Exactly 10 years ago, i was doing an engineering internship in a News Paper factory.
They had problems with the power company unexpectedly dropping a phase and then deny it. Obviously all heavy equipment (read: Printing Press) stopped working.
I volunteered to solve the problem, with a PIC obviously.
This was my first REAL WORLD project.. MANY mistakes where made, and Much safety requirements where COMPLETELY ignored... I am surprised i did not die.
The project was to sample all 3 incoming 480VAC lines, in the transformer room outside, and report it to a PC on the 3 floor, wirelessly, with sufficient detail to graph the 3 phases to see and record evidence against the power company.
Wireless options where not as easy or varied as now, so i made my own radio transmitter from discrete components, and receiver using 433MHz radio module.
The 480VAC lines were read using the ADC, but stepped down using a resistive voltage divider and conected to the Power lines using alligator clips!