Ster-L-Ray Preheat Ultraviolet Germicidal Lamps operated by a preheat-start circuit that employs a relatively compact and economical ballast. The preheat circuit requires four electrical connections per lamp and a slight to moderate delay is needed to start the lamp. Due to increased circuit complexity, reliability is regarded as slightly less than slimline or cold cathode instant start circuits. Ozone output 3.5.