SecretSquirrel wrote:Mutual inductance between the two cables will impart a low power voltage of equal amplitude to the HV cable. The two cables are effectively a 1:1 air core transformer. In most cases the power is so low as to not be a problem as the efficiency at 50/60Hz is very bad and twisted cables are designed for currents to cancel, etc. However, just because its probably ok, most of the time, doesn't mean there aren't plenty of ways for someone to make a mistake that is costly.
Last time I was involved in a data center, our design rules forbid HV wiring from even sharing the same cable tray, even when run in conduit.
Induced voltage is a function of current, proximity, and parallel length. If the power cables in the vicinity aren't running dozens or hundreds of amps, a few feet of parallel distance and single-point shield grounding are likely adequate at the required 300' run for the data cable to function safely and correctly, provided local code otherwise permits the installation. A datacenter is an entirely different scale of animal -- you're distributing literally megawatts of power and any copper data transfer is running at very sensitive GigE+ speeds.
That being said, if the OP can pick up the range-extender with a laptop outside the outbuilding, then he just needs a simple WiFi bridge at that same outbuilding, with an outdoor extension antenna. The rest is apparently there and working.
