The data center I work in has 415 VAC power coming in to each rack, with three phases and a neutral. Equipment gets a phase and a neutral, for 240 VAC (though not in a configuration you’d normally expect).

It’s important to remember that everything is contained in equipment made by companies that I trust (Rittal and Eaton and APC). Also, everything is grounded (the doors to the racks, the racks to the cable ladder, and the cable ladder to a special ground), which is in addition to the equipment ground. Finally, I know (and work with) the people who build and maintain the infrastructure.

As for the thick cable, if you’re up to it, here’s a video showing a process for joining the cables together: https://youtu.be/EvWx-VKVvmo

The thing to note, is the layers of copper ground that are wrapped around each conductor line, as well as the bundle itself.