Any customer deposit required before commencement of service by a privately or publicly owned water, gas, telephone, cable television, electric light, heat, or power company shall be subject to the following:
(a) Upon termination of service with all bills paid, the deposit shall be returned to the customer within 45 days, less any deductions made in accordance with paragraph (c).
(b) Interest shall be paid on deposits in excess of $20. The rate of interest must be set annually and be equal to the weekly average yield of one-year United States Treasury securities adjusted for constant maturity for the last full week in November. The interest rate must be rounded to the nearest tenth of one percent. By December 15 of each year, the commissioner of commerce shall announce the rate of interest that must be paid on all deposits held during all or part of the subsequent year. The company may, at its option, pay the interest at intervals it chooses but at least annually, by direct payment, or as a credit on bills.
(c) At the time the deposit is made the company shall furnish the customer with a written receipt specifying the conditions, if any, the deposit will be diminished upon return.
(d) Advance payments or prepayments shall not be construed as being a deposit.