Journeyman Electrician’s Exam Journeyman Electrician's Panelboards and Switchboards 1 — Questions and Answers
Question 1: Per NEC 408.4, every circuit and circuit modification must be legibly identified in a circuit directory. Where must this directory be located?
- On the inside of the panelboard door or inside the panelboard enclosure (Correct answer)
- On the exterior of the building near the main disconnect
- At the electrical service entrance equipment only
- Posted on the load side of the main breaker
Correct answer: On the inside of the panelboard door or inside the panelboard enclosure
NEC 408.4 requires the circuit directory to be posted on the face or inside the door of the enclosure or on the inside of the panelboard.
Question 2: According to NEC 408.15, a lighting and appliance branch-circuit panelboard is defined as one having more than what percentage of its overcurrent devices rated 30 amperes or less for which neutral connections are provided?
- 10 percent (Correct answer)
- 25 percent
- 50 percent
- 75 percent
Correct answer: 10 percent
NEC 408.15 defines a lighting and appliance branch-circuit panelboard as one having more than 10% of its overcurrent devices rated 30A or less with neutral connections.
Question 3: What is the maximum number of overcurrent devices permitted in a single lighting and appliance branch-circuit panelboard per NEC 408.15?
- 42 overcurrent devices (Correct answer)
- 30 overcurrent devices
- 60 overcurrent devices
- No limit is specified
Correct answer: 42 overcurrent devices
NEC 408.15 limits lighting and appliance branch-circuit panelboards to a maximum of 42 overcurrent devices, not counting the main overcurrent device.
Question 4: Per NEC 408.36, a panelboard must be protected by an overcurrent protective device having a rating not greater than which of the following?
- The rating of the panelboard (Correct answer)
- 125% of the panelboard rating
- The rating of the largest branch circuit breaker in the panel
- The calculated load plus 20% safety factor
Correct answer: The rating of the panelboard
NEC 408.36 requires the overcurrent protection for the panelboard to not exceed the panelboard's rated current capacity.
Question 5: Per NEC 408.36(D), a back-fed circuit breaker used as the supply overcurrent protective device for a panelboard must be:
- Secured in place by an additional fastener that requires other than a pull to release (Correct answer)
- Rated at 150% of the calculated load
- Installed with a lockout device on the breaker handle
- Replaced with a main lug only assembly
Correct answer: Secured in place by an additional fastener that requires other than a pull to release
NEC 408.36(D) requires back-fed devices to be secured with an additional fastener that requires more than a simple pull to release, preventing accidental removal under load.
Question 6: What is the minimum clearance required in front of a panelboard with exposed live parts on one side only (Condition 1) per NEC 110.26(A)(1)?
- 36 inches (Correct answer)
- 30 inches
- 42 inches
- 48 inches
Correct answer: 36 inches
NEC 110.26(A)(1) Condition 1 requires a minimum of 36 inches of clear working space in front of electrical equipment up to 150V to ground.
Question 7: Per NEC 110.26(A)(3), what is the minimum headroom required in working spaces for electrical equipment rated 600V or less?
- 6½ feet (78 inches) (Correct answer)
- 6 feet (72 inches)
- 7 feet (84 inches)
- 5½ feet (66 inches)
Correct answer: 6½ feet (78 inches)
NEC 110.26(A)(3) requires a minimum headroom of 6½ feet (78 inches) for working spaces around electrical equipment 600V or less.
