Hi/Lo Motion Activated Lighting
Hi/Lo Motion Activated Lighting

Hi/Lo (or High/Low) Motion activated lighting combines elements of two other kinds of lighting systems. These include dusk-to-dawn lighting in which lighting is operated continuously during nighttime hours and motion-activated lighting in which lights are activated when surrounding motion triggers a motion sensor. In a hi/lo system, the lights burn continuously at a low level and become brighter when a sensor detects motion.


As these lighting systems are a hybrid of two other types, they contain components of both dusk-to-dawn and motion-activated lighting. A ballast controls the change in light level. Consumers may choose from among various ballast varieties. One variable is the rate of change in light level. Stepped ballasts cause a sudden, noticeable change in light level, while dimming ballasts increase light gradually. Light levels typically available for stepped ballasts levels include a two-level variety with fifty percent and one hundred percent power and a three-level variety with thirty, sixty, and one hundred percent power levels.

Some people prefer continuous dimming in which the light level changes gradually from one hundred percent capacity to approximately ten percent of capacity. Stepped ballasts may be sufficient in many cases. Moreover, the sudden change of light may offer security advantages as a sudden change in light intensity may startle and confuse a would-be burglar. Dimming ballasts may be more preferable for indoor areas where sudden changes in light level are unwarranted and undesirable. Consumers should also note that dimming incandescent bulbs incurs a negative cost saving. Simply put, the rate of cost savings decreases as light intensity also decreases.

Fluorescent lamps are also used for these purposes, however reduced voltage incurred by dimming shortens the lifespan of the lamp. In addition, for outdoor security purposes, consumers should note that audible noise from fluorescent lamps may irritate neighbors. Fluorescent lamps also require precise tuning to their connected ballasts. Analog ballasts are more familiar and provide a few different levels of light dimming. Digital ballasts are more precise, allowing an exact amount of light preferred. As digital ballasts allow more precision, they are also more expensive.

Consumers should weigh the cost of different ballasts against their particular needs. Ballasts are also separated into how they conduct power. Magnetic dimming ballasts reduce light intensity to as low as ten percent, but they are only available for thirty and forty-watt bulbs. Electronic ballasts reduce light output to as low as one percent of total light intensity.


The lighting systems operate most of the night at a low level, usually an approximate twenty percent of their capacity, using a dimmer switch. However, when sensors detect motion, they automatically trigger the dimmer switch to a higher setting. Many experts recommend High-Intensity Discharge (HID) lighting paired with motion sensors. HID lighting requires time to reach full capacity but burns very brightly after reaching capacity. Thus, the lights remain on low and are already operating when the motion sensors detect a disruption in their detection fields. After the controller board activates the relay to the ballast intensifying the light level. In some cases, consumers may desire to illuminate different areas at different times at different intensities. In those cases, zone-switch lighting, in which different areas are lit at different times of evening may allow a maximum amount of lighting to be used where and when it is needed, thus avoiding over-illuminating areas where light is not needed. The most advanced systems available today offer multiple relays, regulated by microprocessors. These systems maximize control over the lighting system.


Consumers should take care to select the system that best fits their needs. The most expensive, complex system is not necessarily ideal as it certainly more expensive and may offer unnecessary features. Also, consumers should be aware of where they place their lights to avoid irritating their neighbors with sudden burst of light.