Calculations

[Preet]

Can we use demand calculations NEC 220.82 if incoming service to the site is 208, 3phase, and then feeding different apartments with 208V, 1 phase?

 

[Preet]

Can we use demand calculations NEC section 220.82 for each dwelling unit, if incoming service to the site is 208, 3phase, and then feeding different apartments with 208V, 1 phase?

 

[tortuga]

220.82 is only for one dwelling unit. For the service load for two or more dwelling units you use 220.84.

 

[Preet]

Can we use demand calculations NEC section 220.82 for each dwelling unit to feed with 208V, 1 phase, while incoming service to the site is 208, 3phase?

220.82 is only for one dwelling unit. For the service load for two or more dwelling units you use 220.84.

Yes I am applying 220.82 to each dwelling unit separately. I think 220.82 indicates it can be applied to a single dwelling unit whether it separate building or in a multifamily dwelling

 

[Preet]

So my question is still there can we apply 220.82 while site itself has 208, 3ph (each apartment will have a feed 208, 1 phase) incoming service?

 

[tortuga]

So my question is still there can we apply 220.82 while site itself has 208, 3ph (each apartment will have a feed 208, 1 phase) incoming service?

Yes your referring to a 'open wye', many places in the code refer to 'open wye' systems, such as

Article 220 220.61(C)
"a 3-wire circuit consisting of 2 ungrounded
conductors and the neutral conductor of a 4-wire, 3-phase,
wye-connected system"

And a slight variation in Article 310.15 (E)(2), 400.5(A), 520.44
"a 3-wire circuit consisting of two phase conductors
and the neutral conductor of a 4-wire, 3-phase, wye-connected
system"

Open wye is often confused with with split phase systems where neutral current can sum to 0.
the NEC should really add a definition of open-wye to assist code users in understanding these systems, and the way its referenced technically but unintentionally exempts a open wye configured transformer bank