OK, a little more info:
- taking a voltage reading between the two circuits in question, I get 245V. According to another resource, this means the circuits are on opposite phases, and I shouldn't have a problem with the shared neutral. Is this correct?
Now, looking at the existing neutral/ground bus on the 20-space main panel:
- there are only 16 or 17 locators. How the heck is a guy supposed to have enough spaces on the bar to accomodate 20 circuits? Even if only 1/4 of the breakers have shared neutrals, that's still 15 inidividual spaces needed for neutral landings. That leaves 1 or 2 for ALL the ground wires? This just doesn't seem right.
Looking more closely at the ground/neutral bar reveals there are smaller holes right beneath the regular holes for securing the neutral wires. But, as far as I can tell, there is no way to secure a ground wire in these smaller holes. What are these for? I might have to snap a picture to reveal what I'm talking about here...if this is too confusing.
Thanks for the help.