Re: More than once
That's reminded me of another one. ACT Apricot had their own networking system which was point-to-point two wire cable. A customer had a new office building in progress and I asked to be able to speak to the person doing the wiring so we could ensure it was correctly installed. I was basically told I was being presumptuous as "they know what they're doing" but reluctantly they agreed to a site meeting, which turned out to be with the site manager, not a sparky.
Of course the wiring was incorrectly installed as a ring (zero information being passed on to the man actually doing the job), fortunately leaving the two ends joined at an accessible socket so I could disconnect and insert the required termination resistors, which had also been omitted, at each end.
They'd also paid a fortune for turned-earth-pin sockets for the computers (so nothing else could be plugged in), to be connected to a separate phase to everything else, as the systems were vulnerable to power issues and in particular didn't like computers on the same network segment being on different phases. The architect had ignored the fact there's a minimum phase-phase physical separation mandated and had put the special sockets right next to the normal ones, so the sparkies had wired everything up as usual, all upstairs on one phase and downstairs on another. The spend got even worse when it was discovered they hadn't provided any plugs for the special sockets and a motorcycle courier had to be used to get some urgently! Had we been aware of what was happening, and been able to pass the info on, we'd have simply put two network segments in with an opto-isolator between to eliminate any ground loop issues.