The United Illuminating Company The United Illuminating Company (UI) is a New Haven-based regional electric distribution company established in 1899. UI is engaged in the purchase, transmission, distribution and sale of electricity and related services to more than 324,000 residential, commercial and industrial customers in the Greater New Haven and Bridgeport areas. At UI, we've always been dedicated to the communities we serve. That's why we provide more than electricity. We spearhead conservation efforts, encourage economic growth, assist area businesses and fund important charity organizations through established and often one-of-a-kind programs. With more than 100 years of service, the company is an independently owned and operated utility.