Code Quiz: Article 250, Part 10

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 Codebookcity.com. He is a former editor of an electrical magazine were he edited Code articles.

1. When you drive ground rods, are you required to reach an earth resistance of 25 ohms or less?
    

2. If you have separate services feeding a building, should those be separately grounded?
    

3. Since air terminals are simply one end of the grounding path in a lightning protection system, you can use them as grounding electrodes also--is that correct?
    

4. Can metal waterpipe serve as a grounding electrode conductor?
    

5. Should you use aluminum or copper grounding electrode conductors if you have a cathodic protection system?