Section 76.70 - Exemption from input selector switch rules(a) In any case of cable systems serving communities where no portion of the community is covered by the predicted Grade B contour of at least one full service broadcast television station, or non-commercial educational television translator station operating with 5 or more watts output power and where the signals of no such broadcast stations are "significantly viewed" in the county where such a cable system is located, the cable system shall be exempt from the provisions of § 76.66 . Cable systems may be eligible for this exemption where they demonstrate with engineering studies prepared in accordance with § 73.686 of this chapter or other showings that broadcast signals meeting the above criteria are not actually viewable within the community.(b) Where a new full service broadcast television station, or new non-commercial educational television translator station with 5 or more watts, or an existing such station of either type with newly upgraded facilities provides predicted Grade B service to a community served by a cable system previously exempt under paragraph (a) of this section, or the signal of any such broadcast station is newly determined to be "significantly viewed" in the county where such a cable system is located, the cable system at that time is required to comply fully with the provisions of § 76.66 . Cable systems may retain their exemption under paragraph (a) of this section where they demonstrate with engineering studies prepared in accordance with § 73.686 of this chapter or other showings that broadcast signals meeting the above criteria are not actually viewable within the community.54 FR 25716, June 19, 1989