Because hardwired alarms run on a 120-volt circuit and connect to each other through an extra wire, the work belongs to a licensed electrician. You can be connected with one by calling.
What a Hardwired Alarm System Includes
Each hardwired alarm mounts on a ceiling or wall box and gets steady power from a household circuit, with a backup battery that keeps it working during an outage. A third conductor, the interconnect wire, links the alarms so one alarm triggers every other one. Where running new cable through finished walls is impractical, some alarms use a wireless interconnect that works with the hardwired units.
Current code generally calls for an alarm in each bedroom, outside each sleeping area, and on every level including basements. Alarms come with photoelectric sensing, ionization sensing, or both, and combination smoke and CO units are common where carbon monoxide protection is also needed.
Times to Add or Replace Smoke Alarms
- The home relies only on separate battery alarms that do not talk to each other
- Existing hardwired alarms are ten or more years past their manufacture date
- You are finishing a basement, adding a bedroom or remodeling
- A home inspection flagged missing or outdated alarms
- Alarms chirp constantly even after the battery is changed
- You want alarms heard in bedrooms when fire starts elsewhere
Clues Your Current Alarms Are Falling Short
- Bedrooms with no alarm inside them
- No alarm at all in the basement or on an upper floor
- Alarms that go off every time someone cooks or showers
- Pressing TEST on one alarm sets off only that one
What Installation Involves
The electrician plans alarm locations first, keeping them away from kitchens, bathroom doors, supply vents and ceiling fans that cause nuisance alarms or blow smoke away. Cable is fished through attics and walls to each location, with the interconnect running between them. When replacing old units, the electrician checks that the new alarms are compatible with each other, since interconnect wiring generally only works within one manufacturer's line. Every alarm is tested as a group before the job is done.
- Required locations for bedrooms, hallways and each level
- Distance from kitchens, baths, vents and fans
- Interconnect compatibility between alarms
- The circuit feeding the alarms and any AFCI requirement
- Battery backup and manufacture dates
- A full system test from each alarm
Safety first. Test alarms monthly with the button, and replace any alarm ten years after its manufacture date, which is printed on the back. Never pull a battery or remove an alarm to stop nuisance alarms; have it relocated instead. If an alarm sounds and you see or smell smoke, get everyone out, stay out and call 911 from outside.
How it usually works
Call about your alarms
Describe the layout of the house and what alarms it has now, and you'll be connected with a local electrician.
Placement plan
The electrician walks the home and marks where each alarm should go under current code.
Wiring and mounting
Power and interconnect cable are run and the alarms are installed with backup batteries.
System test
Each alarm is tested to confirm every unit in the house sounds together.
For Birmingham-area homes
Plenty of Birmingham homes from the early and mid 1900s, in neighborhoods from West End to Crestwood, were built long before smoke alarms existed, and many still rely on a couple of battery units in hallways. Two-story houses and homes on hillside lots with finished lower levels make interconnection especially important, since an alarm on one floor can be hard to hear on another. Adding alarms is often part of a larger project like an electrical remodel, and it pairs naturally with carbon monoxide alarms in homes with gas appliances.
Related electrical problems
Noticing one of these? Each guide explains likely causes and what's safe to check before you call about smoke detector installation.