Grounded (Neutral) Conductors - Art. 200

Choose the best answer:

1. If you run one grounded (neutral) conductor in the same raceway as two ungrounded (phase) conductors, the grounded (neutral) conductor shall have an outer finish of white along its entire length if it has a maximum size of _____ or smaller.

(a) No. 6 (b) No. 4 (c) No. 2 (d) No. 1/0

2. You can use a conductor with black insulation as the grounded (neutral) conductor in a raceway, as long as it's at least _____ or larger and identified with white markings at its termination points.

(a) No. 6 (b) No. 4 (c) No. 2 (d) No. 1/0

3. You're permitted to use the white conductor of a nonmetallic sheathed cable in a switch loop as an ungrounded conductor ________.

(a) for a single-phase switch loop only (b) as the return from the switched outlet (c) as the supply to the switched outlet (d) all of the above

4. You shall identify an insulated conductor intended for use as a grounded (neutral) conductor, where contained in a flexible cord, by a ______ outer finish.

(a) white (b) natural gray (c) white or natural gray (d) None of the above

5. If your service-entrance conductors are rated at No. 250kcmil THWN copper, you must install a ______ copper grounded (neutral) conductor.

(a) No. 6 (b) No. 4 (c) No. 2 (d) No. 1/0

answers and discussion 1. (a), No. 6 conductor. When you use insulated conductors, No. 6 and smaller, as grounded (neutral) conductors, they shall be marked with a white or natural gray stripe or with three continuous white stripes on other than green insulation along their entire length.

Stallcup's Code Loop: Secs. 200-6(a) and 310-12(a).

2. (b), No. 4 conductor. If your insulated grounded (neutral) conductors are larger than No. 6, they are required to be identified by a white or natural gray stripe, or by three continuous white stripes on other than green insulation along their entire length, or by a distinctive marking (white) at the terminals during installation.

Stallcup's Code Loop: Secs. 200-6(b) and 310-12(a).

3. (c), as the supply to the switched outlet. When using nonmetallic-sheathed cable as the wiring method, you may use the white or natural gray conductor in the cable as a switch leg and the black conductor as the return leg (switch leg).

Stallcup's Code Loop: Secs. 200-7(c)(2) and 380-2(a).

4. (c), white or natural gray. The NEC requires you to identify an insulated conductor intended for use as a grounded (neutral) conductor (where contained within a flexible cord) by a white or natural gray outer finish or by three continuous white stripes on other than green insulation.

Stallcup's Code Loop: Secs. 200-6(c) and 400-22.

5. (c), No. 2 conductor. You must route the grounded (neutral) conductor with the ungrounded (phase) conductors. The grounded (neutral) conductor shall be no smaller than the required grounding electrode conductor per Table 250-66. However, it is not required to be larger than the largest ungrounded service-entrance (phase) conductor. Note that the grounded (neutral) conductor must also comply with Secs. 220-22 and 310-15(b)(4)(c).

Stallcup's Code Loop: Secs. 250-24(b)(1) and 250-142(a)(1), and Table 250-66.

Next month, we'll cover sizing disconnecting means for compressor motors.

Each quiz on the 1999 National Electrical Code is provided with Stallcup's Code Loops to show the direct correlation with other sections of the NEC. This allows the reader to review other sections of the NEC when determining if the correct answer to a problem is in one or multiple sections of the Code.