Measurements and Colors

Chapter 3 of the National Electrical Code provides rules related to wiring methods and materials, specifically the electrical wiring of branch circuits and feeders installed in premises wiring systems. Article 300 provides the general requirements while the other articles contain rules specifically related to wiring methods. How well do you know Chapter 3?

1. What is the minimum depth required for rigid metal conduit that is not installed under a 4-in. thick exterior slab?

Correct Answer: 6 in.

2. What is the minimum thickness of listed conduit sealing compound in a ½-in. conduit sealing fitting installed in a hazardous (classified) location?

Correct Answer: 5/8 in.

3. In a Class I, Division 1 location what is the maximum distance permitted for a conduit sealing fitting from an explosion-proof enclosure?

Correct Answer: 18 in.

4. What is the minimum size aluminum equipment grounding conductor for a 400-ampere feeder?

Correct Answer: 1 AWG

5. Completed wiring installations shall be free from short circuits, ground faults or any connections to ground other than as required or permitted elsewhere in the NEC.

Correct Answer: True

6. Unless otherwise permitted, armored-clad (Type AC cable) shall be secured within ______ of every outlet box, junction box, cabinet or fitting and at intervals not exceeding ______.

Correct Answer: 12 in., 4.5 ft.

7. Which of the following colors is not permitted for the branch circuits supplied by an isolated power system in the operating room of a hospital?

Correct Answer: Black

8. For other than elevators, an auxiliary gutter is not permitted to exceed ______ from the equipment it supplements.

Correct Answer: 30 ft.

9. For other than busway applications, switches shall be installed such that the center of the grip of the operating handle of the switch or circuit breaker, when in its highest position, is not more than ______ above the floor or working platform.

Correct Answer: 6 ft., 7 in.

10. Grounding electrode conductors shall be identified by the color green or identified with green marking tape at the terminations.

Correct Answer: False

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