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Illustrated Changes to the NEC, 2005 Edition - Part 2

Article 820

Community Antenna Television (CATV) and Radio Distribution Systems

820.100 Cable Grounding

Part IV. Grounding Methods

New FPN alerts the Code user that limiting the length of the grounding conductor should reduce voltages that may develop between the building’s power and communications systems during a lightning event.

(A) Grounding Conductor.
(4) Length. The grounding conductor must be as short as practicable.
In one- and two-family dwellings, the grounding conductor must not exceed 20 ft.
Figure 820-2

FPN: Limiting the length of the grounding conductors will help to reduce voltages between the building’s power and CATV systems during lightning events.

Ex: Where it isn’t practicable to limit the coaxial grounding conductor to 20 ft for one- and two-family dwellings, a separate ground rod not less than 8 ft long [820.100(B)(2)], with fittings suitable for the application [820.100(C)], must be installed. The additional ground rod must be bonded to the power grounding electrode system with a minimum 6 AWG conductor [820.100(D)].
Figure 820-3


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