Ed:
Thanks for the information. I have only seen a few of these split bus panels. Regrettably, most of the ones I've seen had been altered by Harry Homeowner, who didn't understand (or care about) the six-throw rule. The main (top) section had the two 240 v. disconnects for the lower sections, but the rest of the main section was filled with single and tandem breakers. I remember one such panel that actually required 14 throws to turn off everything in the residence - no main disco at the meter, of course.

Mike (mamills)