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Code Q&A

Feb 1, 2002 12:00 PM, By Mike Holt, NEC Consultant

Knowing how important NEC issues are to our readers, we're introducing a new online Code Q&A column. Updated weekly, visit this link for answers to your latest Code questions and concerns.

Q. I represent a large multifamily management company. Many of our residents want to install small satellite dishes in their apartments. Our policy is the dish must be installed per the manufacturer’s installation procedures, which references the NEC. Additionally, our policy states that all wiring must stay within the tenants "rented" space, in this case the patio or balcony. Given these parameters, how can a small satellite dish be grounded properly per the NEC and still be installed in accordance with our management policy?

A. There is no way to comply with the requirements set forth in the 2002 NEC and meet your management’s policy. In fact, your management policy is in violation of the Satellite Consumer Bill of Rights, a regulation released by the FCC on August 6, 1996. This regulation supercedes area zoning ordinances and Homeowner Association covenants and restrictions on DBS dish antennas. For more specific information, please contact the Satellite Broadcasting & Communications Association at (703) 549-6990, and/or the Federal Communications Commission at (202) 418-0163.

Q. I’m installing a Satellite TV system (18" DSS) near the electrical service. Is it okay to ground the dish mast and the coax grounding blocks to the same rod used for the electrical service, or do I have to install a new 8-ft grounding rod for the dish mast, as per the manufacturer’s instructions?

A. DO NOT add an independent ground rod in accordance with the installation instructions, they are wrong. You can use the same ground rod as the service ground rod as you suggested [810.21(F)(1)(a)].

Q. Many apartments and condominiums have a 15A or 20A, 125V receptacle on the balcony/patio. Could a connection be made to the ground in this receptacle, which is continuous back to the electrical circuit panel, to ground a satellite dish and its cable?

A. No. [see 810.21(F)(1)]

How to Ground a Satellite Dish and the Lead-In Cables In Accordance with the NEC

The lead-in cable from an "outdoor antenna" must be equipped with a listed antenna discharge unit (grounding block) located as near as practicable to the entrance of the conductors to the building (810.20). The cable discharge unit (810.21) and the mast (Dish) [810.15] must be grounded in accordance with 810.21(F)(1)(a) through (f) with a 10 AWG copper conductor that is run in as straight a line as practicable [810.21(E)].

If the grounding conductor to the electrode is run in a metal raceway, both ends of the metal raceway must be bonded to the grounding conductor [810.21(D)]. When an electrode, such as a ground rod, is installed to ground the mast or lead-in cable, it must be bonded with a 6 AWG copper conductor to the grounding electrode system at the building or structure served [810.21(J)].

If the lead-in from an outdoor antenna is not properly earth grounded, the receiver can be destroyed by voltage surges caused by nearby lightning strikes. If the mast is not properly grounded, the Low Noise Block (LNB) and the DC rotor motors that control the positioning of larger satellite dishes can also be destroyed.

Q. I want to install a 2-way satellite system on the patio of my third-floor apartment, which is enclosed on three sides. The installer wants to ground the dish and the coaxial cable to a ground rod at ground level. Can I use the metal water pipe in my apartment instead?

A. You are not permitted to use a metal rod driven into the earth to ground the dish and lead-in cable unless the rod is bonded to the building grounding electrode system with a 6 AWG conductor in accordance with 810.21(J). In addition, the 2002 NEC doesn’t allow you to use the local water pipe [810.21(F)(1)(b)] because it isn’t located within 5 ft of the point of entrance into the building.

Q. How far from the entrance to a bedroom can the light switch be after entering the room?

A. The NEC doesn’t specify a distance, but it would be nice if they were installed near the door entrance.

Q. How far from a shower or tub must a switch or receptacle be located?

A. The NEC doesn’t specify a distance—just don’t put them inside the shower or bathtub space [404.4 and 406-8(C)].

Q. Is there a minimum mounting height for a 277V or 480V metal-halide floodlight fixture outdoors if the system voltage is 480/277V, 4-wire, three-phase.

A. No, but outdoor lighting fixtures on circuits exceeding 120V nominal (between conductors) and not exceeding 277V nominal (to ground) must be located no less than 3 ft from windows, platforms, fire escapes, and the like [225.7(C)].