Journeyman Electrician’s Exam Journeyman Electrician's Panelboards and Switchboards 3

Question 1

Per NEC 408.7, unused openings in panelboard enclosures must be:

Accepted Answer

Effectively closed to afford protection substantially equivalent to the wall of the enclosure

Answer

Covered with a listed bushing only

Answer

Sealed with electrical tape as a temporary measure

Answer

Left open only if smaller than ½ inch in diameter

Question 2

When installing a panelboard in a wet location, the enclosure must be weatherproof and installed with a minimum air space of how much between the enclosure and the mounting surface per NEC 312.2?

Accepted Answer

¼ inch (6 mm)

Answer

⅛ inch (3 mm)

Answer

½ inch (13 mm)

Answer

No air space is required if sealed with caulk

Question 3

Per NEC 408.36(A), individual main overcurrent protection for a lighting and appliance branch-circuit panelboard is not required when the panelboard feeder has overcurrent protection rated no greater than:

Accepted Answer

The panelboard's bus rating

Answer

125% of the panelboard's bus rating

Answer

The ampacity of the largest conductor in the panelboard

Answer

200 amperes regardless of the panelboard rating

Question 4

Per NEC 110.26(C), at least one entrance not less than 24 inches wide and 6½ feet high is required for rooms containing switchboards or panelboards rated:

Accepted Answer

1200 amperes or more and over 6 feet wide

Answer

800 amperes or more and over 4 feet wide

Answer

400 amperes or more regardless of width

Answer

Any rating if the room is used exclusively for electrical equipment

Question 5

When a panelboard is installed as a sub-panel in a detached garage fed from the main residential panel, the neutral conductor and equipment grounding conductor must be:

Accepted Answer

Kept separate and terminated on separate bars within the sub-panel

Answer

Bonded together at the sub-panel just as at the main panel

Answer

Run as a single combined conductor from the main panel

Answer

Terminated together only if the feeder is 240V with no neutral

Question 6

Per NEC 408.3(C), panelboards and switchboards must be mounted in a vertical position unless the equipment is specifically listed and marked for other orientations. The busbars in a panelboard shall be arranged to:

Accepted Answer

Provide phase identification and be plainly marked or color-coded

Answer

Run only horizontally to minimize thermal rise

Answer

Be concealed from view when the panel door is open

Answer

Match the color of the enclosure for aesthetic consistency

Question 7

Per NEC 240.24(D), overcurrent protective devices shall not be located in the vicinity of easily ignitable material. Which location is specifically prohibited for panelboard installation?

Accepted Answer

Clothes closets

Answer

Attached garages

Answer

Unfinished basements

Answer

Utility rooms