Hey, I do a lot of physical cabling, so I can chime in on this too. I always try to keep electrical and cat6 as separate as possible, if you are doing cabling for a new building, cat6 should be in its own trunks anyways. Thats not always realistic when you are running additional cables though. Just do your best to keep them away from each other and you wont run into any problems. If the electrical is that metal shielded stuff you don't need to worry much at all. Also, when crossing a cat6 cable over electrical, try to keep it as close to a right angle as you can, that will also minimize interference.
Edit: Just to add to this, you'll only really run into a big problem if you are zip tying a cable to electrical over a long distance. You can probably get away with more that you think you can, unless you are dealing with crazy voltages, or strict regulations.