Designing with Light

DAYLIGHT SENSORS. These are simply photocells that react to daylight. When it’s dark, the photocell sends power to the light fixture it’s connected to; come dawn, the sensor opens the circuit, shutting down the fixture. You can install fixtures with built-in photocells or buy sensors separately.

Several retrofits are shown in the facing page. The most common type is a large photocell mounted directly onto a knockout in an outdoor fixture box. You can also buy a simple screw-base adapter with built-in sensor that fits a standard bulb socket; the bulb screws into the adapter. Or opt for a discreet photo eye designed to fit a hole drilled in a lamppost.

MOTION SENSORS. Handy both for security and for unloading a batch of groceries after dark, these “remote eyes” come in two basic versions: infrared and microwave. Some units combine both wave types. Like daylight sensors, motion sensors can be purchased alone or integrated into a fixture that houses one or more floodlights.

Plan to install the motion sensor on a house wall, eaves, or a freestanding post, no higher than about 12 feet off the ground. The trick is aiming the sensor’s detection lobes or waves. Don’t align them so they’re parallel to the most likely traffic path (for example, a front walkway); there are “dead spots” between the parallel detection bands. Instead, place the sensor so the lobes will cut across the traffic areas.

Some motion sensors have adjustable ranges of sensitivity and can be set to remain on for varying lengths of time. Achieving just the right combination of aim, response level, and duration will probably take some trial and error.

TIMERS. If your outdoor lighting circuit begins indoors, you can control it with the switches and timers. But if your system connects outdoors, choose one of the hardier outdoor timers.

There’s nothing fancy about the gunmetal gray timer, it turns lights and other electrical devices on and off once a day. But it can handle heavy loads (up to 4,100 watts); it has a rugged, driptight housing that withstands abuse; and you can lock the cover.

If you have a string of plug-in outdoor lights (such as Christmas lights, decorative patio lights, or rope lights), attach the digital sensor/timer combo to the side of your house, plug it into an outlet, and then plug the lights into the unit. You can control the lights with the daylight sensor, the timer, or the manual ON/OFF switch.