Although the electrical code doesn't require that hardwired smoke detectors be connected to their own dedicated circuit, it doesn't hurt to install a new circuit to power these detectors. Hardwired detectors are usually installed by splicing into a general lighting circuit or outlet circuit.
The interconnected smoke detectors need to be on an dedicated 15amp arc fault breaker. This circuit shall serve nothing but the smoke detectors. The wire from the breaker to the first detector will be 14-2 with ground. Then from one detector to the other - you will use 14-3 with ground.
Per NFPA 72: National Fire Alarm and Signaling Code, 2010 Edition – Chapter 10 Fundamentals– fire alarm systems, to include fire alarm control panels, fire alarm audio/visual notification appliances (NAC) power supplies, and fire alarm communicators must be installed on a dedicated power circuit.
All smoke detectors required by this chapter shall be mounted on a ceiling or wall; provided, that if wall-mounted, they shall be within twelve inches but not closer than six inches of the ceiling. Further, they shall be located in any corridor or interior area giving access to rooms used for sleeping purposes.
A maximum of 18 compatible units may be interconnected (Maximum of 12 Smoke Alarms). The same fuse or circuit breaker must power all interconnected units. The total length of wire interconnecting the units should be less than 1000 feet (300 meters).
Generally, there is no requirement to have the smoke detector connected to a specific circuit. The circuit to which the smoke detector is connected depends on the technician handling wiring. However, in more cases than not, residential smoke detectors are installed by splitting the general lighting circuit.
For many years NFPA 72, National Fire Alarm and Signaling Code, has required as a minimum that smoke alarms be installed inside every sleep room (even for existing homes) in addition to requiring them outside each sleeping area and on every level of the home. (Additional smoke alarms are required for larger homes.)
Article 760 (Fire Alarm Systems) of NFPA 70 (National Electrical Code) governs fire alarm system wiring and equipment, including all circuits controlled and powered by the fire alarm.
The round or octagonal box houses lightweight fixtures or safety devices in the ceiling. These are used for lights or smoke and carbon monoxide alarms. A ceiling box is for heavier fixtures, such as ceiling fans or chandeliers. Be sure to choose a ceiling box that is made to support extra weight.
A fire alarm breaker is a circuit breaker that protects the fire alarm control panel from too much electrical current and is designed to trip when there's an overload or short circuit, which cuts off the flow of electricity and prevents a fire.
Can I install a hardwired smoke detector myself? While it is technically possible, it is not recommended. Working with your home's electrical system can be dangerous and complex, best left to a qualified electrician.
of the CE Code (2018), Rule 32-110 will permit a smoke alarm(s)—or a smoke alarm that includes a carbon monoxide alarm—to be connected to a GFCI/AFCI-protected circuit provided it has a battery-powered secondary supply.
Smoke alarms have been required to be on an AFCI protected circuit for at least the past 4 code cycles, maybe more depending on their location. Nuisance tripping should be a non-issue. If they do trip that's what the battery backup is for.
Common Causes of Beeping in Hard-Wired Smoke Detectors
Low battery: Even hard-wired smoke alarms have backup batteries that need replacing periodically. A low battery can cause that annoying beeping sound. Dust buildup: Dust and debris inside the smoke detector can trigger false alarms.
According to the NFPA, smoke alarms should be placed in every bedroom, outside each sleeping area and on every level of your home. In addition, industry experts recommend having both photoelectric and ionization alarms for optimal protection against flaming and smoldering fires.
Smoke alarms are to be installed in all residential dwellings (single family homes, multi-family homes, hotels, rental properties, dormitories, etc.). Smoke alarms in newly constructed or renovated dwellings are required to be hardwired with a battery back-up, interconnected, and UL-listed. NFPA 720 (2015 ed.).
System smoke detectors in accordance with NFPA 72®, National Fire Alarm Code®, and arranged to function in the same manner as single-station or multiple-station smoke alarms shall be permitted in lieu of smoke alarms.
If you have a home security system or smart devices that you use for home automation, smart smoke and carbon monoxide detectors make a great addition. Syncing your smart detectors with your existing smart home devices allows for easy access to all of your systems with one app.
Never place them any closer than three feet from an air register that might re-circulate smoke. Don't place them near doorways or windows where drafts could impair the detector operation. Don't place them on an uninsulated exterior wall or ceiling. Temperature extremes can affect the batteries.
A new standard for smoke alarms, which went into effect on July 30, requires smoke detectors to be more sensitive to all types of fire and to have fewer nuisance alarms from cooking. NIST research in a kitchen fire laboratory shows that these smoke alarms still produce nuisance alarms during cooking.
- Within 3 feet of an air supply vent (supply or air flow) - Within 1 foot of a light fixture. - Within the “dead air space” where the wall meets the ceiling (ceiling smoke alarms must be at least 4” from the wall, wall mounted smoke alarms must be at least 4” and no more than 12” from the ceiling.