I do mostly design of emergency power of large facilities and have only been doing that for 8 months; did electronics work before that- I'm learning quickly, but there are engineering issues, and there are nuts and bolts issues, and I'm really out of my element on this one [Linked Image]
http://www.sea.siemens.com/speedfax05/05%20Speedfax/05Speedfax_01/01_27.pdf

It's a 200A "Ultimate Load Center", which will be a 125A branch circuit off a 200A main panel. It will be located in the addition, about 40' from the main panel. Is MLO legal? I'd assumed I needed a local disconnect, but that might be a MIL-SPEC requirement specifically for servicible electronic equipment, now that I think about it... If MLO is OK, shoot, I'll just do that! Where in NEC would the relavant code be, I'm having trouble fining it? If MLO isn't legal in this case, I'll call siemens and see what I can do. It looks like the plate is replaceable, so maybe I can just get the right one for not a whole lot of money.

MBK125A is the breaker I wanted, and it's specifically stated on the label on the inside of the door that it's the right breaker. The one I bought at the big box for $50, the only main breaker for these panels they sell (MBK200) does fit on the bus, it just doesn't fit the panel front. Siemens has the exact same breaker listed for $473 in their catalog. I really intend to use it soley as a disconnect, and use a 125A breaker in the main panel as the overcurrent protection

[This message has been edited by SteveFehr (edited 07-19-2006).]