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.
Grade D The mains supply to smoke and heat alarms should either be a single independent circuit from the dwelling's main distribution board or a separately electrically- protected regularly used local lighting circuit.
Smoke detectors do not have their own dedicated circuit breaker. Instead, they are typically connected to a general lighting circuit or a dedicated circuit in the electrical distribution board. Smoke detectors operate on low power, typically consuming around 50-100 milliamps.
The National Fire Alarm Code (NFPA 72) requires hard-wired, interconnected smoke alarms with battery back-up on every level of the home, outside each sleeping area, and inside each bedroom. Alarms must be wired together so that if one sounds, they all sound.
To be installed correctly, hardwired smoke detectors require more than just the common sense needed to install battery-operated smoke detectors. To ensure they function seamlessly and avoid potential dangers, these units need to be replaced and installed by a licensed electrician.
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.)
Some smoke alarms are provided with both primary power that is hardwired in from the home's electrical system and a secondary battery backup. The secondary battery backup can be either a battery that needs to be replaced at least yearly, or it can be a 10-year sealed battery that does not need to be replaced.
You can install a hardwired smoke detector yourself, but only if you have a good familiarity with home electrical work and an understanding of electrical circuits before attempting this project.
The maximum number of smoke alarms that should be interconnected per NFPA 72 standards is 12. Always make sure the smoke alarms you are interconnecting are compatible. In addition to the 12 smoke alarms in the series, you can connect up to 6 compatible devices like door closers, bells, or lights.
It must go to the PGM 2 terminal and not any other PGM terminal for 2-wire smoke detectors. You will then take the positive wire from your first smoke detector and wire it into the AUX+ terminal on the main board.
Smoke, Fire & Gas Detection FAQs
Yes, hard-wired mains powered alarms can be wired to the unswitched live feed of the nearest frequently used lighting circuit.
Fire alarm cable must have a voltage rating of at least 300V and (new with the 2017 NEC) a temperature rating of at least 60 DegrC [760.179(C)]. Type FPLP plenum cable must be listed as being suitable for use in a plenum space [760.179(D)]. Cables must be marked per Table760.
The same fuse or circuit breaker in the home powers all interconnected units. The total length of wire interconnecting the units should be less than 1000 feet (300 meters), and the maximum number of interconnected units on the same circuit is 18 total units, with 12 of those being smoke detectors.
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.
The electrical code does not require that hardwired smoke detectors need to be connected to a dedicated circuit, though there is nothing wrong with installing a new circuit for this purpose. More often, though, hardwired smoke detectors are installed by splicing into a general lighting circuit or outlet circuit.
You can replace the wiring harness with the power on, if you follow a couple of guidelines. One.. work with only one wire at a time. Two, don't let the black wire touch anything while you are splicing it to the new harness, and don't touch the uninsulated portion of the wire with your bare hands.
Every 10 years
Replace your smoke alarm. Some models last as little as 5 years. This includes battery operated and hard-wired alarms. All smoke alarms have an expiration date.
For new construction commencing August 14, 1992 only, the smoke alarm must be hardwired with a battery backup. For all other homes, the smoke alarm may be battery operated. (Cal. Health & Safety Code § 13113.7.)
Whether you choose to go with a hard-wired system or an interconnected system, your smoke detector installation should be completed by a qualified electrician. A professional will ensure that the job is done right the first time in accordance with state and local regulations and standards.
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.
Since no one can predict what type of fire might start in their home, the U.S. Fire Administration recommends that every home and place where people sleep have: Both ionization AND photoelectric smoke alarms, OR. Dual-sensor smoke alarms, which contain both ionization and photoelectric smoke sensors.
Because smoke rises, you should place alarms on the ceiling. If you cannot do this, place them high up on a wall according to manufacturer's instructions. Most importantly, read the installation instructions that come with the alarm.
According to the United States Department of Homeland Security, and the California Building Code, at least one smoke detector needs to be placed in each of the following areas of your home: On Every Floor Level. In Every Bedroom. In Every Hallway Outside of a Bedroom.
First, always remember the ceiling is always the best option and if available it should be used. Per the NFPA all detectors must be located within 4 to 12″ of the ceiling or in rooms with sloped ceilings it must be located on the tallest wall towards the peak.