Residential Smoke Alarms

J

Jimmy7

Senior Member
Location
Boston, MA
Occupation
Electrician
When wiring a new home do you put the smoke detectors on their own circuit, or do you put them on with a lighting circuit? I know some people put them on with a lighting circuit so the homeowners won’t turn the circuit breaker off and keep it off. Is there a code anywhere on this?
 
Neither the NEC nor IRC requires smoke alarms to be on their own circuit. I used to put them on the unfinished basement lighting circuit.
I would believe if the HO turned the circuit off, the alarms would chirp.

Ron
 
rc/retired said:
Neither the NEC nor IRC requires smoke alarms to be on their own circuit. I used to put them on the unfinished basement lighting circuit.
I would believe if the HO turned the circuit off, the alarms would chirp.

Ron
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If the circuit is turned off the 120 smoke alarms will only chirp once the battery backup is dying and could leave them without interconnected life safety devices for an undetermined length of time especially if they don’t frequent the unfinished basement .
I’m not saying your way is incorrect at all because the nec doesn’t require any specific circuit to supply 120 volt interconnected smoke alarms . But I always try to feed them from from a lighting circuit that will instantly notify the homeowner if turned off like kitchen/dining lights or master bed circuit
 
Jaybone812 said:
If the circuit is turned off the 120 smoke alarms will only chirp once the battery backup is dying and could leave them without interconnected life safety devices for an undetermined length of time especially if they don’t frequent the unfinished basement .
I’m not saying your way is incorrect at all because the nec doesn’t require any specific circuit to supply 120 volt interconnected smoke alarms . But I always try to feed them from from a lighting circuit that will instantly notify the homeowner if turned off like kitchen/dining lights or master bed circuit
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Some will chirp ever so often if the power to them is off. Will chirp more often if the battery is dying.
 
infinity said:
When circuit breakers were $5 we used to always use a separate circuit but given the cost of an extra AFCI breaker it just gets connected to any local general purpose circuit.
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If you have a individual fire alarm circuit for just for the smokies I don't think they are required to be on a AFCI.
 
Little Bill said:
Some will chirp ever so often if the power to them is off. Will chirp more often if the battery is dying.
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Yea now that I think about it devices with replaceable batteries will chirp here and there if disconnected from their power source, but if you install devices with a 10 yr sealed battery they’ll run on battery for quite some time without making a noise . But like I said how they are fed is up to who’s doing the work and their preference code just requires them to be interconnected
 
Jaybone812 said:
Yea now that I think about it devices with replaceable batteries will chirp here and there if disconnected from their power source, but if you install devices with a 10 yr sealed battery they’ll run on battery for quite some time without making a noise . But like I said how they are fed is up to who’s doing the work and their preference code just requires them to be interconnected
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One of the last houses that I wired had 20' ceilings in the great room. The balcony for the upstairs was open to the great room. When I was trimming out the house, and installed all the smokes, I would turn off circuits if I needed to work on the circuit. I discovered through the HO that the smokes were chirping. I mentioned the open balcony because the upstairs smokes would echo in the great room because there was no furniture, or floor coverings, to absorb sound. The chirping was almost deafening due to the echoing. I made sure to turn the circuit back on that the smokes were connected to when I was finished working on it, or leaving for the day.
 
Little Bill said:
One of the last houses that I wired had 20' ceilings in the great room. The balcony for the upstairs was open to the great room. When I was trimming out the house, and installed all the smokes, I would turn off circuits if I needed to work on the circuit. I discovered through the HO that the smokes were chirping. I mentioned the open balcony because the upstairs smokes would echo in the great room because there was no furniture, or floor coverings, to absorb sound. The chirping was almost deafening due to the echoing. I made sure to turn the circuit back on that the smokes were connected to when I was finished working on it, or leaving for the day.
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That sounds like BRK photoelectric smokes with replaceable batteries lol
 
Little Bill said:
One of the last houses that I wired had 20' ceilings in the great room. The balcony for the upstairs was open to the great room. When I was trimming out the house, and installed all the smokes, I would turn off circuits if I needed to work on the circuit. I discovered through the HO that the smokes were chirping. I mentioned the open balcony because the upstairs smokes would echo in the great room because there was no furniture, or floor coverings, to absorb sound. The chirping was almost deafening due to the echoing. I made sure to turn the circuit back on that the smokes were connected to when I was finished working on it, or leaving for the day.
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But were they installed before connected to power , I’ve found that installed prior to being connected to a 120 volt source even if the tab is left in place in the battery compartment sometimes that tab gets shifted slightly off the terminal and the device will be using rhe battery without anybody knowing they are , but I’ve found 120 volt smoke alarms are fickle beasts and they’ll sound a nuisance alarm because they feel like it with no rhyme or reason as to why so I definitely believe you lol
 
Jaybone812 said:
But were they installed before connected to power , I’ve found that installed prior to being connected to a 120 volt source even if the tab is left in place in the battery compartment sometimes that tab gets shifted slightly off the terminal and the device will be using rhe battery without anybody knowing they are , but I’ve found 120 volt smoke alarms are fickle beasts and they’ll sound a nuisance alarm because they feel like it with no rhyme or reason as to why so I definitely believe you lol
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No, the power was on. I only remove the tabs after the green light was on showing AC power. Even if the tab was shifted before AC power, the battery would run a long time before it would be depleted. The chirping with no power is to let you know the power is off.
 
infinity said:
The AFCI protection requirement is for any outlet in the locations listed in 210.12. I don't see an exception for smoke alarms. There is an exception for FA systems power.
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All I know is I was completely unaware of it until we had a job with a regular 15A breaker on a circuit that supplied smoke detectors in a dwelling unit, and the inspector asked that it have red identification, per 760.41(B), his interpretation was that as soon as you interconnect smoke alarms you have met the minimim definition of a system, and since 760 prevails over 210 the exception does not even come into play (Non-Power limited fire alarm circuit)
 
tortuga said:
All I know is I was completely unaware of it until we had a job with a regular 15A breaker on a circuit that supplied smoke detectors in a dwelling unit, and the inspector asked that it have red identification, per 760.41(B), his interpretation was that as soon as you interconnect smoke alarms you have met the minimim definition of a system, and since 760 prevails over 210 the exception does not even come into play (Non-Power limited fire alarm circuit)
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I’ve never heard of any ahj or representative of classify 120 volt interconnected life safety devices as part of a fire alarm system , and the connection to the device is a outlet so current nec rules specifically 210.12(b) is going to require afci protection . And imo the only way he could omit the requirement for afci protection, and I feel it’s a stretch at best is if the smokes were supplied by a individual branch circuit and he considered 210.12(b) exception 1 as applicable to the installation


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tortuga said:
All I know is I was completely unaware of it until we had a job with a regular 15A breaker on a circuit that supplied smoke detectors in a dwelling unit, and the inspector asked that it have red identification, per 760.41(B), his interpretation was that as soon as you interconnect smoke alarms you have met the minimim definition of a system, and since 760 prevails over 210 the exception does not even come into play (Non-Power limited fire alarm circuit)
Click to expand...

Do you agree that is the intent ??


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UL would never list a smoke alarms that chirped when loosing the primary power source. Homeowners would remove the alarms every time the power went off leaving no protection. They only chirp on low or no battery.
 
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