NEW MEXICO EL 1J ELECTRICAL
DISTRIBUTION JOURNEYMAN EXAM
QUESTIONS AND ANSWERS
1. When installing a 12.47kV overhead distribution line, what is the minimum vertical
clearance from the ground for a conductor crossing a public street per NESC requirements?
A. 15.5 feet
B. 12.5 feet
C. 20.5 feet
D. 18.5 feet
Answer: D
Conceptual Explanation: The NESC (National Electrical Safety Code) generally requires a
minimum clearance of 18.5 feet for 12.47kV lines crossing public streets and roads.
2. Which of the following describes the ‘Step Potential’ in the context of high-voltage
distribution safety?
A. The voltage difference between the hands and the feet.
B. The voltage required to jump an air gap of one foot.
,C. The total voltage of the distribution line relative to the neutral.
D. The voltage difference between two points on the ground separated by the distance of
one pace.
Answer: D
Conceptual Explanation: Step potential is the voltage difference between two points on
the ground separated by one pace (approx. 1 meter) when a ground fault occurs.
3. A three-phase transformer bank consists of three single-phase transformers connected in
Delta-Wye. If the primary line-to-line voltage is 13,800V and the secondary line-to-line
voltage is 208V, what is the turns ratio of each transformer?
A. 115:1
B. 66:1
C. 38.5:1
D. 19.2:1
Answer: A
Conceptual Explanation: In a Delta-Wye bank, the primary winding sees the full line-to-
line voltage (13,800V). The secondary winding (in Wye) sees the phase-to-neutral voltage
(.732 = 120V). 13, = 115.
, 4. According to NEC Article 250, what is the minimum size for a copper grounding electrode
conductor for a service with 500 kcmil copper service-entrance conductors?
A. #2 AWG
B. #4 AWG
C. 1/0 AWG
D. 2/0 AWG
Answer: C
Conceptual Explanation: Table 250.66 specifies that for copper service-entrance
conductors between 350 and 600 kcmil, a 1/0 AWG copper grounding electrode conductor
is required.
5. What is the primary purpose of a ‘Recloser’ in a distribution system?
A. To step down voltage for residential customers.
B. To measure energy consumption at a substation.
C. To automatically restore power after a temporary fault.
D. To isolate the neutral from the ground.
Answer: C
Conceptual Explanation: Reclosers are circuit breakers designed to sense overcurrents
and automatically reclose after a trip to clear temporary faults like tree branches touching
lines.
DISTRIBUTION JOURNEYMAN EXAM
QUESTIONS AND ANSWERS
1. When installing a 12.47kV overhead distribution line, what is the minimum vertical
clearance from the ground for a conductor crossing a public street per NESC requirements?
A. 15.5 feet
B. 12.5 feet
C. 20.5 feet
D. 18.5 feet
Answer: D
Conceptual Explanation: The NESC (National Electrical Safety Code) generally requires a
minimum clearance of 18.5 feet for 12.47kV lines crossing public streets and roads.
2. Which of the following describes the ‘Step Potential’ in the context of high-voltage
distribution safety?
A. The voltage difference between the hands and the feet.
B. The voltage required to jump an air gap of one foot.
,C. The total voltage of the distribution line relative to the neutral.
D. The voltage difference between two points on the ground separated by the distance of
one pace.
Answer: D
Conceptual Explanation: Step potential is the voltage difference between two points on
the ground separated by one pace (approx. 1 meter) when a ground fault occurs.
3. A three-phase transformer bank consists of three single-phase transformers connected in
Delta-Wye. If the primary line-to-line voltage is 13,800V and the secondary line-to-line
voltage is 208V, what is the turns ratio of each transformer?
A. 115:1
B. 66:1
C. 38.5:1
D. 19.2:1
Answer: A
Conceptual Explanation: In a Delta-Wye bank, the primary winding sees the full line-to-
line voltage (13,800V). The secondary winding (in Wye) sees the phase-to-neutral voltage
(.732 = 120V). 13, = 115.
, 4. According to NEC Article 250, what is the minimum size for a copper grounding electrode
conductor for a service with 500 kcmil copper service-entrance conductors?
A. #2 AWG
B. #4 AWG
C. 1/0 AWG
D. 2/0 AWG
Answer: C
Conceptual Explanation: Table 250.66 specifies that for copper service-entrance
conductors between 350 and 600 kcmil, a 1/0 AWG copper grounding electrode conductor
is required.
5. What is the primary purpose of a ‘Recloser’ in a distribution system?
A. To step down voltage for residential customers.
B. To measure energy consumption at a substation.
C. To automatically restore power after a temporary fault.
D. To isolate the neutral from the ground.
Answer: C
Conceptual Explanation: Reclosers are circuit breakers designed to sense overcurrents
and automatically reclose after a trip to clear temporary faults like tree branches touching
lines.
