Just so you know all (or at least the vast majority of) municipalities prohibit unlicensed persons from doing electrical work in multi-family dwellings. You really need to hire a licensed electrician who could answer your questions and ensure the work is done safely and to code.

Thanks for the info, but my area of PA doesn't require contractor licensing.

FWIW, I am an electrician, but I do commercial work and unfortunately, as an IBEW member, our apprenticeship and continued work doesn't deal with the code all that much. Most of the code issues are dealt with by the engineers, very little is left for us to decide, some people call us "electrical installers" which is true to a point.

On an issue like this thread topic, I'd be happy to learn if people could help by citing the code or giving opinions.

There's a table in Article 220.49 that might help with the load calculations. Properly sized feeders is covered in Article 215.2 and you can find wire ampacity tables Article 310.16.

Hope this helps!

220.49? I don't see that in 05 or 08.

In 310.16 where is NM listed?

Bump...

220.49? I don't see that in 05 or 08

Maybe Mike meant Table 220.42 ??

In 310.16 where is NM listed?

Cable types aren't listed, only wire sizes. See 334.80 which says to use the 60C columns in 310.16 for NM to select wire ampacity. (In other words size NM the same as TW, UF.)