I have a 200 amp service in the house. I've sourced a 150 amp breaker that will work with my main panel (the plan is to used a main lug sub).
As already pointed out, assuming a detached structure and more than six branch breakers in the sub-panel, you WILL need to have a "Local Disconnect". The easiest way to do that is to use a Main Breaker Panel. The (not-really)"Main" breaker in the sub panel needs to be rated for AT LEAST as much current as the branch breaker in the main panel which is actually protecting the feeder cable; in your case, 200A would be fine.
The run is less than 100ft but I'm limited to the current conduit size for the existing 50amp service. The good news is that the conduit is 1 1/2" which is the proper size for a max fill of 4 1/0 wires which is what is required for the 150 amp sub panel.
You're obviously assuming copper wire, as opposed to aluminum. That will work, provided it fits on that 150A branch breaker you found; and at "less than 100ft" voltage drop won't be a problem. But man, it is going to
CO$T!
Now heres my question. I can't seem to find 1/0 3 conductor copper wire anywhere. Am I missing something or are things done differently once you get to that size wire?
You'll probably need to use separate pulls of THWN:
http://www.southwire.com/products/THHNTHWNTWN75T90OEM.htm
http://www.homedepot.com/p/Southwire-500-ft-1-0-Stranded-THHN-Wire-Black-20505402/202316221
Buying a 500-foot spool might seem like expensive overkill; but in the long run, it may well be cheaper than buying ~300 feet "by the foot".
Note that since you will be using the same (black) wire for all three main conductors, there are marking requirements in the NEC which must be adhered to.
Looks like I need to go to an electrical supply shop instead of just a box store? I hate living in the middle of Amish Ohio.
Great info on needing a main breaker in a detached structure! The Siemens panel I have lists- " Ratings: 200A Maximum - See Main Breaker Rating if Used", so it appears I'm fine using the 150a breaker.
I could be wrong; but
MY interpretation of that would be that it is the PANEL ITSELF which is rated for 200A Max, unless a lower value is imposed by the installed main breaker. That is separate and distinct from (and thus does not address) any more-restrictive limitations on individual branch breakers.
If I could get away with a 75a run I would but the powder coating setup i'll be running requires more power than that. The Commercial grade oven I'm looking to get is probably going to be close to maxing that out by itself.
IF you can get by with a 90A feed, the 2-2-2-4 MHF will still work, and save you a ton of money. I have no idea why "theoldwizard1" suggested a 75A breaker.
