RE: 300.22c - Other Space Used for Environmental Air

Status
Not open for further replies.
E

enigma-2

Member
Location
northern Indiana
RE: 300.22c - Other Space Used for Environmental Air

Art 300.22 C states "applies to space used for environmental air-handling purposes other than ducts and plenums" ... "It does not include habitable rooms or handling." (FPN states "The space over a hung ceiling used for environmental air-handling purposes is an example of the type of other space to which this section applies."

We have an AHJ which has tagged us for having a utility closet, with a door, which contains only a residential gas furnace. The return air enters the compartment via a grill, and is allowed to circulate into the furnace's air handler.

His contention is that this space's primary purpose is for air handling. We disagree, based on the the use of the phrase "primary use". We see this to mean that the space's ONLY purpose is to move air, not incidental to this use. (It's not that big deal to use ACT cable, but we feel that he is wrong and would like to at least have the option to wire it with NM cable.)

We referenced page 274 of the 2005 NEC Handbook, but the AHJ believes that this publication further supports his position. :rolleyes:
(The AHJ is part of a government agency).

Does anyone know of any reference where this this has been interpreted or further examined? It's been disputed for over a year and we would like to get this settled.
 
I don't have any other references, but I did look at the sections mentioned and at the drawing in the Handbook (Don't have 2005 but have 2008. I don't think there were any changes).

It seems to me the AHJ is on target here. Exhibit 300.19, page 290 in the 2008 NEC Handbook demonstrates a "habitable" area on the left which is exempt from 300.22(C) and an air-handling room on the right, which must comply with 300.22(C).

It is my contention that the primary purpose of the room on the right is "air handling." I think your room would fall under the same consideration.
 
RE: 300.22c - Other Space Used for Environmental Air

RE: 300.22c - Other Space Used for Environmental Air

The illustration (Exhibit 300.20) shows "Other space used for environmental air (such as space above suspended ceiling)" at the top of the drawing, indicating that, THAT is the "other space" in which they are referencing.

I don't feel that the mechanical room was intended as the target of the article (the drawing is ambiguous in the Way it's presented).

Looks like I may have to request a formal interpretation from NFPA on this one.

Thank you for your opinion.
 
I see what you are saying now. The drawing is ambiguous as you mention. But I am still thinking that the "air handling" room on the right in the diagram needs to comply with the requirements.

Good question, perhaps others will chime in. Also, if you get an interpretation from the NFPA, please post the results here.

Thanks!
 
enigma-2 said:
Art 300.22 C states "applies to space used for environmental air-handling purposes other than ducts and plenums" ... "It does not include habitable rooms or handling." (FPN states "The space over a hung ceiling used for environmental air-handling purposes is an example of the type of other space to which this section applies."
Click to expand...

The highlighted portion above is misquoted from the NEC.

Correct: "It does not include habitable rooms or areas of buildings, the prime purpose of which is not air handling"

You stated the room in question contains ONLY a furnace and this furnace obtains its supply air from said room via a grill in the door. You termed this room as a "utility closet" but it sounds to me as though this room was intended for use as a "furnace closet" in which case the room's primary purpose is for air-handling and nothing else.

I would say the AHJ is justified in their red-tagging.

Let's assume the following make-believe scenario: The same furnace has directly attached ducting that pulls supply air from the attic of the house and this closet is only a space for the furnace to reside. I would then say you would be right and the AHJ is wrong because no air-handling is being done in that room but rather in the attic.

In either case the AHJ may have their own rules and definitions of "air-handling rooms". The simple fact that a furnace or blower is in that closet may, by the AHJ's definition, be an air-handling room regardless of what the NEC says.
 
Yes. I agree with the Inspector (No we all do not hang around together) The mechanical closet as you explain meets 300.22(C)(1) So only the wiring methods mentioned shall apply. I meant to ask. What is ACT cable?
 
Last edited:
RE: 300.22c - Other Space Used for Environmental Air

RE: 300.22c - Other Space Used for Environmental Air

I've just emailed a formal request for interpretation to NFPA.
---------------------------------------------------------
It's still our feeling that the primary purpose of a HVAC compartment is for the installation and operation of equipment, with a possible secondary use to allow environmental air to circulate.

Return air may or may not actually exist in the compartment; should the airflow be ducted into the furnace through a duct. In which case the compartment is still performing it's primary function of an enclosure for the equipment.

We continue to base our argument on the NEC FPN: "The space over a hung ceiling used for environmental air-handling purposes is an example of the type of other space to which this section applies."

The important part here is that the NEC is clarifying that it is NOT talking about the equipment room, ONLY the air-handling space OVER the living area.

The distinction is important in that many different scenarios may be included into too-broad an interpretation.

However they rule, I'll post the NFPA's response here when received.

Thanks to all who responded.
 
Status
Not open for further replies.
Top