How to Wire Smoke Detectors in Parallel?


Wiring a smoke detector is integral in ensuring your safety. Besides, it is one of the regulations you need for law compliance. You can hire an electrician to help you with the proper setup of the smoke detectors. But the process of setting up is not complex, and you can do it yourself.

One important thing to consider is that you need to set up the smoke detectors in parallel. So if any of the alarms switches off by mistake, the fire alarm will sound in the entire house.

Process of wiring smoke detectors in parallel:

Here’s the process of wiring smoke detectors in parallel:

Determine the number of smoke alarms:

You’ll have to determine the number of smoke alarms that you’ll need for your house. 12-2 NM cables would also be required, so you need to find the right smoke alarms and wires before continuing anything further.

Cut the drywall:

You’ll have to cut the drywall at every point you need to install the fire alarm. Hold the box at the location where you need to set it up. Trace the outline with a pencil and cut the drywall.

Put the connection with 12-2 NM cable:

Put the 12-2 NM cable with the first fire alarm. However, wait for setting up the electrical connections. Continue the wire fishing to the second fire alarm, then continue to the third, and so on.

Now, Staring from the last fire alarm, put the wire through the knockout till you see the wire coming out of the box. Tighten the wire inside the box by adjusting the wing screws.

Setup the electrical connections:

Cut out the outer wires to reveal black, white, red, and bare wire. Use a ground screw to secure the bare wire. Use the wiring harness of your smoke alarm for the connection. Connect the back wire of the harness with the alarm’s black wire; connect the white and yellow wires in the same way.

Now, you should install the mounting bracket of the smoke alarm and pull the center access hole. Put the harness plug into the smoke alarm and twist the alarm so it gets into the bracket properly.

Move backward from the last alarm to the first one and continue the same procedure.

Once you reach the last smoke alarm, you’ll have two black, two ground, one yellow, and red wire available. Connect the same color wires with each other and the yellow one with the red.

Connect at the electrical panel:

Now you’ll have to connect your smoke alarms with the electrical panel. Once the connection is made, turn the breaker on. Check if the light of each fire alarm is on. Now test each alarm by pushing the “test” button. Press the Cancel button to dismiss the test. If everything is working, then you have your fire alarms connected in parallel properly.