800.100 Cable and Primary Protector Grounding
Part IV. Grounding Methods
New FPN alerts the Code user that limiting the length of the grounding conductor for the primary protector should reduce voltages that may develop between the building’s power and communications systems during a lightning event.
(A) Grounding Conductor. The grounding conductor must be:
(4) Length. The grounding conductor must be as short as practicable. In one- and two-family dwellings, the grounding conductor cannot exceed 20 ft. Figure 800-2
FPN: Limiting the length of the grounding conductors reduce differences in potential between the building’s power and communications systems during lightning events.
Ex: Where it isn’t practicable to limit the grounding conductor to 20 ft for one- and two-family dwellings, a separate ground rod not less than 5 ft long [800.100(B)(2)(2)] with fittings suitable for the application [800.100(C)] must be installed. The additional ground rod must be bonded to the power grounding electrode system with a minimum 6 AWG conductor [800.100(D)].
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