§ 117. Consumer deposits. Except as the right to require deposits is further limited by section thirty-six of this chapter, a gas corporation, an electric corporation, a gas and electric corporation, a water corporation, a steam corporation, a telegraph corporation, a telephone corporation or a municipality rendering equivalent utility services may, unless prohibited by the commission, require any person to whom such corporation or municipality shall supply gas, electric, water, steam, telegraph or telephone services to deposit a reasonable sum of money according to the estimated quantity of such services necessary to supply the same for two calendar months, to secure payment for such services actually rendered, or for the rental of fixtures, instruments and facilities actually supplied, but every such corporation and municipality shall allow to every such depositor interest at a rate per annum to be prescribed from time to time, at least annually, by the commission in the light of current economic conditions and current charges paid for other moneys borrowed by such corporation or municipality, and the expenses incurred by such corporation or municipality in obtaining, handling and returning or crediting the sum deposited, on the sum or sums so deposited, payable upon the return of the deposit or at earlier intervals as hereinafter prescribed. Whenever such deposit has been held for a period of one year, the interest accrued on such deposit shall be credited to the depositor on the first billing for utility service rendered after the next succeeding first day of October. If the depositor was not delinquent in the payment of any bill in such one year period, the deposit shall be refunded promptly at the end thereof, but without prejudice to the right to require a deposit thereafter in the event of a delinquency or where it can be shown that the financial condition of a business customer is such that it is likely that the customer may default in the future, and to retain such deposit for a prudent period; except that subject to such regulations as the commission may establish, if the deposit is for utility service rendered to a business, the deposit may be retained for a prudent period beyond such a one year period. No provider of utility services shall require of its customer within its service area a new security deposit where such customer was not required to post a security deposit or had a security deposit returned pursuant to this section and such customer establishes a new residence and continues service with the same provider of utility services.