Load calculation on a three family

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jaylectricity

Senior Member
Location
Massachusetts
Occupation
licensed journeyman electrician
Two main questions in bold:

I've never done anything larger than a single meter service. I'm putting together a service for a 3 family building. It will need a 4 gang meter socket. Originally I had planned on feeding it with 2/0 copper as I would a 200 amp service. Gas stove, furnace, and dryers. A/C units for each apartment.

I decided to do a load calculation just to be sure and I think I came out to 230A, but I'm a little confused. Do I have to calculate each apartment separately and then add them up with the common area lighting load? One of the reasons I ask is that the demand factor on the A/C units is 70% if I'm counting all 3 of them together.

I rarely need to calculate a load for a service so I'm quite a bit out of practice. I dug up my notes from school from many years ago, but they only showed how to do a single family.

Also, assuming my calculation is correct am I OK with sizing the feeder from the service drop and having each meter for each apartment with it's own breakers or do I need an OCD for the total service?
 
Jay...have you given Example D4(a) Multifamily Dwelling [Annex D in the back of the NEC] an eyeballing?
 
Jay...have you given Example D4(a) Multifamily Dwelling [Annex D in the back of the NEC] an eyeballing?

You know, I had completely forgotten there was anything of the sort back there. I'll check it out tomorrow when I go back down to my truck where my code book is.
 
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