Re: AC and signal cable of whatever type
To form a real tranformer, the current has to flow one side, in this case all pairs have a differential current of zero, at least that should be. So not a transformer. That is the nice thing with differential / balanced connections.
However all sorts of other things can happen (coupling between cables is one), so I wouldn't advice to have large reels either!
I know lot of people won't agree with me, sorry, I don't want to start that discussion in this thread. Back in the days with unbalanced connections, one would have a point for sure.
