This project is continued from Part 2.
Smoke Alarm Installation
A second Kidde/Firex® Dual Sensor (Ionization and Photoelectric) AC powered hardwired smoke alarm will now be installed in the living area of the finished basement. The smoke alarm, NM-B 14/3 cable roll and old work electrical box are shown here:
Smoke Alarm Wiring Diagram
The NM 14/3 branch circuit for the new smoke alarm was connected to the octagonal ceiling box in Part 2. The NM 14/3 wire will now be strung along the floor joists to the main room in the finished basement to install the alarm in the suspended drywall ceiling. The wiring diagram for this work is illustrated below:
Smoke Alarm Ceiling Box Installation
After stringing the NM 14/3 cable along the floor joists and fastening it with cable staples every 4 or 5 feet, I wedged myself into the crawlspace above the finished basement and reached out as far as I could to position the electrical box on the suspended drywall ceiling above the basement living room. The smoke alarm must be at least 4 inches away from the walls and I’m at least 2 feet away here.
I positioned the ceiling box parallel to the metal stringers and traced the outline of the box on the drywall ceiling with an pen. The box outline is highlighted in red for better viewing. Note: Do not trace around the two “ears” on each end of the box.
Drywall Ceiling Electrical Box Installation
I cut along the box outline I traced on the ceiling with the Stanley FatMax® Jabsaw. The FaxMax made quick work of cutting the hole. When starting a cut, I find it best to work the pointed nose into the drywall to puncture through rather than pounding the saw in – you’ll have a cleaner starting cut with less tearing of the drywall paper face. My helper was on a ladder inside the room holding a plastic tub against the ceiling to catch the dust.
I slipped the old work electrical box in the hole to ensure it would fit when I mounted it from inside the room. It fit perfectly the first time.
I removed the old work electrical box and fed the NM 14/3 cable through the hole in the drywall ceiling for the smoke alarm.
View of the ceiling cutout and cable drop for the new hardwired smoke alarm from inside the finished basement.
Smoke Alarm Ceiling Box Mount
The NM 14/3 cable is fed through the old work electrical box and the box is inserted in the ceiling hole. This style of old work box has two “wings” that extend and grab the backside of the drywall when the two corner screws are tightened. Be careful not to over tighten the mounting screws or the wings can crush the drywall. Stop when the box is snug. Notice that I’ve got the DeWALT cordless drill/driver set on a low torque setting.
Smoke Alarm Ceiling Box Wiring
The NM-B 14/3 wires are cut to about 6 inches long and stripped as shown. Only 1/2 inch of insulation is stripped from the ends to match the exposed wire of the Kidde PI2010 AC Quick Connect Harness. Notice the copper ground wire is wrapped out of the way since it’s not used and there’s nothing for it to connect to on this terminating circuit.
I’ve set two flat head 8/32 thread by 3/4″ long screws in the box ends to secure the smoke alarm trim plate. The old work electrical box doesn’t include these screws, so you’ll have to provide your own.
The Kidde PI2010 AC Quick Connect Harness is fastened to the NM 14/3 wires with wire nuts.
Almost done! The trim plate is fastened to the ceiling electrical box with the two screws, the wiring harness is plugged into the smoke and the smoke alarm ratcheted onto the trim plate.
Remember to pull the yellow ribbon from smoke alarm to activate the battery backup!
Kidde PI2010 Smoke Alarm Testing
I turned on the circuit breaker to restore the AC power to the smoke alarm circuit and walked through the house to verify the green AC power LED is illuminated on all the smoke alarms. Yes! Steady green lights on the units. I also watched each smoke alarm to see the red LED flash about once a minute indicating the smoke alarm is operating properly in standby mode.
With my helper on the 2nd floor, I visited every smoke alarm in the house and pressed the “Test” button on each unit for at least 5 seconds. The alarm sounded followed by all the other alarms going off as it should for an interconnected system. Very loud and annoying, but working as advertised!
If you click and zoom in on this photo, the green LED is illuminated on the smoke alarm in the finished basement:
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