In the December 14 issue of EC&M on page 32 under "stumped by the code" Mike is quoted as saying "some circuit breakers rated 30A or less can have two conductors under each lug". I can't count the number of times a home inspector has conditioned a report as violating code by having multiple taps on a breaker. What is the reference for this being acceptable?
It depends on whether it is listed that way.
Not all of them are, so I think the AHJs hedge their bets by saying no, but if you can show them that it IS, then they should except it.
So for instance Sq. D is, as mentioned above, so is C-H, but ONLY the type CH breakers, not the BRs. No for GE, no for Siemens / Murray either. I suggest that if you have to do it, then make a copy of the data sheet / catalog page that shows that the breakers are UL listed for 2 wires per lug, and have it ready to show to the inspector. Or if you are not there for the inspection, tack it next to the panel and highlight that info.
You also can't mix the type/size of wire that is installed on that listed breaker. I assume it is because you would get uneven pressure on the two conductors if you mixed them.
On the Cutler Hammer CH breakers, they specifically say you can mix solid and stranded together, no mention of mixed sizes or restriction thereof though, it just says (2) #14-#10.