Residential or Light Commercial?

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shockingdave

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I am upgrading a private Christian school dormitory with an attached deans apartment. I have a 400 amp meter combo to two 200 amp panel approx 30' away. If this falls under residential, then 2/0 can be considered, if it is light commercial then 3/0 must be considered according 310.15/16. The wiring for this is located in the deans apartment which is physically attached to the dormitory. Only the second panel box has wiring that leaves this apartment and enters the dormitory. Does this fall under Residential or under Light Commercial?
 
I agree its not an individual persons home. I know thats not the definition of dwelling but its how I think of it when thinking residential. It may be likely to have higher heating,cooling, and lighting loads than a residence.
 
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Art 100 defintions:

Dwelling Unit. A single unit, providing complete and independent living facilities for one or more persons, including permanent provisions for living, sleeping, cooking, and sanitation
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If that defintion is met it is a dwelling unit no matter what else is located in the same building. That also means all other dwelling unit requirements must be met such as 210.52, GFCI and AFCI requirements,

If this space does not have permanent provisions for cooking, or sleeping, or has no bathroom within the unit then it is not a dwelling unit. It is a dormitory room, office, or other space.

I have a 400 amp meter combo to two 200 amp panel approx 30' away....The wiring for this is located in the deans apartment which is physically attached to the dormitory. Only the second panel box has wiring that leaves this apartment and enters the dormitory.
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Only the deans apartment is potentially a dwelling unit, the rest of the building is not. The two feeders you mention can not use Table 310.15(B)(6) because they are not feeding "all loads that are part or associated with the dwelling unit." as is mentioned in 310.15(B)(6). If you had a feeder supplying the dwelling unit only and it supplies all of the dwelling unit load then you can use table 310.15(B)(6) to size that feeder.


It may be likely to have higher heating,cooling, and lighting loads than a residence.
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I think it is more likely to require less heating and cooling than a stand alone residence of the same size. I'm talking the dwelling unit itself and not the entire building. For starters there will be likely be conditioned spaces adjacent to it at least on one side maybe even above or below. That means there is less exterior wall, floor, roof, and even windows and doors which are the biggest heat loss culprits, to lose conditioned air to as compared to a stand alone residence.
 
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The question was not if its a dwelling or not, the question is the TYPE of construction.


The service the OP referes to is 400 amp which is not going to be an individual uni tit will be the load for the building which will include common areas. Parking lot lighiting, halways and common HVAC will likely be larger than in a similar residential environment.
 
mikeames said:
The question was not if its a dwelling or not, the question is the TYPE of construction.


The service the OP referes to is 400 amp which is not going to be an individual uni tit will be the load for the building which will include common areas. Parking lot lighiting, halways and common HVAC will likely be larger than in a similar residential environment.
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I think the question was whether or not table 310.15(B)(6) can be used to size the feeders, which the answer is directly effected by whether the feeder is supplying a dwelling regardless of type of construction. Whether you are wiring a house of straw, house of sticks or a house of bricks you can still use this table to size the main feed as long as it meets the definition of dwelling. The OP has a dwelling within a building with other areas. The supply to the dwelling only qualifies for table 310.15(B)(6). Since the supply he is questioning is not the sole supply for the entire dwelling and it feeds non dwelling loads he can not use this table.
 
Maybe I was confused about the situation. The service is comercial but one panel feeds a dwelling..... ok.
 
He has a 400 amp meter combo but it does not matter whether this is a dwelling or not. You still need 3/0 to each of the 200 amp disconnects since neither panel carries the entire load of the service. So to answer his question-- 3/0 NOT 2/0
 
thanks for the input

thanks for the input

Thanks for the input, I thought it would be 3/0 but was uncertain. The reason for my uncertainity was this. This dormitory actually has 3 meterbases, with 2 at 200 amps and now one at 400 amps. There are two deans apartments at each end, literal apartments with kitchens, bathrooms and2-3 bedrooms and each apartment has a small office located inside of the main dormitory in the middle between the two. When I had to electrically remodel the second floor of this building, I installed 7 PTAC A/C units on the second floor of the dormitory along with one and prospectively 2-5 ton A/C to be installed later. The A/C load is being located in a seperate panel all of its own in the primary deans apartment, next to a panel box used to power the deans apartment and the small office. All meter bases and distribution systems are located in each of the two apartments. and branch from there. Last question there, even though these are completely self-contained apartments, then the entire structure including the apartments fall under the commercial code- correct?
 
First off there is no commercial code. If the building fits the definition of a dwelling the it would be considered a dwelling and those sections in the code would apply.
 
Dennis Alwon said:
First off there is no commercial code. If the building fits the definition of a dwelling the it would be considered a dwelling and those sections in the code would apply.
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Even just an area of a building that fits the definition of a dwelling is a dwelling.

It is correct that there is no residential or commercial code (within regards to the NEC) there is only one NEC with certain sections that apply to dwellings only. Some of the most common sections that apply to dwellings only are 210.8(A), 210.12(B), 210.52, certain load calculations in 220, 310.15(B)(6), and 406.11. There will be occasional other articles that mention something that applies to dwellings only.
 
thanks for input, so much to learn

thanks for input, so much to learn

Thanks for input, so much still to learn, appreciate your patience and cooperation with me as I learn. My mentor/trainer still shakes his head every so often and chuckles quietly under his breath, he knows I am learning though.
 
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