Why does my 2017 iMac work in every building except my office building? I moved my iMac from home into my office and it would not turn on at all there. So I took it around the corner to a repair man and it turned on straight away at his shop. He suggested I get a UPS to see if that makes a difference. So I took it back to my office and tried plugging it into a UPS, but it still did not work. The input / output voltage on the UPS display read 245 volts (I am in Australia where the wall sockets should be somewhere in the range of 230-240V).  I figured that the voltage must be too high for the iMac, since the power at home (where it works fine) is 230-240V as it should be.  So I unplugged the UPS from the wall to run off the battery and the UPS started outputting 230V yet still the iMac wont turn on!

There has to be something wrong with my office building because the iMac works fine everywhere else! Is there anything specific to the iMac power supply that could cause this?
You can plug the Mac into any voltage from 100 - 240v &amp; it will not care at all, so that's a red herring. 

I'd suggest a mains socket tester plug, to ensure the socket is correctly wired, from the wall &amp; also the UPS.
Also, skip the UPS &amp; test the Mac directly in the wall too. That would be the most probable fail point.