On September 8, 2017 at 15:49, lippavisual said...
Usually, it's because the outlets powering your racks are on different phases of power within the electrical panel. If that's the case, the electrician should be able to move the one breaker so they share the same phase.
But, it could also be cable company not grounding their service at entry to the home/building. Are these at play too??
Run a long extension cable through the house and connect the 2nd rack to the same outlet as the first rack. If the hum goes away it's a power phase issue. So moving the breaker to the same phase should fix the issue.
In the future, I suggest not having two racks. If it's an absolute must, you should be using fiber to connect the two.
