334 vs 518

[augie47]

Situation:
New Construction of a large restaurant, building inspector states it's type III-B (??) construction, sprinkled with the kitchen area fire rated construction but the dining areas non-fire rated.
Art 334 allows NM in type III construction except places of occupancy, however, 518,4(B) allows NM where it is non fire rated construction which applies to the dining areas.
The kitchen is fire rated construction but it in itself is not a "place of occupancy"...

Can NM be used throughout the building or would the kitchen walls require metallic ???

 

[kwired]

I'm looking at 2023 NEC and 518.4(B) applies to communications, data, signal, fire alarm systems, and systems less than 120 volts?

 

[augie47]

'17 NEC {518.4(C) in '23}

 

[Dennis Alwon]

Here is the 2017 reference--Assembly Occupancy

(A) General.
The fixed wiring methods shall be metal raceways, flexible metal raceways, nonmetallic raceways encased in not less than 50 mm (2 in.) of concrete, Type MI, MC, or AC cable. The wiring method shall itself qualify as an equipment grounding conductor according to 250.118 or shall contain an insulated equipment grounding conductor sized in accordance with Table 250.122.
Exception:
Fixed wiring methods shall be as provided in

• (a)
  Audio signal processing, amplification, and reproduction equipment — Article 640
• (b)
  Communications circuits — Article 800
• (c)
  Class 2 and Class 3 remote-control and signaling circuits — Article 725
• (d)
  Fire alarm circuits — Article 760

(B) Nonrated Construction.
In addition to the wiring methods of 518.4(A), nonmetallic-sheathed cable, Type AC cable, electrical nonmetallic tubing, and rigid nonmetallic conduit shall be permitted to be installed in those buildings or portions thereof that are not required to be of fire-rated construction by the applicable building code.

 

[Dennis Alwon]

As I read (B) non rated construction it doesn't mention place of assembly but the article is for assembly occupancy. I am guess that other building codes would restrict NM in the kitchen area.

 

[kwired]

'17 NEC {518.4(C) in '23}

I see that now.

IMO the kitchen is not part of the assembly area, and 518 doesn't apply to it if it is separated by rated construction methods. This maybe could be worded a little differently but I think that is kind of what it is trying to say.

Building codes will normally require rated construction for the assembly area, probably for a kitchen as well, but may or may not be rated doors or other openings between the two in many cases either effectively making them the same occupancy area in many aspects.

 

[wwhitney]

The kitchen is fire rated construction but it in itself is not a "place of occupancy"...

Can NM be used throughout the building or would the kitchen walls require metallic ???

So this is a building code question, as per 518.2(B): Is the restaurant, including the kitchen, all a single occupancy? Or does the building have two different occupancies, one for the dining area and one for the kitchen?

Cheers, Wayne

 

[pipe_bender]

Every restaurant I have ever done and i've done a few was all EMT home runs exposed and in ceiling,
Occasionally exposed aluminum rigid in a really large kitchen not sure why,
Metal Flex or MC concealed walls occasionally EMT.
Under slab was PVC .
but I have never ever seen one in NM in a commercial kitchen. Not a code expert don't know why but thats what I have seen.

 

[augie47]

So this is a building code question, as per 518.2(B): Is the restaurant, including the kitchen, all a single occupancy? Or does the building have two different occupancies, one for the dining area and one for the kitchen?

Cheers, Wayne

Building Inspector says its a "hybrid" hence there calling it Type III-B construction.
It's a single structure with seating areas non fire rated and the kitchen area fire rated.
That, to me, is the confusing as the seating areas which have an occupancy > 100 would fall under the exception since they are of non fire rated construction. The kitchen is fire rated construction but that portion of the building is less than 100 occupancy.

 

[wwhitney]

Building Inspector says its a "hybrid" hence there calling it Type III-B construction.

Construction type and occupancy are two different things.

Oddly, the IBC does not have a definition for the word "occupancy." But it does have a whole chapter (chapter 3) dedicated to determining the occupancy, as well as instruction on how to apply different requirements to different parts of a building when a building contains multiple occupancies (namely, section 508 on mixed use and occupancy).

However, I think your question is answered by IBC 303.2. It states "Group A-2 occupancy includes assembly uses intended for food and/or drink consumption including, but not limited to: . . . Restaurants, cafeterias and similar dining facilities (including associated commercial kitchens)"

So the kitchen associated with the dining area is still Group A-2, so it is still considered an assembly occupancy. As such, per 2017 NEC 518.2(B), Article 518 still applies.

So if the 1 hour rated walls around the kitchen are required by the IBC (which I assume it is true; I'm not sufficiently versant with the IBC to quickly verify that), then 518.4(B)'s permission to use NM would not extend to the kitchen.

Actually, I'm not sure our assumption heretofore of what "required to be of fire-rated construction" means is correct. For example, maybe the IBC would require the floor under the dining room to be "fire-rated construction", so that even though walls internal to the dining area are not of fire-rated construction, the dining area as a whole would still be considered to be of "fire-rated construction", so that 518.4(B) would not apply to either the kitchen or the dining room. Again, I don't know; a greater familiarity with the IBC would be required to clarify that.

On the other hand, 518.1's scope covers only buildings or portions of buildings intended for the gathering of 100 or more people. So if you have a small restaurant, and the occupancy load (to borrow a phrase from the building code, although again I'm not clear on the details of this term) of the building is below 100, I guess that means that Article 518 doesn't apply at all, even though the Occupancy Group is A-2?

Cheers, Wayne

 

[kwired]

I was bidding a church one time, new building. More of a multipurpose room where they had both church services as well as fellowship hall activities all in same room. Then they had a kitchen and some classrooms kind of off in another part that sort of was another wing so to speak to the main area. I never got the bid but when talking to inspector the main area he said would be assembly area, the kitchen was to have a large open serving window into the main room, if it would have had one hour finish and doors he said he would let it count as non assembly area, could even use NM cable in there if that were the case. Class rooms were all small enough none were over 100 occupancy so those not assembly area either - if they had one hour finish between them and the assembly area. That been like 20 -25 years ago but don't see that would really change much. Of course if there were any suspended ceilings no NM can be run above suspended ceiling even if not within an assembly area.