Many homeowners and businesses in southwestern Connecticut were in shock Wednesday after United Illuminating filed for a double digit increase in electric rates.If UI?s proposal is approved by the Connecticut Department of Public Utility Control, homeowner customers will be slapped with a 38 percent increase on their January 1. On average, that will add $42 to monthly bills. However, the number hurts even more for business owners who will be hit with a 60 percent hike. Storeowners say the rates will force them to raise their prices or cut back on store hours in order to cope.The decision will be revaluated after a six-month period when supply contracts are re-written. UI officials say further increases may take place at that time.