Quiz: Building From the Ground Up

1. Only the requirements in Part X of Article 250 apply to systems and circuits over 1,000V.

2. The neutral conductor of a solidly grounded neutral system over 1,000V shall be not less than _____% of the ampacity of the phase conductors.

3. The neutral conductor of a solidly grounded neutral system shall have an insulation rated for at least _____.

4. Generally, what is the maximum distance between grounding points on a multigrounded neutral installation?

5. The grounding electrode system for an AC substation is required to comply with Part III of Article 250.

6. Metal fences within _____ feet of exposed electrical conductors or equipment in an AC substation are required to be bonded to the grounding electrode system using wire-type bonding jumpers.

7. All exposed conductive metal structures in or around a substation—including guy wires within 21/2 m (8 feet) vertically or 5 m (16 feet) horizontally of exposed conductors or equipment and subject to contact by people—shall be bonded to the grounding electrode systems in the area.

8. What minimum size copper grounding electrode conductor is required for a single-point grounded AC system secondary in a substation, if the secondary ungrounded derived conductors are sized at 250 kcmil, aluminum? The grounding electrode system is in-ground metal structures and multiple ¾-inch by 10-foot-long ground rods.

9. The number of transformers permitted in an AC substation _____.

10. The minimum size copper equipment grounding conductor for an AC substation feeder protected by a 200A protective relay shall not be smaller than _____ AWG.