In an attempt to make the world perfectly safe, the NEC now requires an AFCI device which will cause nothing but headaches. A way for manufacturers to make money, in my opinion.

How far are we going to go with arc fault. Is it not our job to make a building as safe as possible for the owner and family? We do not require the smoke detectors and egress lighting to be on arc fault. So with the requirements of NEC 2008 should we require emergency lighting in hallways of a dwelling for egress?

The Canadian Electric Code (CEC) 2006, Rule 32-110 (a) (ii) smoke alarms shall not be connected to any circuit protected by an AFCI or GFI breaker. I wonder why such a difference btw CEC and NEC regarding this subject. Also they generally are connected to a dedicated circuit, tied together, and more often now they are also combined with a carbon monoxide (CO) detector/alarm. The CEC also recommends battery back up.

One of the concerns that I have with AFCIs and well as GFCIs is that an AFCI contains equipment ground fault protection. The amount of static electricity that the human body can carry is capable of nuisance tripping a GFCI - I am not sure if the 30 mA or 50 mA trip level in an AFCI would also be susceptible. On very cold and dry days during the winter, if I do not first ground my body and then the current carrying prongs of my electric shaver plug, the electric shaver will nuisance trip the GFCI in the bathroom. The mechanism is electrostatic induction. The static charge on my body induces and equal an opposite charge in the motor windings of the shaver. When I plug in the shaver ( without first discharging the static electricity ) the GFCI reads the static as a ground fault and trips. There is just not a way to make a GFCI that is smart enough to tell the difference between a real ground fault or a phantom ground fault from static electricity.

A similar thing can happen when a motor turns off or when the starting winding shuts off during the starting sequence. What happens is that the voltage spike from motor inductance forces a phantom ground fault pulse to flow through the winding to frame capacitance. Essentially, a small and transient version of how if you do not ground the frame of the hoist motor of a 480 volt 15 ton bridge crane the hoist ropes will have a nasty tingle voltage when the hoist is energized no matter hlw good the motor insulation is. Since 120 volt motors are built cheaply you can expect them to have more than their fair share of insulation capacitance and resistance problems.

What gets me is that I install a har-wired uninterruptible power supply in the smoke alarm circuit and that would completely defeat the AFCI.

I also consider 120 volt smoke alarms to be a bogus product. The 9 volt backup battery can be very difficult to replace for the mechanically inclined not to mention that there are a lot of people out there who are NOT mechanically inclined or who even own a ladder. The 9 volt battery could just as easily be located on the wall along with the test button. I have seen some smokes at trade shows that have an allegedly permanent battery that allegedly lives that same 10 years as the bit of radioactive material. There is also an alarm that speaks, "low battery," when the battery runs down.

In the case of one commercial customer in Cleveland, Ohio the owner, employees, and customers ignored the low battery chirp for like 3 years. One problem was that the ceiling was high enough ( 11 feet ) that the only ladder for changing the batteries required 2 people to handle it.

Sure, 120 volt smoke alarms are better than nothing, but my feeling is that a dwelling is better off to have a REAL fire alarm system. The backup battery is rechargeable and relatively easy to reach. A system that is moderately smart can periodically test the battery and if the battery is bad it can speak, "backup battery needs service or replacement."

My other feeling is that like other people have written is that an AFCI will not necessarily stop a fire from starting. In fact, I tell people that a GFCI will not stop you getting shocked, it will only stop the shock from killing you.

A further point is that General Electric and Siemens are the only 2 companies that have made a 2-pole AFCI for use with 3-wire circuits. These are common for higher load densities such as kitchens. There were some places such a Trumbull County, Ohio that required both 120 volt and 240 volt 15 ampere or 20 ampere receptacles in kitchens. Threfore, the kitchen circuits were essentially required to be 3-wire plus ground.

I have also experienced that even having 4 AFCIs in a SquareD 40 slot panelboard creates a lot of congestion because they stick so far into the gutter. SquareD would be better off to make a version that takes up an extra plle space ( like neutral switching breakers do ) in order to free up gutter space. Expect to need to use a lot of 16-slot subpanels when using SquareD.

I want to restate that there should be separate identified circuits, at least 2 per residential dwelling, to feed the smoke detectors that are required. The wiring should be identified by a red jacket, the boxes should be likewise red, and to prevent tampering the device or wiring should be installed using Torx security screws......you know the ones with the center post in them to prevent unauthorized removal, this would help prevent these circuits from being extended for use as general lighting circuits.

AFCI breakers can remove the early warning protection that smoke detectors provide for the residents of the dwelling.

South Carolina disagrees with the NFPA and modified article 210.12(B) to eliminate AFCI's for circuits serving smoke detectors.

Oregon addendums alter the code so that bedrooms only are required to have AFCI and it further exempts the smoke alarms from AFCI.

I have heard that many other states have similiar exemptions.

I would like to know if this is the only fire caused by a smoke detector. I would like to know who installed this unit (DIY0 or pro), If a pro this manufacture has a big problem. I can not see changing anything for one event..

Can we ever differentiate between a smoke detector and a smoke alarm device? If we start from now on calling them out properly, the terms will stick. They are both notification devices, one sends a signal, the other one does not; one has an alarm built-in, the other one does not.; the good part is that both "notice" the presence of smoke. Smoke detectors send a signal and have no alarms, smoke alarms do not send signals and have alarms. See NFPA 72 for more definitions. Respecfully... Lorenzo

Mike --

I don' like the idea of AFCI protection ahead of smoke detectors for the same reason that it's not allowed for fire alarm circuits.

In weighing the danger of a defective smoke detector causing a fire against the chance of an AFCI taking one off line, I feel that having an operating detector to protect the family is more important than the possiblity that an AFCI might actually stop a fire caused by a defective detector.

Of ocurse, it would be handy to know how many smoke detectors have become defective in such a way as to cause a fire.

Regards . . .

Jim

Sounds like the problem is in the cheap smoke detectors (probably made in China). Would it not be better to put some responsibility back on the manufaturer? As in the cases with the room air freshners. Contractors and homeowners need to use reputable product lines instead of the cheapest thing they can find.

I think sometimes the error is too far on the side of safety......that is here is one case in which a smoke alarm supposedly caused a fire......the question that is not answered is were the other smoke alarms operating and sounding at this time??..........also if the AFCI was there and had tripped to the off position, would that be enough to stop this fire OR was it caused by an over heated component that had already charred the circuit board which was already at a combustible temperature had caught fire and then the arcing of the 120v. feed would have tripped the AFCI? (the most likely scenario).........From your support article it seems like there was a BIG jumping to a conclusion to get support for this recent code addition.........

Another point......many wired in smoke detectors DO NOT have the battery backup mentioned in previous responses.......so if a general lighting circuit in a residential home was used as the power source for the smoke detectors and the AFCI tripped........where is the protection??...........as the fire may have already started (see the example later on).......

Since now in the fire alarm industry, fire alarm cables have a red jacket to distinguish them from other cables..........let's have a red jacketed 14/2 cable to supply ALL the smoke detectors using 2 circuits minimum in the residence and this red jacked 14/2 be fed from a standard 15 amp breaker that also has a red color or marking and be secured in the on position, also the mounting boxes for smoke detectors be made from red plastic or be colored red to identify them and the circuitry they contain.........or require that all the smoke detectors be on several (minimum 4) circuits in the residence to prevent one AFCI from removing power from the smoke detectors when it trips.......

I understand the logic behind the addition to the NFPA code for the AFCI breakers..........but let us not undo the good that has become established in a residential home with the addition of smoke detectors by having them non-functioning because of our zeliousness to provide the safest envirement possible to live in...........

Remember we can not prevent all hazards by legislation.......There is a personal level of responsibility there too..........IE, placing an electric heater too close to a bed or couch will start a fire.......when a lamp cord finally arcs and trips the AFCI shutting down the heater.......The fire is started and the AFCI did not prevent it!!.........and that AFCI may have shut down the smoke detectors closest to the fire, removing the early detection that the smoke detectors are to give the people dwelling in the residence.........i agree with their use but lets not go crazy or we will have frivolous law suits similar to holding a hot cup of coffee between you legs and getting paid for burning your thighs because the hot coffee splashed on your legs while driving your car.........

Lets work to keep smoke detectors operating...........I personally do not like AFCI breakers ahead of smoke detectors for the above reasons!!.........

I figured the reason house smoke circuits had to have AFCI protection was because people sometimes hijack the 110 in those junction boxes for other fixtures and devices.

It seems like the initial spate of faulty AFCI's has subsided. I hope this is a trend with staying power. At least the smoke detectors have back-up batteries to protect the residents incase of power failure.

I feel the real question here is whether the AFCI would detect an arc fault in the circuit board of a smoke detecctor. The reason for the question is that most smoke detectors backup is a 9 volt battery DC current.

why do we need this in every room? the added cost of this is hurting developers of multifamily buildings.

The question I often hear is: "If my building is fully sprinklered, do I still need a fire alarm system?" How would you answer it?

Wow, we now have the one in a million case where a very very small load (smoke detector) caused a fire?? (and that is IF the actual cause of the fire was the smoke detector, after all the fire caused extensive damage) As opposed to the numerious cases where a smoke detector will fail to opperate since "the AFCI tripped the circuit for the 3rd time this week" because the NEC requires a ceiling fan to be on the AFCI "protected" circuit as well. Am I the only one that thinks that AFCIs should fall under the same catagory as say Valentines day...simply made up to generate more money..?