There are numerous photocontrol options that are available to improve longevity, performance, aesthetics or lineman "friendliness". Here are the most common photocontrol options.

Time delay
Hermetic Cell
Sealed Housing
Fail-OFF
Upward Facing
Dual Voltage
Button Control
High Temperature Controls
Custom Colors
Inverse Ratio
Projectile Resistant Controls
Higher Light Levels
Part Night Controls
Reverse Controls
Diagnostic controls

3.1 Time Delay

If a photocontrol has instantaneous response, it may turn-OFF when it sees a flash of light from a car headlight or a very long duration lightning flash. With a mercury vapor or metal halide fixture, this may cause the lamp to be out for several minutes for cool down, restrike and re-warm up. With high pressure sodium (HPS), restrike is often only several seconds and 90% warm up may be 1-2 minutes. In either case, roadway safety could be compromised. Also, hot restrikes may shorten the life of HPS and metal halide lamps.

To prevent unwanted turn-OFF problems, various time delay schemes are available from manufacturers to make a photocontrol "blind" to short light flashes. Ideally time delay acts to delay turn-OFF for 2-5 seconds and yet allows instant turn-ON for easy utility testing. This is easy to do in electronic controls and is offered by all manufacturers of electronic controls.

For Metal Halide Lighting, it is important to use time delay controls. With metal halide's 20-30 minute cool down and restrike time, you do not want lamps out at night due to inadvertent control switching. It is important to specify a control with repeatable time delay that works at all temperatures.