# AFCI protection - Mechanical rooms



## Beniah Naylor (Oct 19, 2021)

AFCI protection is required in:

*(A) Dwelling Units. All 120-volt, single-phase, 15- and 20-ampere branch circuits supplying outlets or devices installed in dwelling unit kitchens, family rooms, dining rooms, living rooms, parlors, libraries, dens, bedrooms, sunrooms, recreation rooms, *_*closets*_*, hallways, laundry areas, or similar rooms or areas shall be protected by any of the means described in 210.12(A)(1) through (6).*

When does a mechanical room qualify as a closet or similar room/area and need AFCI protection on the 120v outlets? Does it ever? Which, if any, of the following would you make someone put in AFCI protection?

(1) A mechanical closet, barely big enough to fit a furnace and water heater, located roughly in the middle of the main floor, accessed by a door off the same hallway as bedrooms and bathrooms.

(2) A mechanical room in a finished basement, accessed from a finished den or family room. The mech room is unfinished, but it is a good sized room, maybe 10' x 12'.

(3) A mech room that is small like the first one, but can only be accessed from the garage, with the rated garage wall separating the house from the garage and mech room.

(4) An unfinished basement, with the mech room located off to one side.

Our jurisdiction has been amending the AFCI requirements (except for bedrooms) out of the code for years, but we are wanting to finally adopt them with the 2020 NEC. Any help/insight given will be appreciated.


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## e hilton (Oct 19, 2021)

1 & 3 … no. 
 2 & 4 … yes for any outlets intended for general convenience.


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## ICE (Oct 19, 2021)

1&3 Yes.  That applies to new construction but not to a furnace replacement in the same location as before.


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## Beniah Naylor (Oct 20, 2021)

e hilton said:


> 1 & 3 … no.
> 2 & 4 … yes for any outlets intended for general convenience.


Yes for outlets intended for general convenience, why is that? Would you be trying to prevent nuisance tripping on the furnace by not putting it on an AFCI, but covering everything else?


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## Beniah Naylor (Oct 20, 2021)

ICE said:


> 1&3 Yes.  That applies to new construction but not to a furnace replacement in the same location as before.


Is this because the larger rooms are not "closet sized" and therefore aren't similar rooms?


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## ICE (Oct 20, 2021)

Beniah Naylor said:


> Is this because the larger rooms are not "closet sized" and therefore aren't similar rooms?


2&4 are rooms that have no similarity to any rooms on the list.  Some might say that a 10’x12’ room with a furnace is a candidate for classification as a closet.  I have encountered clothes closets that are larger than that so I would agree with the argument were it presented.  However it is a stretch.  In the long run, more AFCI is better than less AFCI and when the code included closets and hallways it became apparent that we are trending “more”.


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## e hilton (Oct 20, 2021)

Beniah Naylor said:


> Would you be trying to prevent nuisance tripping on the furnace by not putting it on an AFCI, but covering everything else?


Yes.  Once the furnace is up and running, there will probably never be a change to the electrical path, and very little human contact.  Maybe change the filter once a month, probably less, maybe an annual service.  

On the other hand, the convenience outlets are liable to have a worn extension cord plugged in, over loaded plug strips, that kind of thing.


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## Rick18071 (Oct 20, 2021)

e hilton said:


> 2 & 4 … yes for any outlets intended for general convenience.


I can't find this in the code.


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## e hilton (Oct 20, 2021)

Rick18071 said:


> I can't find this in the code.


That’s possible.  What code do you find?


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## Glenn (Oct 20, 2021)

I guess I will be the rebel here.  AFCI is a safety technology that has been slowly working it's way further and further into the code since the 1999 NEC.  If the proponents of AFCI had their way, I suppose every circuit would require AFCI... many years ago...  (This is not a attack statement, just as assumption of fact)

So, considering its taken two decades to get this far and the NEC is a minimum standard, I will er to the side no AFCI when interrupting.  In absence of code there is total freedom.  So I believe in question of whether a code requirement exists, the default should be it's absence (depending on research that may reveal something unique).  That may not make sense to everyone, and that's okay.

There is one heck of a specific list under AFCI, just as there are specific lists elsewhere in the NEC.  "basement and utility room" are not in the list, but they are used in other provisions of the NEC when something is required of them.  So when a space is identified and recognized in the same code, I would less likely assume they are part of a "or similar spaces" from any other part of the code. They have been given a name in the code for a reason.  I expect it to be used if I am to assume it is being referenced.

As for storage room, I can't speak for the NEC, but the IRC is also clear when referring to a closet vs. a storage room in a number of provisions.

1, 2, 3, 4 = No


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## ICE (Oct 20, 2021)

The only closet that falls out of NEC purview is a water closet.  Be it a clothes closet, mechanical closet, broom closet or a toy closet….a closet is a closet.


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## Beniah Naylor (Oct 21, 2021)

Glenn said:


> I guess I will be the rebel here.  AFCI is a safety technology that has been slowly working it's way further and further into the code since the 1999 NEC.  If the proponents of AFCI had their way, I suppose every circuit would require AFCI... many years ago...  (This is not a attack statement, just as assumption of fact)


Absolutely true.



Glenn said:


> So, considering its taken two decades to get this far and the NEC is a minimum standard, I will err to the side no AFCI when interrupting.  In absence of code there is total freedom.  So I believe in question of whether a code requirement exists, the default should be it's absence (depending on research that may reveal something unique).  That may not make sense to everyone, and that's okay.


Valid approach - we may go this way, especially since we are going from basically no AFCI to full AFCI in one code cycle, to try to ease transition.


Glenn said:


> There is one heck of a specific list under AFCI, just as there are specific lists elsewhere in the NEC.


It is, but it is poorly written in my opinion. Why don't they say "all 15- and 20-amp circuits in a dwelling unit shall be AFCI protected. Exception: Bathrooms, Garages, attics, certain dedicated equipment, etc..." That is how everyone I know tries to read that section - they see all the room names and they say "what isn't on the list?"


Glenn said:


> "basement and utility room" are not in the list, but they are used in other provisions of the NEC when something is required of them.  So when a space is identified and recognized in the same code, I would less likely assume they are part of a "or similar spaces" from any other part of the code. They have been given a name in the code for a reason.  I expect it to be used if I am to assume it is being referenced.
> 
> As for storage room, I can't speak for the NEC, but the IRC is also clear when referring to a closet vs. a storage room in a number of provisions.
> 
> 1, 2, 3, 4 = No


The only hole I can poke in that theory is that the NEC added a definition for "clothes closets", but has no definition of a room that is simply a "closet", despite many references throughout the code that simply use the word "closet", instead of the phrase "clothes closet". This leads me to believe that there are closets for clothes, and there are closets for other things - and nobody knows what the other things are.

The IRC is clear enough on the difference between closets and storage rooms, but the NEC not so much.


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## Paul Sweet (Oct 22, 2021)

I believe NEC defines "clothes closet" because of the restrictions on light fixture locations in 410.16.


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## jar546 (Oct 22, 2021)

ICE said:


> The only closet that falls out of NEC purview is a water closet.  Be it a clothes closet, mechanical closet, broom closet or a toy closet….a closet is a closet.


+1


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