Why AFCI breaker on smokes, but not on bathroom?

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Old 01-12-17, 11:43 AM
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Why AFCI breaker on smokes, but not on bathroom?

Maybe a dumb question, but why would an AFCI breaker be required on a dedicated hard wired smoke detector circuit, but not on a dedicated bathroom (receptacle & light) circuit?

Or am I misunderstanding the requirements?
 
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Old 01-12-17, 11:53 AM
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The specific details of the AFCI requirement have changed at each code cycle for the last several, so depending on exactly which NEC version you're talking about the answer may be slightly different.

But to directly answer, when AFCI circuit were first introduced in the early 2000s NEC required AFCI protection for all outlets in bedrooms. Fire code required hardwired smoke detectors in all bedrooms. Therefore, hardwire smokes had to be on an AFCI protected circuit.

Subsequent revisions (and local amendments) in the last 15 years or so have bounced around on AFCI required, optional or forbidden for smoke detector circuits with the moral of the story being check with your local building department.
 
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Old 01-12-17, 06:16 PM
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Definitely check with the inspector.

In the house I just finished.. the hardwired smokes were on the 15A non AFCI circuit for basement lighting.

In a home.... the hardwired smokes get connected to a lighting circuit.... not a dedicated circuit.

I would pretty much fight for my smoke detectors to be on a non AFCI protected circuit for life safety.
 
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Old 01-13-17, 09:08 AM
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Here in Minnesota they are on their own dedicated circuit.

I'll have to call the inspector and see what they say. Seems pointless to have AFCI on a circuit with such little draw (0.4 watts per smoke, from what I read) and no receptacles.
 
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Old 01-13-17, 10:08 AM
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The NEC calls for the afci protection based on the area the circuit serves, not the load. It also does not call for a dedicated circuit, but some areas have local amendments that do.

There should be no issue with a smoke alarm on a afci protected circuit. Even if there was an issue the smokes still, have battery power to protect you.
 
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Old 01-13-17, 02:29 PM
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So what exactly does AFCI on a smoke circuit protect from? I guess it was my understanding that it was to protect from frayed device cords or a compromised wiring, which would cause a series arcing situation.

I also thought that with a series arcing situation from a broken wire, you need a load on the other end - again something you won't get with a 4 watt total current draw (assuming 10 smokes on a circuit)....

but you would with a 1800 watt hair dryer in a bathroom. So again - why smokes, but not bathrooms?
 
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Old 01-13-17, 02:51 PM
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People sleeping in bedrooms are more vulnerable should something happen and a fire start.

The dedicated circuit is so that they cannot be turned off, or at least without removing a safety device like a breaker lock.
 
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Old 01-13-17, 03:25 PM
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An arc fault can be caused by a malfunctioning device, a cable with a manufacturing defect or installation damage, or an external force like a leaking roof, rodent damage or nail driven into the wall. The normal load is not really relevant when looking at fault conditions.
 
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Old 01-14-17, 06:01 AM
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MN is currently on the 2014 NEC. That code requires any "outlet" that is in bedrooms, living rooms, parlors, family rooms, basically every room other then the bathroom, to be AFCI protected. An "outlet" is any location where electric power is utilized. This includes lights, smokes, switches, receptacles, etc.

MN is in the process of adopting the 2017 NEC. Normally that will go into effect July 1, 2017. The 2017 NEC requires AFCI protection in all locations in a dwelling, no exceptions.
 
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Old 01-17-17, 02:50 PM
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Thanks. Sounds like I need to hurry and get my rewiring done!

I just don't get though, why 2014 will allow me to run 50 ft of 12 gauge romex to a bathroom, which draws damn near the full 20 amps, and it doesn't need to be afci, but the same run in 14 gauge with a tenth of an amp load needs to be afci.
 
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Old 01-17-17, 03:01 PM
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As I stated before, normal/expected load is not relevant when looking at faults. Faults happen when things don't go as planned. Neither breaker would trip on a circuit with no arc faults and no overload. The breaker is there for when the unexpected happens.
 
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Old 01-17-17, 05:39 PM
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So do you think a poorly and loosely twisted wire nut (series arc situation) on a receptacle pigtail would create a greater fire risk with a 2 watt night light, or a 1800 watt curling iron?
 
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Old 01-17-17, 05:57 PM
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The Code does not know that load will be on a circuit. While the arcing from the 2 watt night light would be minimal, (although still a hazard) it would be a much larger issue when you, or somebody else, plugs in a vacuum on that circuit.

As I mentioned earlier, if you wait about 6 months you would install an AFCI on the bathroom circuit as well.
 
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Old 01-17-17, 06:32 PM
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Well they do, within reason, which is why they mandated 20 amp receptacle circuits in bathrooms. Women beauty devices draw lots of power!

So with that 2017 code revision, are AFCI breakers to the point of reliability that we would put them on a furnace circuit yet?? Or what is exempted from Afci?

Personally, I think the whole Afci mandate is an expensive racket...
 
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Old 01-17-17, 08:09 PM
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If an inspector follows the letter of the code with the definition of an "outlet" all 120v 15 and 20 amp circuits in a dwelling are required to be AFCI protected. Nothing under the 2017 code is exempted in a dwelling from AFCI protection. A furnace is technically an "outlet" and would require AFCI protection, however, some inspectors will allow some things to be exempted. It is up to the AHJ.

Personally, I think the whole Afci mandate is an expensive racket...
I would agree. It is something that has been pushed by insurance companies to basically move the costs from them to the homeowner. While I would agree that they can prevent fires, we are spending a billion dollars to save a million dollars.
 
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