Code Quiz of Day

Minimum Length of Ground Rod Used With Communications Systems

Oct. 23, 2014

Grounding methods for communications systems are outlined in Part IV of Art. 800.

In one- and two-family dwellings where it is not practicable to achieve an overall maximum primary protector grounding conductor length of 20 ft, a separate ground rod not less than _____ in length shall be driven and it shall be connected to the power grounding electrode system with a 6 AWG conductor.

a) 5 ft
b) 8 ft
c) 10 ft
d) 20 ft

See answer and applicable Code reference

The correct answer is: a) 5 ft

Grounding methods for communications systems are outlined in Part IV of Art. 800. As noted in Sec. 800.100(A)(4), the length of the primary protector bonding conductor or grounding electrode conductor shall be as short as practicable, not to exceed 20 ft. However, the Exception in this section notes the following:

"In one- and two-family dwellings where it is not practicable to achieve an overall maximum primary protector bonding conductor or grounding electrode conductor length of 20 ft, a separate communications ground rod meeting the minimum dimensional criteria of 800.100(B)(3)(2) shall be driven, the primary protector shall be connected to the communications ground rod in accordance with 800.100(C), and the communications ground rod shall be connected to the power grounding electrode system in accordance with 800.100(D)."

About the Author

Mike Holt

Mike Holt is the owner of Mike Holt Enterprises (www.MikeHolt.com), one of the largest electrical publishers in the United States. He earned a master's degree in the Business Administration Program (MBA) from the University of Miami. He earned his reputation as a National Electrical Code (NEC) expert by working his way up through the electrical trade. Formally a construction editor for two different trade publications, Mike started his career as an apprentice electrician and eventually became a master electrician, an electrical inspector, a contractor, and an educator. Mike has taught more than 1,000 classes on 30 different electrical-related subjects — ranging from alarm installations to exam preparation and voltage drop calculations. He continues to produce seminars, videos, books, and online training for the trade as well as contribute monthly Code content to EC&M magazine.