Adding a wallmounted TV in my basement, I wanted to run power from an
existing outlet 3' below where the TV will be. I have the holes cut
and the Romex run, but the original receptacle is fed by AC cable into
a metal box (obviously). 4 conductors total, with a receptacle and one
clamp. If I feed power to the new TV outlet, that will be another 2
conductors and another clamp.

So basically what size box is now recommended (required?), for 6
conductors, 2 clamps, and a receptacle? I found something on Racos
site that pointed at 22.5 cu in required, but I wasnt absolutely sure
about their chart

Thanks in advance!
-Chris