All utility services shall be below ground, except that terminal boxes may be located above ground. If located within a street, the utilities shall be outside of the cartway except for required crossings. Lots which abut existing streets where overhead utility supply lines and service connections have heretofore been installed may be supplied with overhead utility services from these existing overhead lines. In the case of existing overhead utilities, however, should a road widening or an extension of service or other such condition occur as a result of the development and necessitate the replacement or relocation of such utilities, such replacement or relocation shall be underground, if in accordance with current State of New Jersey Board of Public Utilities regulations.