Installing smoke and carbon monoxide detectors is one of the most important steps you can take to protect your home and family. These devices give early warnings during fires or dangerous gas leaks, giving you time to act quickly.
In the video above, Ask This Old House master electrician Scott Caron shares the proper installation techniques for a comprehensive, hardwired detection system. While we advise hiring a licensed electrician for the job, it’s still helpful for homeowners to understand the process.
Understanding Smoke and Carbon Monoxide Detectors
Modern safety codes require homes to have both smoke and carbon monoxide detectors. These devices work together to protect against two distinct threats: fire and toxic gas poisoning.
Carbon Monoxide Detectors
Carbon monoxide (CO) is an odorless, colorless gas that comes from burning fossil fuels. CO detectors monitor the air for this deadly gas and alert you before the levels become harmful.
Carbon monoxide poisoning is a silent killer. If your home has gas appliances or an attached garage, CO detectors are especially important.
Smoke Detectors
Smoke detectors sense smoke particles in the air and sound an alarm if they detect fire. They use either photoelectric or ionization technology. Some models use both technologies for improved detection.
Combination Devices
Many modern detectors combine both smoke and carbon monoxide detection in a single unit. They cut down on the number of devices you need to install and maintain.
Detector Placement Guidelines
Follow these guidelines to achieve the best possible coverage in your home:
- Keep detectors away from windows, doors, or vents to avoid airflow disruptions.
- Install carbon monoxide detectors on every level of your home and within 10 feet of each bedroom.
- Keep detectors at least 10 feet away from cooking appliances to prevent false alarms.
- Mount detectors on the ceiling or high on walls since smoke rises.
- Place smoke detectors inside and outside each sleeping area.
You might install specialized detectors in areas like the garage or kitchen, where the risk is higher. You’ll find more about these options below.
Types of Detectors
Choosing the right detector depends on your home’s needs. Here are your options:
- Battery-powered detectors: These stand-alone units are easy to install and don’t require any wiring. They rely solely on battery power and need regular battery replacements. Check the batteries regularly to prevent any lapses in protection.
- Hardwired detectors: Hardwired detectors connect directly to your home’s electrical system. They typically include a battery backup for continued protection during power outages. These detectors are stable, and you’ll have to check them less frequently than battery-powered units.
- Interconnected systems: Interconnected detectors communicate with each other, so all alarms in the house will sound when one device detects a threat. This feature is great in larger homes where you might otherwise miss a distant alarm.
- Smart detectors: These advanced devices can send alerts to your smartphone and integrate with home automation systems for increased safety and convenience. By providing real-time updates, smart detectors make sure you are always aware of the status of your home, even when you are away. They can also provide diagnostic information, helping identify issues with the detectors more quickly.
- Wireless options: For homes where running new wiring is challenging, wireless interconnected detectors may be a solid option. These devices communicate via radio frequency, eliminating the need for physical wiring between units. Wireless systems offer flexible installation options and are particularly suitable for older homes with structural limitations.
Tools and Materials Needed To Install a Detector
Before beginning the installation process, gather the following tools and materials:
- Drill with various bits
- Dust mask and safety glasses
- Hole saw (4-inch diameter)
- Ladder
- Nonmetallic electrical cable
- Old work electrical boxes
- Screwdrivers
- Smoke and carbon monoxide detectors
- Wire connectors
- Wire strippers
- Voltage tester
Smoke and Carbon Monoxide Detector Installation Process
Hardwiring smoke and carbon monoxide detectors is best left to the pros. Here are Caron’s steps for a successful installation:
- Turn off power to the circuit you’ll be working on at the main electrical panel.
- Mark the locations for your detectors on the ceiling, following the placement guidelines outlined earlier.
- Use a stud finder to locate ceiling joists and check that you’re not drilling into any obstructions.
- Drill small pilot holes at each marked location and check the attic for any potential obstacles.
- Use a 4-inch hole saw to cut openings for the electrical boxes at each detector location.
- Run nonmetallic electrical cable from an existing power source to each detector location, following your local electrical codes.
- Install old work electrical boxes in the ceiling openings, securing them tightly.
- Strip the ends of the electrical cables and connect them to the detector’s wiring harness: black to black (hot), white to white (neutral), and red to orange (interconnect).
- Carefully tuck the wires into the electrical box and attach the detector’s mounting plate.
- Connect the detector to the mounting plate by twisting it into place.
- Repeat the process for each detector location in your home.
Check that all connections are secure and double-check for loose wires that might cause issues later on. The installation should adhere strictly to local codes and regulations for the best possible safety and compliance.
Special Considerations for Smoke and Carbon Monoxide Detectors
When installing smoke and carbon monoxide detectors, keep these additional factors in mind:
- Interconnectivity: When you’re installing multiple detectors in an interconnected system, be sure to connect the interconnect wires (usually red or orange) between all units. This feature provides comprehensive coverage and immediate alerts, improving response time in emergencies.
- Power source requirements: Modern building codes often require detectors to have two power sources: hardwired electrical connection and battery backup. This leads to continued protection during power outages. A reliable power source is essential for the continuous operation of these safety devices, so be sure to double-check your local codes.
- Redundancy and layered protection: For added security, think about layering different types of detectors to cover various threats more effectively. Besides the centrally located detectors, for example, you might place smaller and more sensitive units in areas like the furnace room or garage where risks are higher.