Re: Ground Loop?
Ground loops occur when there is more than one ground connection path between any two points in your guitar wiring.
The most common ground loops found in guitars are where the pots cases are connected by a ground cable and also by the shielding of the electronics cavity. If the shielding is conductive (copper, aluminium, steel etc etc) then ground connections between pots produce ground loops.
When you have multiple ground paths pot to pot and to the ground on the output jack they act like an antenna antenna which very efficiently picks up interference. Because of the innate resitance differences between the different ground loops you end up inducing mini currents in the ground system and outputting those mini currents as noise in your signal.
Just remember there should never be more than one connection to ground for any idividual bit of kit (pot, switch, trem-claw etc)
hope this helps