Florida utility companies are regulated under the authoprity of the Florida Public Service Commission. This is the Commission's (www.floridapsc.com) take on it...

When you apply for electric or gas service, the utility can ask that you establish credit by furnishing a cash deposit, a satisfactory guarantor to secure payment of bills, an irrevocable letter of credit from a bank, or a surety bond. If you furnish a cash deposit, the utility is required to pay six percent interest on the deposit if service is not terminated within six months. Residential deposits must be refunded after 23 months of service, provided that a prompt payment record has been established. To establish a prompt payment record, you cannot have (a) made more than one late payment for the proceeding 12 months, (b) paid with a bad check, (c) been disconnected for nonpayment, (d) tampered with the meter, or (e) used unauthorized service. Under certain circumstances, such as repeated late payment of bills or continued bills in excess of the amount of the current deposit, the company may require an additional deposit. However, the total amount of the requested deposit cannot exceed the average actual charge for electric or gas service for two billing periods for the most recent 12 month period. The company must give a 30-day written notice of an additional deposit request. When an account is closed, the deposit can be credited to the final bill and any balance must be refunded to you within 15 days.