So I have had the compressor plugged into the wall outlet (no transformer) for a few weeks now. Has run just fine. This morning I could hear the pump struggling a little so I shut it off immediately. Checked everything and actually determined that I hadn't changed the oil for 2.5 years when a once per year change is called for. Changed that and plugged it in and it ran fine for the most part though there were times when it start up to fill, running strong, then lose a little steam for 20 seconds, then catch it's breath and be back to normal. It wasn't so much that I was overly concerned but you could hear the change in tone of the pump during this cycle. Didn't happen all the time.
That prompted me to send an email to Eversource. Two story commercial building, I have the second floor. I asked if I had single or three phase. The engineer's response was:
There is both 1ph, 120/240V and 3ph, 240V delta going to that building. You would need to contact your electrician to find out about your breaker box or other private property equipment.
I asked if they knew which went to which floor and they said they didn't.
My floor has roof mounted HVAC to cool or heat the entire floor, about 4000 sqft. About 15 years ago I had a professional electrician disconnect that and wire in a silk screen dryer to that circuit. The dryer could be used 230V-single or 230V-3ph. The compressor outlet, shown below, was for a 5000 watt metal halide bulb used for exposing silk screens.
The industrial space below me has no major electrical requirements except for an industrial size Hot Dawg natural gas heater to heat their space.
Not sure if either of those provide clues as to what I have.
I did run these tests with a Fluke meter if that helps in determining what I have.
And my friend came down with his Fluke Scopemeter that we connected to a dryer extension plugged into the compressor outlet.
Any thoughts?