Any person, association or corporation engaged in the business of supplying electric light, heat or power within two or more counties of this state, and operating under franchises granted prior to April 10, 1969, may have the term of each franchise under which it is operating increased to not exceeding 50 years, including the unexpired portion of the term of such former franchise or franchises, by filing with the boards of county commissioners of the counties wherein such former franchise was granted and application in writing setting forth:
NRS 709.250