Re: capacitor's
Considering the fact that he has now stated most of his problem is coming from a couple of fairly large motors, we all seem to agree the best bet is to wire in some PFC caps in parallel with those motors so they switch on only when those motors come on.
It is indeed possible to get some I^2R losses if you install the PFC caps a long distance from the actual loads, but that is a different issue. If the only thing the plant cares about is correcting their PF problem so the utility gets off their case, a central cap bank may make sense. I think it is a less then ideal solution, but in most cases, it's not going to overload anything. I suppose you could come up with some scenario where it would, but it is unlikely.
It would make some sense to get the PFC bank as clsoe to the load as possible when they do install it, since it probably adds no cost and will reduce I^2R losses somewhat, but this kind of thing will more likely be dictated by available space rather than the few bucks a week of electricity you might save.