Rule 1. In the case of all underground extensions of electric distribution facilities as covered by these rules, the real estate developer or customer shall make a contribution in aid of construction to the utility in an amount equal to the estimated difference in cost between overhead and underground facilities. "Distribution facilities" means those operated at 15,000 volts or less to ground for ___ connected systems and 20,000 volts or less for delta connected systems.
Mich. Admin. Code R. 460.511