I have been using my portable with the standard supplied probes for about a year now on Arduino and Teensy projects.? I live in a motorhome and recently have seen power problems with the 120VAC power supplied by various parks.? What would be the safest way to input the line voltage to the scope to display the wave form with the portable?

I believe a small 120V/12V transformer will be the best. Provide isolation and safe low input voltage.