Daylight 5000K
PIR Motion Sensor Light Bulbs, 9W A19 Daylight, 2-Pack
A19 bulbs that light up for movement below them and go out 30 seconds later.
Light It Up on AmazonPIR or Radar: Choosing a Motion Sensor Light Bulb
Two kinds of sensor sit in the tip of a motion bulb, and the fixture decides which one you need. Here is how each sees, and where each one fails.
Two ways to see movement
A PIR bulb has a passive infrared eye. It does not send anything out. It reads the warmth of a body moving across its view and switches the light on. The U.S. Department of Energy describes the same sensors in its guide to lighting controls, and names the condition they need.
Infrared sensors detect temperature changes in a room, and work well where the entire room is within the sensor’s field of view.
U.S. Department of Energy, Federal Energy Management Program, How to Select Lighting Controls for Offices and Public Buildings (LT-8). Read 28 September 2026.
On a porch, the room is the patch of ground under the bulb. If the eye can see that patch, the bulb works. If a frosted or glass shade sits between them, it cannot see anything and stays dark.
A radar bulb works the other way round. It sends out a weak 4.0GHz signal and listens for the echo off anything that moves. Glass and thin plastic do not stop it. That is what lets our radar bulb sit inside a closed lantern.
Where each one goes
Match the sensor to the fixture first, and the room second. The table below lists every motion bulb we make, with the figures from each product page.
An open fixture or a bare socket in a garage takes either kind. A closed glass lantern takes only the radar bulb. A spot where the bulb hangs over a sidewalk used by others is better with PIR, for the reason in the next section.
| Bulb | Sensor | Watts | Lumens | Lumens per watt | Price per bulb |
|---|---|---|---|---|---|
| Radar motion bulbs | 4.0GHz radar | 15 | 1500 | 100 | $7.00 |
| PIR motion bulbs 9W | PIR infrared | 9 | 800 | 89 | $4.50 |
| PIR motion bulbs 12W | PIR infrared | 12 | 1100 | 92 | $5.09 |
Why a bulb lights for no one
Every motion sensor has the same weak spot, and the Department of Energy guide calls it out plainly for offices. It holds for porches too.
At the same time, “false-on” incidents can be triggered by an automatic on/off sensor that is exposed to passersby in an adjoining hallway.
U.S. Department of Energy, Federal Energy Management Program, How to Select Lighting Controls for Offices and Public Buildings (LT-8). Read 28 September 2026.
For a radar bulb, the adjoining hallway can be the other side of a wall, a busy street past the hedge, or a tree moving in the wind. A PIR bulb reacts only to warm bodies in view, so it wakes less often, but a cat on the porch still counts.
If a sensor bulb lights too often, move it or turn it so its view covers the path you use and little else. If it lights too rarely, check that no other light falls on it. A porch lamp next to a dusk-to-dawn sensor can convince it that night never came.
What none of them do
- They do not dim. Put a motion bulb on a dimmer and the sensor may flicker or fail.
- They do not work with a smart switch that cuts the power. The sensor needs the switch on.
- They do not replace a security camera. A light that turns on is a signal, not a record.
Sources we read
- U.S. Department of Energy, Federal Energy Management Program, How to Select Lighting Controls for Offices and Public Buildings (LT-8). Read 28 September 2026.
This guide is general information about home lighting. It is not medical, legal or safety advice.
GREENIC motion sensor bulbs in this guide
Daylight 5000K
PIR Motion Sensor Light Bulbs, 12W A19 Daylight, 2-Pack
A brighter PIR motion bulb: 12 watts, 1100 lumens, daylight white.
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