Combined Apartments and Article 220

[Tainted]

In a 100+ unit apartment building, suppose you have apartment A and apartment B. Each apartment has it's own electrical panel metered separately. The tenant bought both apartments and now he would like to combine them making it into one large dwelling unit meaning the dwelling unit now has two panels metered separately. The tenant wants to renovate the combined apartment and add additional loads to it which means a calculation using article 220 must be performed.

Are we even allowed to have more than 1 service in a combined unit like this?
I think no because someone a long time ago would have had to use article 220.84 to calculate the feeder for the entire meter bank but it tells you that you can't use 220.84 if a dwelling unit is supplied by more than one feeder.

What should I do? Do I just include all the loads on the two panels using the optional method separately?

Or should I just make the combined apartment have 1 central panel and service?

 

[tortuga]

suppose you have apartment A and apartment B. Each apartment has it's own electrical panel metered separately. The tenant bought both apartments and now he would like to combine them making it into one large dwelling unit

Are we even allowed to have more than 1 service in a combined unit like this?

Are you sure these are services? Typically there would be one service in the basement with the mains and meters and those panels would be feeders.

 

[Tainted]

Are you sure these are services? Typically there would be one service in the basement with the mains and meters and those panels would be feeders.

No it's not a service. I'm just using layman words

 

[tortuga]

I dont think there is an issue if they are feeders as defined in article 100.
You'll just have to do a load calc for each one, and provide proper diagrams per 215.5

 

[Tainted]

I dont think there is an issue if they are feeders as defined in article 100.
You'll just have to do a load calc for each one, and provide proper diagrams per 215.5

215.5 is interesting, this is the first time I ever knew about it. But 215.5 is only required if the AHJ ask for it.

 

[tortuga]

Yeah AHJ is all about that here, I also have had that among other things required by the owners insurance 'underwriter' when they do walk thru of old buildings.

 

[NAjxBUEEdA7PoKoX7vD2]

The building is built. Are we trying to determine if the 3000 amp service needs to be replaced with a 3050 amp service?

After I started working with multi-family load calcs in Excel, I quickly concluded that Article 220 was written before Excel was available. For the most part, load calculations are about applying demand factors, or fitting to the curve. The field measurements producing the Article 220 curves must have been made a long time ago. To propose Article 220 updates, one would have to have curves from current field measurements. In addition, how do electric instantaneous water heaters and car chargers fit into load calcs? It is no one's job to answer those questions.

Here are two Article 220 multifamily load calc sawtooth graphs that I posted about two weeks ago. The Article 220 requirements that produced them were not graphed before they were approved. Section 220.85 is an obvious admission of this same mistake in writing the multi-family optional method sawtooth demand factors.