(a) The price to be charged to persons or corporations for gas or electricity shall be fixed and shall not be changed more often than once in three months. Any change shall take effect on the first day of the month, and the new price adopted shall, before the change takes effect, be advertised at least one month in some newspaper published in the municipality where the plant is located and, if none is published therein, in some newspaper published in the county where the plant is situated. Such price shall be fixed on a basis of not less than a net profit per year of five per cent on the cost of the investment in plant made by the municipality and also depreciation of the plant at not less than five per cent per annum of its cost, and the price shall not be greater than to allow a net profit of eight per cent per annum to the municipality on such cost. In fixing such basis on which to establish the price to be charged to persons and corporations, the gas and electricity used by the municipality shall be charged to it at cost. A sufficient deposit to cover the payment for gas or electricity for three months may be required in advance from any taker, and the supply may be shut off from any premises until all arrearages for gas or electricity furnished thereon are paid. Such deposit may be made by cash, letter of credit or surety bond. After three months’ default in payment of such arrearages, all appliances for distribution on such premises belonging to the municipality may be removed and after such removal shall not be restored, except on payment of all such arrearages and a sufficient sum to cover all expenses incurred by the removal and restoration, with the penalty which the municipality may impose in such cases.

(b) The provisions of this section shall not apply to the sale of compressed natural gas.

(c) Each member municipal electric utility of a municipal electric energy cooperative, as defined in § 7-233b, may return fifty per cent of the deposit, as described in subsection (a) of this section, to each nonresidential electric customer if such customer’s account remains in good standing for two years.