In which conductor must the switching for three-way and four-way switches be done?
- Only in the grounded conductor
- In both of the circuit conductors
- In the equipment grounding conductor
- Only in the ungrounded conductor
Show the answer
D. Only in the ungrounded conductor
Three-way and four-way switches are wired so all switching is in the ungrounded conductor. Switching the grounded conductor would leave the load energized with respect to ground when it is off.
Reference: NEC 2023, 404.2(A)
A 120/240 V panelboard is 20 in. wide. What is the minimum width of the working space in front of it?
- 20 in.
- 24 in.
- 30 in.
- 36 in.
Show the answer
C. 30 in.
The working space must be as wide as the equipment or 30 in., whichever is greater. Matching the 20 in. width of the panel is the common mistake.
Reference: NEC 2023, 110.26(A)(2)
How do Chapters 5, 6 and 7 relate to the general rules found in the earlier chapters?
- They apply only where Chapter 8 refers to them
- They are informational and cannot be enforced
- They replace Chapters 1 to 4 for all occupancies
- They may supplement or modify the general rules
Show the answer
D. They may supplement or modify the general rules
Chapters 5, 6 and 7 cover special occupancies, special equipment and special conditions, and they can add to or change the general rules for those cases. They do not throw out the general chapters; the general rules still apply except where the special chapter changes them.
Reference: NEC 2023, 90.3