Article Summary:
Nest Protect has eight sensors that allow it to know what’s happening in a room and detect dangerous levels of smoke and carbon monoxide. In addition to detecting potential threats, Nest Protect has four sensors that detect movement so it can light up your path at night.

Nest Protect uses information from its sensors to detect potential threats in your home:

• A photoelectric smoke sensor uses light to detect smoke particles in the air.
   
• A carbon monoxide sensor detects carbon monoxide, an odorless and colorless gas. When combined with heat, carbon monoxide often indicates there is a fire present.
  Learn more about carbon monoxide
   
• A heat sensor allows Nest Protect to detect sudden rises in temperature.

In addition to protecting you with three safety sensors, Nest Protect includes a humidity sensor, as well as activity sensors that light your path at night.

• Two ultrasonic sensors detect movement.
• One occupancy sensor detects when you are under Nest Protect at night to turn on Pathlight.
  Learn more about Pathlight
   
  For consumers who have a Nest Learning Thermostat, the occupancy sensor improves the Auto-Away algorithms.
  Learn more about Auto-Away
   
• An ambient light sensor lets Nest Protect know when it’s dark or when the lights are off inside your home. This sensor is used for Nightly Promise and Pathlight.
  • When you turn off your lights at night, Nest Protect will briefly glow green, giving you the Nightly Promise that its sensors and batteries are working correctly.
    Learn more about Nightly Promise
     
  • As you pass under Nest Protect in the dark, Pathlight will light your way.
    Learn more about Pathlight