Section 61. A town acquiring a plant may provide by ordinance or by-law for the equitable assessment upon the owner or occupant of any premises of the cost, or any part thereof, of laying and maintaining pipes, conduits, conductors or other appliances thereon. Payment of such assessments shall not be compulsory, but it shall be a condition precedent to the supplying of gas or electricity to the occupants of such premises, and may be required before providing appliances therefor.