ECN Forum Forums Safety Discussion and News Occupational Safety Discussion You aren't going to believe this!

I assume they have a warning somewhere that you should ensure that the UPS and the PC are on the same phase.
In real life that may really be all this magic box is. Just a N/C closed relay that picks if the two cords are not in phase preventing switchover, an OK light and a switch. Relay optional. It could just be a 'not ok' light and a be careful sticker.