There's something that seems obvious to me that I never see mentioned on these threads. Square D makes a mechanical interlock for their QO panels that allows you to interlock the normal main breaker with second, back-fed main breaker in the upper right-hand location. The interlock assures that only one of the mains can be "on" at any time. (Both can be "off," however.)
I understand that this is UL listed for feeding a generator into the panel.
This appears to be the obvious way to go--a few bucks for the interlock (I think it's $10-$20), one breaker, and you're good to go.
So why aren't people doing this? Is there some problem with this approach that I'm not seeing?
