A.   All new for on private property and on public along shall be underground.
   B.   Where possible, existing poles shall be used to provide the required transition to underground service to new to scenic corridors. However, a new pole set in line with the existing overhead system when necessary to serve approved new is not deemed to be a new utility. Upgrades and reinforcements of existing overhead facilities is allowed to the extent that the total number of electrical circuits or communication cables is not increased. Relocation of overhead utility facilities required by public improvement districts along scenic corridors shall conform with existing franchise standards.
   C.   When an existing is expanded by 50% or more in or land area, new and existing to all portions of the shall be located underground. Incremental expansion shall be cumulative. Additions to single- dwellings are exempt from this standard.