Motion Sensor Flood Light Installation in Phoenix: What to Know

Motion sensor flood light installation in Phoenix looks like a simple swap, and sometimes it is. But we get plenty of calls about lights that turn on all night, never turn on at all, or were mounted to a box that was never meant to hold them. Most of those problems come from where the light went and how it was mounted, not from the light itself.

Replacing a light vs. adding a new location

If there's already a light on the garage or the back patio, putting a motion flood light in its place is usually straightforward: same box, same switch, new fixture. The box still has to be sound, mounted solidly and big enough for the connections, because twin-head floods and floodlight cameras weigh more than the porch light they replace.

A new location is a different job. Power has to come from somewhere: an existing lighting circuit with room to spare, or a new circuit from the panel. That usually means running cable through the attic, which in Phoenix is one of the hottest places you can work, and adding a box that's properly fastened to the structure through the stucco. New wiring like this is the kind of work that can need a permit; our electrical permit guide covers when.

Where to mount a security light

• Cover the approach, not the street. Aim at the driveway, side gate and back door, the places someone actually walks.
• Mount high enough to be hard to reach, usually under the eave or high on the wall, so nobody can unscrew the bulbs or turn the head.
• Point the heads down. A flood aimed level lights up your neighbor's bedroom and blinds anyone walking toward it.
• Match the fixture to the spot. Wall-mount and soffit (eave) mount fixtures are different. Check which one the light is listed for.
• Keep the sensor away from things that move or get hot: trees, bushes, pool water, AC condensers and dryer vents.

Why motion sensors act up in Phoenix

Most motion sensors on flood lights are passive infrared. They don't see movement the way a camera does; they notice a warm shape moving across a cooler background. That works well on a cool winter night. On a summer night when the block wall and driveway are still radiating heat from the day, there's less contrast between a person and the background, so some sensors get less responsive. Turning up sensitivity or re-aiming the sensor at a cooler surface, like gravel or a planted bed instead of the concrete, often helps.

The opposite problem is lights that keep turning on with nobody there. In Valley yards the usual causes are branches moving in the wind, a hot AC condenser kicking on in the sensor's view, car headlights sweeping across the yard, and monsoon gusts blowing debris. Narrowing the sensor's range, masking part of the lens if the fixture allows it, or moving the light usually fixes it.

The wall switch question

A motion flood light needs constant power to work, so the switch that controls it has to stay on. If someone in the house flips it off out of habit, the light is dead until it's flipped back. Many fixtures also use the switch for a manual override: a quick off-on can keep the light on until morning. Check your fixture's manual, because the sequence differs by brand. If the switch causes confusion, a labeled switch plate or a different switch arrangement can solve it.

If you're thinking about a smart switch for this light, be careful. Smart switches and motion fixtures can fight each other, and many older boxes have no neutral wire. Our post on smart switch installation explains what to check first.

Floodlight cameras

A floodlight camera is a flood light and a camera in one housing, and it usually installs where a light already is. It wants steady 120-volt power and decent Wi-Fi at the mounting spot. If you already have a video doorbell, our guide to video doorbell wiring covers the low-voltage side of the same setup. Electronics on a west or south wall sit in direct afternoon sun, so check the operating temperature range the maker lists and consider a spot under the eave where it gets shade.

Flood lights in Peoria and West Valley neighborhoods

A lot of homes in Peoria are in HOA communities, and many HOAs have rules about exterior fixtures and light that shines onto neighboring lots. Read your CC&Rs or ask the HOA before you buy, especially for bright twin-head floods on a two-story wall. Stucco is the other local detail: the fixture needs a proper box and mounting, and the edges need to be sealed so monsoon rain doesn't run behind it and into the wall.

Common mistakes we fix

• A heavy fixture hung from a thin box or straight off the stucco with no box at all.
• Indoor-rated fixtures outside, or a wall fixture installed on a soffit.
• Gaps at the top of the fixture that let rain run into the box.
• Splices made outside a box, or cable run along the outside wall without protection.
• New lights tapped into a circuit that's already loaded, causing nuisance trips.

If a new LED flood flickers or glows faintly when it should be off, the switch or the wiring may be the cause; our post on LED lights flickering walks through it. For yard and path lighting rather than security, see our landscape lighting guide. When you hire anyone for exterior wiring, you can look up their license on the Arizona Registrar of Contractors search.

Need flood lights installed or fixed?

Send us a photo of where you want the light and a photo of the existing fixture or box, if there is one. We'll tell you whether it's a simple swap or needs new wiring before we come out. B and D Electric LLC is licensed and bonded, Arizona ROC 361086, and our two owners have more than 40 years of combined experience. We handle lighting installation and residential electrical work across the Valley. Call or text (480) 828-1181, or request an estimate.