Smoke detectors and fire alarms are an important part of your home’s safety plan. Fires and smoke inhalation injures and kills many people each year. You can avoid these tragedies by having smoke detectors installed in your home.
Hardwired smoke detectors are wired in a way that if one of them detects smoke or fire, the others will go off as well. These smoke detectors also feature battery backup. They run on 125-volt power until the power goes out. Then, the battery kicks in and the smoke detectors keep protecting you.
To install smoke detectors in your home, you need to determine the appropriate location and cut the boxes in the upper walls or ceilings. If you’re going to install smoke detectors in the walls, mount them around 12” below the ceiling. Use a stud finder to locate the studs in the walls, so the boxes won’t end up on studs. If you’re installing smoke detectors in the ceiling, locate the ceiling joists and cut next to them. Mark the locations for the boxes with a pencil and use a drywall saw to cut the holes in the drywall.
The next thing to do is install electrical wires from the electrical panel or fuse box to the smoke detectors. Run a 12 – 2 NMB with ground wire to the first box, which will give you a hot, neutral and ground wire. Make “hot wire” on this piece of wire at the box. Then, run a 12 – 3 NMB wire with ground from the first box to the second box. For all the boxes, run a 12 – 3 NMB with ground wire to each of them. When you’re finished, no box should have more than two wires.
Next, go to the first box, connect the two black wires together and add the black wire from the smoke detector connection. After that, tie all the white wires together. Tie the bare copper ground wires together and run a pigtail to bond it to the box. Connect the red wire to the interconnect wire from the smoke detectors. The interconnect wire is usually yellow and marked. Each connection with a wire nut should be big enough to cover all exposed wires.
Place the smoke detectors mounting brackets over the box openings, aligning the two screw holes. Make sure that the wire connections are fed through the center holes of the brackets. Install the appropriate sized screws and tighten the mounting brackets in place.
On the backs of the smoke detectors there are there are three-pronged connections. This is where the plug that you just wired will attach to the smoke detectors. It is configured so that you can only plug it in one way.
Next, open the battery covers on the backs of the smoke detectors. The positive and the negative are marked both on the batteries and the smoke detectors. Install the batteries and replace the covers.
Take the smoke detectors in your hands and align the slots on the backs with the notches on the base. Twist the smoke detectors until they lock into place. Both sides of each should be snug and secure.
Next, strip the end of the non-metallic sheathed wire and connect the ground wire to the ground buss. The white wire should be connected to the neutral buss. Make sure the breaker is in the OFF position and connect the black wire to a 20-amp breaker or fuse. Mark the panel schedule with the placement location of the breaker you connected to. If there isn’t a spare breaker, you can either add a breaker or add it to an existing circuit that doesn’t have much connected to it.
Replace the panel cover and turn the circuit on that controls the smoke detectors. Never stand directly in front of a panel, when turning on and off breakers. Push the test button on the smoke detectors. You need to hold the buttons in for a few seconds before they sound an alarm. With the interconnection wire, all the smoke detectors should be sounding, but make sure you have someone to walk around all of the smoke detectors and check if they are also going off. Release the button and it should go silent again.