How to Connect a Smoke Detector

Wiring a Single Smoke Detector

• 1

  Locate a receptacle to use as a power source.

• 2

  Make the cut in the ceiling for the new two-wire smoke detector.

• 3

  Cut an access hole above the receptacle at the point above the receptacle where the wall and ceiling meet to feed the cable across the ceiling.

• 4

  Cut the circuit power and remove the receptacle from its box.

• 5

  Run the two-wire NM cable to the detector. Feed fish tape through the access hole across the ceiling to the detector's hole. Attach the cable to the tape and pull it back toward you. Drop the cable down to the receptacle box.

• 6

  Install the detector's cut-in box. Open a knockout in box and feed the cable through it. Insert the cut-in box through the hole and tighten the wing fasteners.

• 7

  Mount the two-wire detector according to the manufacturer's instructions, connecting the black wire to the detector's black wire and the white wire to its white wire.

• 8

  Connect the wires at the power source with the black wire connected to the brass terminal and the white wire to the silver one. Restore power to the circuit and patch the hole in the drywall.

Wiring Parallel Smoke Detectors

• 9

  Locate a receptacle to use as a power source and plan the straightest path for the wires.

• 10

  Make the cuts in the ceiling for each smoke detector. Cut access holes for feeding the cables according to your wiring plan.

• 11

  Cut the power to the circuit and remove the source receptacle from its box.

• 12

  Run the cables for each detector. Run two-wire cable from the power source to the first detector and three-wire cable to each subsequent detector.

• 13

  Install the cut-in boxes. Feed the wires into the boxes before mounting them in the ceiling.

• 14

  Connect the detectors. At the first detector, connect the black wire from the power source to the detector's black wire and the black wire leading to the next detector. Connect the white wires in the same fashion. Connect the red wire leading to the next detector to the yellow wire on the first detector. Repeat for each detector in the circuit.

• 15

  Connect the black wire to the source receptacle's brass terminal and the white wire to its silver terminal. Restore power to the circuit and patch any holes in the drywall.