Neville/Mike,
That's an excellent description/supplement to my basic understanding of the phase offset in my circuit breaker panel. I pulled off the cover and took a look at the two blank blank spots where the new double pole breakers are going to go. Now that I know a bit more about what I'm looking at, I can see two "power busses" (probably the wrong term) that zig-zag or alternate their way vertically up the back of the panel. So as you described, when I plug in a double pole breaker, I'll get a connection onto each of those busses - now I know that those 120V legs are 180 degrees offset by virtue of how the breakers clip in. Wow, I buy a ShopBot and get an improved education in household wiring as a side effect. Now all I have to do is put my tongue on both legs at the same time to verify the phase offset.... (VERY bad joke!!).
Everything else mentioned has already been implemented - breakers sized to protect the wiring gauge and wiring sized to handle the amperage loads.
David, regarding the actual need for a fused disconnect, my bot will temporarily live in a location that is not within sight of the breaker panel, so some kind of disconnect was needed. It was less expensive to put in a fused disconnect box ($14 for box and fuses) than to purchase a 30A four-wire plug and receptacle. Plus, I'm "officially" following the instructions in the ShopBot manual (which stipulates the fused disconnect), though all the previous comments which mention why you wouldn't necessarily need to do it that way are perfectly logical. The redundant fuses as a possible source of problems is something I'll definitely keep in mind.
Thanks again to everyone that has chimed in on this topic - hopefully this thread will add to the ever growing knowledge base on the SB forum.
John
