The frog eye as it is called around here only alloys connection to the 115/120 outlet. As does the volt meter. If you only require 115/120 volts this will work as allowing you to check for open neutrals crossed wires no ground and voltage ect. It will not prove anything on a 240 volt 50 amp outlet. If this is what you have you would be better off with a decent vom and learn how to use it. STILL things happen but at least you can find out if anything is suspect before you plug in. Progressive units are cheap insurance in my opinion. Larry