Using an Underground Metal Water Pipe as a Grounding Electrode

In order for a metal underground water pipe to be used as a grounding electrode, it shall be in direct contact with the earth for ______.

a) 5 ft
b) 10 ft or more
c) less than 10 ft
d) 20 ft or more

See answer and applicable Code reference

The correct answer is: b) 10 ft or more

Part III of Art. 250 focuses on the grounding electrode conductor and grounding electrode system. As per Sec. 250.52(A)(1), "A metal underground water pipe in direct contact with the earth for 10 ft or more (including any metal well casing bonded to the pipe) and electrically continuous (or made electrically continuous by bonding around insulating joints or insulating pipe) to the points of connection of the grounding electrode conductor and the bonding conductor(s) or jumper(s), if installed."

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