The latest mains socket testers as well as verifying correct socket wiring (28 different fault conditions) also incorporate an rcd test and non-trip earh loop impedance test. Around £55 per unit over here.
XTRXTR :
"There was no ground. That switch you talk about may have been called a ground switch but that is a misnomer. With only a line and neutral power cord the cap is between line and neutral if flipped to the line side. Neutral is chassis. Depending on which specific Fender layout the cap is...
GFI is called RCD (residual current device) over here in the UK. If you're using an electrician's screwdriver ( not recommended as you are part of the circuit btw) then make sure it's dry. Well, that's obvious, you say but the apocryphal tale over here is the story of the electrician's mate who...
"Fender put a Cap between Line (hot) and Neutral.."
Not so, the cap is connected between the ground switch and chassis. The switch connects the other end of the cap to either line (hot) or neutral.
If it was connected across line and neutral it would blow the fuse if it went short, also it...