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NEC Quiz: Article 250, Part Nine

by Mark Lamendola

Quiz Questions

Code Quiz: Article 250, Part 9

Based on the 2008 NEC

Questions and answers written by Mark Lamendola, who has worked as a master electrician, electrical inspector, and design engineer. Mark is an IEEE Senior Member, and the Code article author for Since 1996, he has been writing National Electrical Code articles for electrical trade magazines and has an extensive portfolio of hundreds of NEC articles..

  1. What two conditions must a metal underground water pipe meet, if you use it as a grounding electrode?

  2. What's the minimum depth for a ground ring? Choose: 18 inches, 24 inches, 30 inches, 36 inches.

  3. What portion of the length of a driven rod must be in contact with the soil?

  4. What's the minimum depth for a plate electrode? Choose: 18 inches, 24 inches, 30 inches, 36 inches.

  5. What two requirements are auxiliary ground rods exempt from?

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