Motion sensor or dusk to dawn?
A motion sensor light stays dark until something moves in front of it, then shuts off a few minutes later. That suits a driveway, a back door or a path you walk now and then. A dusk-to-dawn light uses a small photocell to turn on at dark and off at sunrise, which suits a parking area or a building corner you want lit all night. Some fixtures do both: a low glow all night that brightens when someone walks up.
Aiming the light where it helps
Where the fixture goes matters as much as how bright it is. Mounted high and tilted down, a light covers the ground you walk on. Pointed outward, it shines into the street, a neighbor's bedroom window, or the eyes of whoever is pulling in. Most sensors also have adjustments for range and sensitivity, so a passing car or the neighbor's cat isn't setting them off all night. We set those when we install the light.
Replacing a fixture or adding a new spot
Swapping an old flood light for a motion sensor fixture is usually a quick job on the wiring that's already there. A new location takes more: a box on the wall, a wire run through the attic or along the siding, and sometimes a new circuit. Lights at a detached shop, barn, or gate need power out to that building first, which we cover on the shop, garage, and barn wiring page.
Lighting for businesses
For a storefront, office or shop building, we light entrances, walkways, parking, and the sides of the building, often on a photocell that turns them on at dark. If you're also updating the lights inside, see commercial LED retrofits.