Smokies and AFCI's

At new construction site’s, why are some smoke detectors protected by AFCI’s and others not?

They are only protected by AFCI’s in bedrooms.

I inspected a townhouse today about 1,100 sq feet in size built in 1972. I could not locate the main service panel. In the distribution panel there was a 50amp main service breaker. Would this be sufficient


Since they are required to be interconnected and on the same circuit this would make them all on AFCI’s. Some areas may not have adopted the AFCI requirement which began in 2002. And if building permits were pulled before the date that the requirement was adopted by the AHJ, the requirement would not be enforced. Since many areas are 3 or more years behind on code adoption, you may be looking at homes where the permits were pulled in 04 or 05, before your area adopted the code.

I have a question now. Why would anyone install smoke detectors on a circuit that is AFCI protected?

EX: 3 bedroom colonial with a basement and a main floor office (could be used as a 4th bedroom).

– 2nd floor –
4 smoke detectors: 1 in each bedroom =3 + 1 in hallway
– 1st floor –
3 smoke detectors: 1 in office (4th bedroom) + 1 in main living space + 1 in kitchen/dinning area
– Basement –
1 smoke detector: 1 near base of staircase

Now if the AFCI tripped for some reason (should only happen if a receptacle is on the same circuit) the whole systen should run on the battery back-up. Why would anyone put a safety system in a position where it could be deemed useless because your teenager plugged something into a receptacle and tripped the AFCI three months ago and never told anyone. They just didn’t use the receptacle that don’t work in their bedroom. Now a fire happens and all the batteries have died from their age because no one has changed them in the last three years. By the way that same teenager started the fire smoking in their bedroom and hiding it from you.

Isn’t the smoke alarm system required to be on a designated circuit? If not it should be… What is the use of a safety system that can be accidentally disabled without anyone knowing?

In lamans terms what does the most up to date code say about smoke alarms??

You have to take that up with NFPA. In 2005 all bedroom circuits have to be AFCI, including the smokes. In 2008 it will be all 120v 15 and 20a circuits in a dwelling, no matter what is on them


Firstly, you have forgotten one on the 2nd floor…if the AHJ determines that the hall smoke will not cover the open space of the actual floor then you would have to add one their.

Secondly, Maybe Greg can jump in here on this but I have done MANY homes and I do not put a smoke in the Kitchen or Dining Room…

I have never been turned down for not having a smoke in the kitchen or dining room…

As for the circuit, as stated before we install a AFCI circuit just for the smokes and then actually hit the attic light and receptacle on our Smoke Circuit…I like having the attic items on the AFCI for one…but thats just me.

Ok…on your question…sticking something into a receptacle that is AFCI is not going to trip it…an AFCI has a distinct purpose…if it trips the smokes will let you know in most cases…most I know blink or buzz when on battery backup…but maybe not all…I have never found this to be a large issue.

If someone plugs something in that OVERLOADS the circuit and it trips the breaker itself…which remember it has that function as well…over an above the AFCI protection…most with a BRAIN would go and reset it like any breaker…

AFCI’s just dont trip to trip…they are MUCH better these days and it is more of a MYTH than fact at this point in the game…

Really is nothing to be concerned about really…

Sorry Paul, I’ll have to disagree here.
IMO they still have not perfected the technology, yet they are shoving them deeper down our throats.

ALL 15 and 20a 125v circuits??? That is a crock!!!

Thank you for you reply. I like how you put AFCI protected smokes separate from room AFCI’s. That was my point, not to be connected to the same circuit as the rooms.

I ment if something was to be plugged in that caused an arc-fault.

Remember I am talking about the common teenager, you know those people that where pajamas and shower shoes out in public as street clothes. My teen can’t be bothered to press the reset on the bathroom GFCI when he accidentally hits the test button when plugging in his shaver.

Oh, thanks for the catch on the 2nd floor / Kitchen smokes… I knew I was missing one so I threw in the kitchen one… My point is that in my opinion smokes should be on a separate circuit from the other common used circuits in the house. I can except the attic being on the same circuit because the attic is not normally a commonly used circuit. I am just surprised that smokes are not required to be separate from common use house circuits like the bedroom circuits.

Thanks Paul for your knowledge.

IMO the smokes should be on the same circuit as the bedroom circuit, that way if the breaker does trip you will know because your teenager’s stereo won’t work and they will tell you. If the smokes are on a dedicated circuit and the batteries are dead, what’s to let you know that the smokes aren’t working?

That is my point… if they are on their own circuit there would be nothing being plugged in to cause an Arc-Fault that would cause the AFCI to trip.

Of course there is always the random unusual trip such as lightning, etc. but not likely. If that happened most likely other things will be having problems also.

Personally I am not sure why NFPA doesn’t just stop screwing around with this fire alarm business and make dwelling smoke alarms a subset of article 760. It is becoming complex enough now that it is not that big a step to just require a central controller and power supply, lose all of those 9v batteries and get it off the general lighting circuits altogether.
They keep trying to increase performance and still keep using Kmart hardware. Why not just install a real fire alarm system

At $40.00 apiece a dedicated AFCI for the smokes is a luxury most electrical contractor can’t afford. Residential wiring is very cut throat and one must make concessions.
If the homeowner isn’t concerned enough with his own safety to replace the batteries in his smokes, then why should I be concerned enough to spend the extra money to try to idiot proof his house?

Smokes should be on the sumppump circuit so when the sump fails it can help put the fire out.:mrgreen:


Well we can AGREE to disagree…I have installed many of them and never had the issues…only time I see issues is when a freakin NEWBIE electrician tries to run a multiwire circuit for bedrooms and it shares a neutral…then the AFCI can have issues…but for the most part…They have been more than stable for me and my experience.

It is ok to disagree…:)…no problem…but it wont change MY mind…but yes I agree they are getting DEEPER down our throats and will only get worse…thats for sure…

Yeah…but I have had a LONG week and for some reason it it taking 7 days for me and a helper to wire a freakin 3,000 sq ft house so I am a little against PAJAMA people right now…lol…no actually…I know where you are going but to be honest I do not see AFCI’s tripping randomly enough to make me worry about them…ALSO until like GREG said in his post…the NEC starts to either GET on the POT or GET OFF the POT…their will be confussion…

I have one local inspector who wants a smoke at the VERY top of a cathedral ceiling…like 2 feet…now all the material on them say do not do it becuse it develops a VOID and the alarm will not go off…read the BRK manual on installing them…yet he mandates it…local AHJ’s run random on them…I agree with GREG…