Q. A large number of satellite professionals ground the satellite system to the nearest available water hose bib. Does the NEC permit this installation practice?
A. No. The satellite mast (810.15) and discharge unit (ground block) [810.20(C)] must be grounded (actually bonded) in accordance with 810.20. The electrode that’s suitable for this purpose includes the nearest accessible [810.40(F)(1)]:
a. Building or structure grounding electrode system (250.50).
b. Interior metal water-piping system, within 5 feet from its point of entrance [250.52(A)(1)]. (see the Figure)
c. Accessible bonding means [250.94].
d. Metallic service raceway.
e. Service equipment enclosure.
f. Grounding electrode conductor or the grounding electrode conductor metal enclosure.
Grounding the lead-in antenna cables and the mast helps in preventing voltage surges from static discharge from reaching the inner conductor of the lead-in cable. Because the satellite sits outdoors, wind creates a static charge on the dish as well as the wire attached to it. This charge can build up on the dish and cable until it jumps across an air space, often through the electronics inside the LNBF or receiver. Grounding the coaxial cable and dish to the building grounding electrode system helps in dissipating this static charge.
Nothing can prevent damage from a direct lightning strike, but grounding these systems in accordance with the NEC with proper surge protection (not NEC required) can help reduce damage to satellite equipment as well as protect other related equipment from nearby lightning strikes.
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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.