What length are the concrete-encased electrode reinforcement bars specified as part of the electrode definition?

• A. Two 10 ft bars
• B. One 8 ft bar
• C. Two 12 ft bars
• D. Three 10 ft bars

Answer: (A)

The length tested here is about the minimum total length of reinforcing steel in a concrete-encased electrode. The NEC requires at least 20 feet of reinforcing steel embedded in concrete to form this type of grounding electrode. If you use two bars, they must total at least 20 feet, so each bar needs to be 10 feet or longer. Two 10 ft bars meet the minimum exactly, which is why that option is correct. A single 8 ft bar doesn’t reach 20 feet, and three 10 ft bars would exceed the minimum, but the typical specification described for the electrode definition is two bars of 10 feet.