(a) A public utility may collect and retain a deposit for contracted recurring monthly service. A public utility that collects and retains a deposit of over $100 for recurring monthly service shall pay interest on that deposit at or before the time it is returned. Interest paid under this section shall be at the legal rate of interest at the time the deposit is made. However, if the deposit is placed in an interest bearing account, the utility shall pay the interest rate of the interest bearing account.
(b) If delinquent payments result in interruption of service, a public utility is not required to pay interest under (a) of this section for 12 months after reestablishment of service.