Journeyman Electrician’s Exam Journeyman Electrician's Boxes and Enclosures 3

Question 1

Per NEC 314.20, in walls or ceilings constructed of combustible material (such as wood paneling), electrical boxes must be installed:

Accepted Answer

Flush with or projecting from the finished surface

Answer

Set back no more than 1/4 inch from the finished surface

Answer

Set back no more than 1/2 inch from the finished surface

Answer

Recessed at least 1/4 inch to allow for cover plate seating

Question 2

Per NEC 314.20, in noncombustible walls such as plaster or tile, what is the maximum allowable setback of an electrical box from the finished surface?

Accepted Answer

1/4 inch

Answer

0 inches — boxes must be flush

Answer

1/2 inch

Answer

1 inch

Question 3

According to NEC 314.23(B)(1), a box mounted without a direct structural connection must be fastened to a structural member within:

Accepted Answer

12 inches

Answer

6 inches

Answer

18 inches

Answer

24 inches

Question 4

A 4-11/16 inch square metal box 2-1/8 inches deep has a listed volume of 42 cubic inches. Using only 10 AWG conductors (no devices), how many conductors are permitted?

Accepted Answer

16 conductors

Answer

12 conductors

Answer

14 conductors

Answer

18 conductors

Question 5

Which of the following is a true statement regarding nonmetallic (plastic) electrical boxes used with nonmetallic-sheathed cable (NM)?

Accepted Answer

The equipment grounding path is carried by the EGC wire in the cable, not the box

Answer

Plastic boxes do not require volume markings

Answer

A separate metal ground screw is required inside the plastic box body

Answer

Nonmetallic boxes may not be used in any residential application

Question 6

Per NEC 314.15, boxes installed in wet locations must be:

Accepted Answer

Listed as weatherproof and suitable for the specific wet or damp location

Answer

Any NEMA 4X-rated enclosure regardless of listing

Answer

Sealed with silicone caulk around all conduit entries

Answer

Metallic only — nonmetallic boxes are prohibited in wet areas

Question 7

A metal box whose dimensions do not appear in NEC Table 314.16(A) must be marked with its cubic-inch volume so that the installer can:

Accepted Answer

Apply the conductor fill calculations of 314.16(B) for any wire size used

Answer

Verify the box meets UL listing requirements

Answer

Determine the correct torque specification for cover screws

Answer

Calculate the required short-circuit current rating of the box