Thanks for your input, nickdel... and 220/221. It's hard to descibe the configuration. I'll just say that the original owners of my house took a roundabout route in order to conceal the cable without taking down the ceiling. I've taken down the ceiling and located a perfect "chase" that will allow me to take a shorter route, thus giving me the extra I need for a splice. There's even room for the 6x6x4 j box. I understand your point about creating a weak point and potential point of failure. Unfortunatly, notching my joists gives me a similar concern. The cable alone would only require a notch of an inch or so, but it's in conduit. The notch would need to be 1 3/4 inches... pushing the limits on notching a 2x10...
I can't pull the cable out of the conduit without either cutting it or disconnecting from the panel. If I disconnect from the panel, I have to tear out the ceiling of a large, finished part of my basement that I didn't plan to touch... so is the weak point in the cable really that big a deal? I don't want to burn my house down, but I also don't want to tear out a 30 foot length of perfectly good, finished ceiling...