The LC4500 series photo controls feature low cost locking type mounting, and thermal type controls for street lighting and other applications requiring a twist and lock type plug connection. Thermal type photo controls provide dusk to dawn lighting control and a delay action, which eliminates loads switching off due to car headlights and lightning. The thermal type controls feature a cadmium sulfide photocell and polypropylene case to seal out moisture. The design utilizes a dual temperature compensating bimetal and composite resistor for reliable long life operation over ambient temperature extremes.