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Install or Replace Smoke / CO Detectors

beginner
Smoke and carbon monoxide detector being twisted onto its ceiling mounting plate
The detector twists onto a base plate screwed to the ceiling.
Safety first

Turn off the breaker and verify power is off before working. If you are not comfortable, hire a licensed electrician.

Step-by-step
1

Turn off the breaker for hardwired units.

Non-contact voltage tester held against an outlet slot to check for power
Touch a non-contact tester to the outlet or wires. No light or beep means the power is off.
2

Remove the old detector from its base and disconnect the pigtail.

3

Match the new wiring: black hot, white neutral, red/orange interconnect.

Wires joined with wire nuts showing black, white, and interconnect conductors
Black to black, white to white, and the red (or orange) wire links the alarms together.
4

Install the new base and connect the pigtail.

5

Mount the detector and press the test button after restoring power.

Pro tip for you

Replace detectors every 10 years and test them monthly.

Tools
  • screwdriver
  • drill (for new mount)
Materials
  • smoke/CO detector
  • mounting hardware