Size sub panel for each apartment in a 3 family house

fotostatNovember 18, 2009

In a 3 family house there are three main panels in the basement, one for each apartment. Some circuits are taken out of those panels, but there is also a sub panel inside of each apartment that the rest of the circuits are taken out of.

Is there any calculation that needs to be done to determine the size of that sub panel?

Right now the panels are fed with a 12-2 (that's right, single leg) and there has never been a problem.

The panels need to be upgraded, would it be alright to refeed them with 10-3, which should be more than enough ampacity for them? Or should it be bumped up to 8-3 just to be safe?

Thank you for reporting this comment. Undo

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.

    Bookmark   November 18, 2009 at 11:52AM
Thank you for reporting this comment. Undo

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.

    Bookmark   November 18, 2009 at 12:29PM
Thank you for reporting this comment. Undo

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!

    Bookmark   November 18, 2009 at 2:31PM
Thank you for reporting this comment. Undo

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

In 310.16 where is NM listed?

    Bookmark   November 18, 2009 at 10:09PM
Thank you for reporting this comment. Undo


    Bookmark   November 22, 2009 at 8:53PM
Thank you for reporting this comment. Undo

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.)

    Bookmark   November 23, 2009 at 5:33AM
Sign Up to comment
More Discussions
Troubleshooting Kohler 12RES Problem
I have a Kohler 12RES generator with an RDT 100 Amp...
1 of 2 security light bulbs keep going out, do i need a new light?
I have a security light fixture in my carport that...
Bath fan/light combo
Attached is wiring diagram of masterbath (I hope I...
Garage florescent light flickering - bulb or fixture problem?
I replaced the GE F40 RES garage lights with a GE F40...
bibbus 7b
Power to shed
Looking to run one 20 amp circuit to my shed and I'm...
Sponsored Products
Silk 20-inch Mini Calla Lily Flower Arrangement
Copper Pet Feeder with Iron Stand - Small (5"H)
$259.00 | FRONTGATE
Luxury European Toilets
54" Muse Chrome Ceiling Fan
Lamps Plus
Wakefield Small Textured Black Outdoor Wall-Mounted Lantern
$134.00 | Bellacor
MaxLite MLFP22EP3650 Edge Lit LED Flat Panel, 5000K
KOHLER Bathroom Lighting Polished Chrome Recessed Shower Light K-1665-CP
Home Depot
Bocci | 21.3 Three Pendant Chandelier
$885.00 | YLighting
People viewed this after searching for:
© 2015 Houzz Inc. Houzz® The new way to design your home™