I like putting the TC's as close as I can to my computer, modem and other sensitive electronics
I actually accidentally ran a small TC sitting ontop of my netbook once, still works fine, except it messed up the graphics temporarily and I think it also killed the battery management inside the battery. Oh well, the computer itself still works fine
For the longest while I was afraid to have my laptop on while running any HV or RF device but I eventually got brave and unplugged the laptop (so it stayed floating in reference to ground) and ran at low power. No ill effects even at 2kW output power. The distance is needed though as at even 500W power output any object within 5ft will see more than 1kV AC on it in reference to ground. In fact a ground reference is not even needed as two floating objects at different radii will see a voltage differential between themselves relative to their distance from the RF origin.