use of 220.82

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So many times I've received load calculations, per 220.82, for more than one set of dwelling service entrance conductors/overcurrent devices, and for feeders fed from the service panel/load center. My other concern is when other loads, such as pool and/or dock equipment and landscape lighting are included in the 220.82 optional dwelling calculation. It just seems these loads are not ?part of? the ?dwelling? even though they are ?associated? with the dwelling, and not applicable to this calculation.
I've tried to post this same comment to the recent newsletter about dwelling load calculations per the 2014 NEC?, but I keep getting an error message.
 

Smart $

Esteemed Member
Location
Ohio
I say 220.82(B) first line includes 220.14.

I see nothing in 220.82 that exempts other load. Assuming that they are known.
I don't see it.

Are we talking the same thing? I understand OP to be about including loads not in or directly associated with the dwelling unit in the 220.82 calculation. Those loads should be included in a separate Standard Method calculation. Then both summed together to determine the service.
 

jxofaltrds

Inspector Mike®
Location
Mike P. Columbus Ohio
Occupation
ESI, PI, RBO
I don't see it.

Are we talking the same thing? I understand OP to be about including loads not in or directly associated with the dwelling unit in the 220.82 calculation. Those loads should be included in a separate Standard Method calculation. Then both summed together to determine the service.

He says both, Included and not included.

Now to your point. Are you saying add 220.14 and 220.82 together?
 

Smart $

Esteemed Member
Location
Ohio
He says both, Included and not included.

Now to your point. Are you saying add 220.14 and 220.82 together?
It's not really 220.14. That's under branch circuit calculations

Some of the service load will be Part III, some Part IV. Add those.
 

jxofaltrds

Inspector Mike®
Location
Mike P. Columbus Ohio
Occupation
ESI, PI, RBO
It's not really 220.14. That's under branch circuit calculations

Some of the service load will be Part III, some Part IV. Add those.

220.82(A) removes Part III.

Isn't 220.82(B) talking about branch circuits?

IMHO 220.82 applies to all loads present at construction. 220.83 if it's existing.

And since it is not existing that leaves 220.82.
 

JoeStillman

Senior Member
Location
West Chester, PA
My company does lots of multi-family jobs, sometimes in mixed-use buildings. We put our load calc spreadsheet right on the drawing with the single line and it passes permit review every time. There is one for each typical dwelling unit (220.82) and one for the whole building (220.84). Some buildings get a service at each end. Then we calculate each meter center as if it was one building.

We apply 220.82 only to the individual dwelling units, not to any house loads. We size the service for each apt/condo with that. Then we take all the dwelling units together to calculate the multi-family part of the service. We use 220.84 almost always, even when there is gas cooking. Sometimes, we can refine it a bit by using 220 Part II and III (articles 220.10 to 220 61) using various separate diversity factors, but that is complex and doesn't come out much smaller than 220.84 anyway.

Only after the aggregate of all dwellings has received the appropriate diversity factor, we calculate the non-resi parts of the building at 100% non-continuous plus 125 % of continuous. This is added to the aggregate dwelling load from 220.84 to get the total service size. It's always a clean cut because there is a separate meter for the common loads.

For a high-rise building, there is typically a panel on each floor with separate meters for each dwelling unit. That panel gets an aggregate load with a 220.84 diversity factor. Then we apply a lower diversity factor for the riser feeding all floors because there are more dwelling units on the riser.

Since we always pass review with this technique, we are probably oversizing it, but none of our buildings has burned down either.
 

Smart $

Esteemed Member
Location
Ohio
220.82(A) removes Part III.

Isn't 220.82(B) talking about branch circuits?

IMHO 220.82 applies to all loads present at construction. 220.83 if it's existing.

And since it is not existing that leaves 220.82.
Note title of 220.82... "Dwelling Unit".

Loads not directly associated with the "dwelling unit" cannot be part of the optional calculation, especially if they are outside the physical bounds of the dwelling unit... IMO
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
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.
The very definition does not exclude other things as part of the dwelling unit.

If you have a detached garage is it part of the dwelling unit?

110.16 requires arc flash labeling of panelboards "in other than dwelling units". Are you claiming that a residential pool panel now requires arc flash labeling since it is not part of a dwelling unit?
 

Smart $

Esteemed Member
Location
Ohio
Yes. The load is part of the dwelling unit service.
What section or definition confirms that assessment?

Let's say the house is a One-Family Dwelling... which is defined as a building that consists solely of one dwelling unit. The shop is another building.

PS: Whether the load is part of the service is not in question. It's whether the shop load can be included in the optional calculation of 220.82.
 
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david luchini

Moderator
Staff member
Location
Connecticut
Occupation
Engineer
What section or definition confirms that assessment?

220.82. Assuming the dwelling unit is served by a single set of service conductors with an ampacity of 100 or greater (less than 100A, 220.82 doesn't apply.) The outbuilding in your example is part of the "total connected load" served by that set of service conductors.
 

Smart $

Esteemed Member
Location
Ohio
220.82. Assuming the dwelling unit is served by a single set of service conductors with an ampacity of 100 or greater (less than 100A, 220.82 doesn't apply.) The outbuilding in your example is part of the "total connected load" served by that set of service conductors.
220.82(A)... "This section applies to a dwelling unit having the total connected load served by a single 120/240-volt or 208Y/120-volt set of 3-wire service or feeder conductors with an ampacity of 100 or greater."

The shop is not a dwelling unit.
 
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