Also, if all is ok in the electrical world, then why is it that it is MANDATORY for the refuel truck to be grounded to an earthing point AND the aircraft..... static discharge perhaps?
Yes, age old practice to ground or "earth" both the truck and the aircraft. To to say we do not encounter fuel leaks today but they are less that they were years ago. Also to mention The high flash point of jet fuel as opposed to 100LL when the practice was initiated.
EWIS, here is an outline (the FAA take on it)..
It was a knee jerk reaction to TWA flight 800. Routing, terminating and protecting of wires especially in a fuel tank is taken much more seriously. Fuel pump C/B's do not get reset w/o isolating a fault first. Fuel tank inerting has become common in the civilian world.
The only rule that ever made sense to me was keying up an HF on a 74C as the couplers are out on the wing tips close to the vent boxes. WXR that is contained in the front of the aircraft and is much lower wattage with flat panel systems or nav/high intensity lights out on a wing tip that have been maintained and designed to higher standards would not make me think twice about turning on. Every aircraft I have ever been around in the last 20 years has had nav lights burning during refuel.
May it be that earthing is not as safe as grounding
, I think not.