Hello. We have an outside post light that is on an automatic photoelectric switch. Today I learned this light is wired on the same circuit as our smoke detectors. We have a new build home and all the smoke detectors are interconnected on AC power. Is this illegal to have the light on the same circuit as the smoke detectors? We live in the state of New York if that makes a difference in the laws/codes.

Thanks
ptwilliamsons2

 

It is very common for smoke detectors to be wired into a lighting circuit. They should also be on an Arc Fault breaker.
One of the reasons for smoke alarms being on a light circuit is to help the homeowner know if the circuit is tripped. If the light does not work then the smoke alarms proably do not either. You may find that there are some other lights on the circuit also such as the foyer light or porch light.

B

 

Only thing NFPA 72 states is that they must be 120v powered with battery backup. No requirement for dedicated circuit that I have found.

It's usually recommended to be dedicated so you don't leave the breaker off while working on another fixture.

 

Code allows it either way. I strongly prefer that the smoke detectors be on the same circuit as a frequently used light.

 

Worried--check w/ your bldg. inspector.
Today we purchased 2 smoke detectors ( for clg. fixture )
They screw into light socket & bulb screws into smoke detector ( UL label ).......................

 

John,

You do bring up a valid point there. Have them on a frequently used light......that way if the light don't work, you will check the breaker. If it's dedicated, you will have no idea the breaker tripped....hmmmm

 

No... You will. They all beep at you in unison to signify they are running on battery power. They'll keep doing that every X amount of minutes until power is restored (atleast the ones I've worked with). They even do the same thing if only one battery is dead. They'll all start beeping at you.

Actually, I'll have to double check that. I know they indicate weak or dead batteries and I thought they did it on no AC as well but now I'm not sure. Don't have interconnected smokes at home so I can't test.

I always have smokes on a dedicated circuit regardless. With life saving equipment, it really only makes sense to IMO... Same reason you don't put hospital equipment on a GFCI. Not if you want to live anyway....

 

I am not sure why you would want them on an arc fault breaker. I would want power supplied to the smoke detectors even if the house were burning down due to an arc fault. Same as with other fire and life safety equipment: never on GFCI or AFCI. I especially want that stuff powered if there is any kind of problem threatening the occupants or structure. Fire pump circuits for example are sized for locked rotor current, so if the pump does fail, it won't be just because the breaker tripped.

 

Ok. Well, if there is no code prohibiting our current wiring I guess I'll just let it go as I really don't want to take on a rewiring project right now. I see the benefit in having a frequently used light tied into the same circuit. I just figured an outside light was bad as it had a greater possibility of tripping the breaker and disabling the smoke detectors. Thanks for everyones replies.

 

It doesn't matter if you want the smoke alarms on a AFCI circuit or not. Unless over-ridden by local adoptions the NEC requires the smoke alarms to be on a AFCI circuit since you have them in bedrooms and by definition smoke alarms are an outlet and all outlets in bedrooms need AFCI.

Even if the AFCI were to trip there is still the backup battery to provide protection.

With the adoption of the 2008 NEC all the circuits will be AFCI, with the exception of the GFI circuits for the kitchen and baths.

 

Understood. I know this has been debated before and I will trust that the rule makers know what they are talking about. It is interesting to read records of their deliberations and see what points were brought up and how they reached the decisions on different topics. They seem to generally rely on science, which is good, but don't spend enough time considering probability. They figure "better safe than sorry" which is fine until builders are spending a king's ransom on AFCIs and compensating for market conditions by using cheap devices, cut rate labor, and whatever it takes to squeeze a buck. (Yes, I realize that AFCIs will get cheaper and that they are a useful innovation.)

Time, and statistics, will tell what impact AFCIs have in general and any drawbacks of having smoke detectors on AFCI circuits in specific.

 

Probability is high. AFCI's are mandated because of shoddy electricians, plain and simple. They are there to protect the home-owner against sub-par installations where the average mindset of electricians is "How fast can I go to make more money."

Backstabing receptacles, quick-connects on recessed cans, hurriedly stapled wire, the list goes on and on of things that are done just so you can get out of there quicker.

People like that have no business being in the trade and unfortunately they are out there en' masse. I have no problem with AFCI's.... They're long over due.

 

I don't need to test our detectors--my wife cooks every nite-
I know that at least 2 of the 7 are working---

 

While that might be true and probably a hot issue to debate here I kinda doubt that the main reason for requiring them was shoddy work. I would guess it would be more for arcing extension cords, and outlets or arcing anything in the protected rooms due to age or damage. In fact extension cords are a leading cause of fires. They are often #16 or #18 wire and overloaded easily. Once they open up due to overload the wires arc and the AFCI detects this and breaks the circuit. If it did not the arcing would quite likely lead to a fire unless it burned out.

 

I will agree with you to a certain extent but as the owner of a company, I am willing to try any innovation that comes along, makes sense, and is safe according to the powers that be.
Labor is always my biggest cost and the one that is the least predictable.
As such, I am always looking for an edge.
While you may think that quick connects in a can are hack, I have been using them for several years in a variety of applications and have not seen any kind of significant failure rate.
Personally, I think that they are a great innovation. (Maybe the failures you seem to know about were due to poor instalaltion methods).
As to AFCIs, I have to agree with the point that dsc3507 brought up.
Shoddy workmanship has never been a factor in the reasoning for them.
Shoddy crap from China probably has more to do with them than anything else.

 

There have been a couple houses here in Col that have burned down and ruled to be the cause of factory recessed can connections. If it's happened here more than once then one would think it's a fairly widespread problem... But yea, perhaps someone didn't push them in all the way or maybe they loosened up over time.

It does take significantly longer to wire nut them but my boss still wants to see them on the floor, which is a good place for them IMO...