Deter
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Depart
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[] My home has interior motion sensors placed in key areas so that if someone gets inside while the system is armed, the alarm is triggered immediately.
What a Motion Sensor Actually Does
A motion sensor detects movement inside your home.
Most modern sensors use passive infrared (PIR) technology, which senses changes in heat as a person moves through a space.
When triggered, it:
- Sends an alert to your system
- Sounds the alarm (if enabled)
- Notifies the monitoring center
Unlike door/window sensors or glass break sensors, motion sensors don’t care how someone got in.
They only care that someone is moving inside your home who shouldn’t be.
Why This Matters
No system is perfect.
- A door sensor could fail
- A window might be left unlocked
- A glass break sensor might miss an edge case
- Someone could enter through an unusual access point (garage, basement, etc.)
Motion sensors exist for one reason:
If everything else fails, this still catches them.
Without motion sensors, an intruder who avoids your perimeter detection could move freely inside your home.
With motion sensors, they trigger the alarm the moment they step into a monitored space.
Where Motion Sensors Should Go
Motion sensors are most effective when they cover natural paths of movement inside the home.
Think like an intruder:
- Where would someone walk after entering?
- What paths lead deeper into the home?
High-value placement areas:
- Main hallways
- Entry paths from doors
- Bottom or top of staircases
- Large open living areas
- Between bedrooms and the rest of the house
Avoid placing them randomly.
They should be positioned so that it’s hard to move through the house without being seen.
What Motion Sensors Are NOT
Motion sensors are not your primary detection.
They are not:
- A replacement for door/window sensors
- A replacement for glass break sensors
- A perimeter defense
They are your last line of detection before Depart or Defend.
If your motion sensor is the first thing detecting an intruder, your system is already behind.
Common Mistakes
- Relying on too few sensors
One sensor in a corner won’t cover your home. - Poor placement
Pointing it at a wall instead of across a path of travel reduces effectiveness. - Ignoring blind spots
Furniture, walls, and layout can block detection. - Turning them off at night
Many people disable motion sensors while sleeping.
That removes your backup layer when you need it most.
Pets and Motion Sensors
Modern motion sensors can be pet-immune, typically ignoring animals under a certain weight (e.g., 40–80 lbs depending on the model).
But this is not perfect.
If you have pets:
- Choose pet-rated sensors
- Place them carefully (avoid stairs or furniture pets climb on)
- Test your system
Motion sensors sit inside the home, catching anything that slips through earlier layers.
How Families Use Motion Sensors (Without Constant False Alarms)
Motion sensors are not meant to be active while people are moving around the home.
Most systems use two simple modes:
Away Mode (Nobody Home)
- Door/window sensors ON
- Glass break sensors ON
- Motion sensors ON
If anything moves inside, the alarm triggers.
Stay Mode (Home / Sleeping)
- Door/window sensors ON
- Glass break sensors ON
- Motion sensors OFF (typically)
This allows:
- Kids walking around
- Getting up at night
- Normal movement
Without triggering the alarm.
More Advanced Setup (Optional)
Some families keep select motion sensors active at night in areas no one should be.
For example:
- Downstairs living room → ON
- Entry paths → ON
- Bedroom areas → OFF
This gives you:
- Freedom to move where you live
- Protection where you shouldn’t be
Simple Rule
- Home = perimeter armed
- Away = everything armed
If you want more security:
- Add motion sensors only in “no-traffic” zones at night
This will depend on your family situation and will likely change often and as your family grows.
Bottom Line
Motion sensors are your safety net.
You hope they never trigger—but if they do, they can be the difference between:
- An intruder moving freely
- And an alarm going off immediately