Yes!
Even with cable going through plywood with a notch, the plywood adds lots of strength due to the cross grain and increased joist width. It strengthens what may be a possible stress riser(weak point at which forces become concentrated.) Try to deflect plywood on edge - it ain't easy. Thats why it makes great box beams. I had to do this under a kitchen remodel(my old house). I just cut 1/2" plywood the depth of the joists, three feet long and glued and screwed it to one side. Two would probably have been better, 4 feet long would have been nicer, but I am "frugal"(the plywood was in the scrap pile) and lazy...
Len
[This message has been edited by Len_B (edited 02-12-2003).]
