Running Equipment

I'm having some problems at the ground between some units of measurement and control PC. Talking with their tech support, they asked me "Is this the computer that is running on the same stage of the distribution network as a power tool that turns blue phase meter? I am still a novice with electricity and I wondering how I go about answering this question. Do I connect to both an oscilloscope and see if they are in phase?

oscilloscope is certainly the way forward
phase simply means that the two AC signals will peak and valley with each other
they should be on the same frequency able to be consistent

Well, if it's AC 110-120V, then a son is hot and the other neutral, and the DC voltage is pos and neg, you can verify this with an engine of toys to see how it runs, it will reverse when the polarity is changed

With an AC voltmeter stick a probe in the same location of each shot. If you read zero volts they are in phase. If you read 220, they are in opposite phase.