100529-1445 EST
Riograndeelectric:
You are listed as a Master Electrician and that means you have considerable experience. So the following should be easy.
There is a very inexpensive instrument that is moderately accurate that measures voltage over a limited range from about 95 to 135 V. All of the measurements that this instrument can make are dependent upon the voltage being within this approximate range because there is no other source of power for the instrument.
It can measure voltage, current, VA, power, PF, frequency, KWH, hours. The basic "KILL_A_WATT" device can be had for about $25. The same thing but with EZ added to the name has been available in Costco stores for less than $30. On line search shows neither model at Costco.
The EZ is less easy to use, but has the advantage if you want to run experiments on long cycle time things, like refrigerators, then your cumulative KWH are not lost on momentary power loss.
Buy one of these. Take it to where the demonstration is. Put it in Watt mode and have the demonstration run with this monitoring power. You do not need to use the KWH mode to prove that the PF device (capacitor) is a fraud used in a home as advertized
.