Yancey Slide: yes, ditto. Only, UPSs have a habit of being interruptible, and backup generators have a habit of not starting, unless they’re regularly exercised. Equipment that’s only used in emergency is really hard to keep on top availability.
A useful scheme is to have two mains power supplies, from different stations and networks, fed onto the site in different places. That last bit is important: at one site where I worked we thought we’d done everything right, only to find that the contractor had run the two supplies in the same conduit, a foot apart, so that inevitably it came to pass that some fool with a backhoe dug through both at once ..,