AFCI in an outbuilding on a residential property.

kwired

Electron manager
Location
NE Nebraska
CAFCI are devices that are said to detect and clear both series and parallel arcing faults. The original AFCIs were branch circuit and feeder AFCIs. The combination AFCIs have been required starting with the 2011 code. Note this is not to be confused with a dual function AFCI which provides combination AFCI protection and GFCI protection.
The originals were just called AFCI's. Kind of like they didn't call it World War 1 until there was a World War 2. They were the new miracle that would detect all arcing faults and we were promised they would do some the things they later said the combination type will now do.
 

jaggedben

Senior Member
Location
Northern California
Occupation
Solar and Energy Storage Installer
Since the OP didn't describe a sleeping area, arc fault protection is not required. All the areas that require arc fault protection are defined in article 100 as including sleeping areas.

That is as long as the AHJ doesn't come to believe this is a new dwelling unit in disguise and decide to start enforcing rules for dwelling units.
 

mtnelect

HVAC & Electrical Contractor
Location
Southern California
Occupation
Contractor, C10 & C20 - Semi Retired
An ADU has sleeping, bathing and cooking. There is another structure name for a space that is only sleeping and bathing. In WA we have ALQ or Accessory Living Quarters. Basically a place to put your annoying high school child. The NEC will probably have to catch up with terminology to make the requirement more clear.

In California, it's called a JADU (Junior Accessory Dwelling Unit). It's where you turn a bedroom into a rental. It must have a kitchenette and dedicated entrance.
 

James L

Senior Member
Location
Kansas Cty, Mo, USA
Occupation
Electrician
Since the OP didn't describe a sleeping area, arc fault protection is not required. All the areas that require arc fault protection are defined in article 100 as including sleeping areas.
Can you run that out a bit farther?

Arc fault protection is required in quite a few areas other than sleeping areas - hallways, closets, laundry areas, dining rooms, kitchens, etc.

Or am I misunderstanding what you're saying?
 
Location
Seattle
Occupation
Electrician
Can you run that out a bit farther?

Arc fault protection is required in quite a few areas other than sleeping areas - hallways, closets, laundry areas, dining rooms, kitchens, etc.

Or am I misunderstanding what you're saying?
210.12 clearly call out a number of rooms in a "Dwelling Unit". Those rooms also exist in office building and AFCI are not required in there.
Article 100 clearly defines a "Dwelling Unit". The code needs to be clarified. At this time the AHJ is the deciding force. I think some feel the room may turn into a bedroom for a teenager and that would in my mind be a good place to have AFCI.
 

jaggedben

Senior Member
Location
Northern California
Occupation
Solar and Energy Storage Installer
210.12 clearly call out a number of rooms in a "Dwelling Unit". Those rooms also exist in office building and AFCI are not required in there.
Article 100 clearly defines a "Dwelling Unit". The code needs to be clarified. At this time the AHJ is the deciding force. I think some feel the room may turn into a bedroom for a teenager and that would in my mind be a good place to have AFCI.
Correct.

The code doesn't need to be clarified. Ultimately these things require common sense and judgment calls. The purpose of your clients construction needs to be clarified. It sounds like it could potentially be used as either a dwelling or a guest room. The burden is probably on you and your client to show otherwise if the AHJ is suspicious about that and you don't want to install AFCIs.
 

tortuga

Code Historian
Location
Oregon
Occupation
Electrical Design
In California, it's called a JADU (Junior Accessory Dwelling Unit).
Yeah good point and a JADU = definition of 'guest suite' in the NEC
Nice thing about that is the 240.24(B)(1)(2)
Correct.
It sounds like it could potentially be used as either a dwelling or a guest room.
In the OP's case the bedroom can't be a dwelling unit unless it has a kitchen and a bathroom so its a guest room or guest suite as per NEC definitions.

Where the code messed up is when they say guest suites 'of hotels and motels', they should just nix that 'hotels and motels' and leave it as 'guest suites and guest rooms', the CMP would not have had to add all the other stuff about fire stations etc in the 2023.
So I'd say because of way the 2020 and 2023 are worded no AFCI required.
 
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Can you run that out a bit farther?

Arc fault protection is required in quite a few areas other than sleeping areas - hallways, closets, laundry areas, dining rooms, kitchens, etc.

Or am I misunderstanding what you're saying?
The key is that all those types of rooms that require AFCI are IN a dwelling unit. If you had a stand alone structure that was ONLY a laundry room, it would not require AFCI, even though laundry rooms IN dwelling units require afci. A structure is either a dwelling unit or it is not.
 

James L

Senior Member
Location
Kansas Cty, Mo, USA
Occupation
Electrician
The key is that all those types of rooms that require AFCI are IN a dwelling unit. If you had a stand alone structure that was ONLY a laundry room, it would not require AFCI, even though laundry rooms IN dwelling units require afci. A structure is either a dwelling unit or it is not.
According to a strict reading of "only" the NEC, a stand alone sleeping cabin isn't a dwelling unit, either.

That's why I was curious about the reference to sleeping area
 
It is a strict reading, because it ignores obvious intent. And it also depends on who you ask.

NEC is not the only say-so
A jurisdiction is welcome to adopt an amendment saying (something like) "AFCI's shall be required in any structure where people are likely to sleep." but as it is, the NEC says nothing of the sort. We mare in trouble if inspectors start citing codes based on their opinion of the intent.

I suppose an AHJ could call it a "dormitory" as the NEC does not provide a definition, but that would be bogus IMO.
 
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