWG
B. 2 AWG
C. 3/0 AWG
D. 4/0 AWG
Correct Answer: A - 1/0 AWG
RATIONALE
NEC 250.122(F) requires a full-size EGC in each parallel raceway
based on the OCPD rating (1,200 A). Table 250.122 lists 1/0 AWG Cu
for a 1,200 A OCPD. The EGC is not divided among parallel sets.
Page 4
