You arrive at a venue to do a gig only to find that the Circuit Outlet designated for your use has an Open Ground. There is no other place nearby where you can plug in or run an Extension Cord. There is no qualified personnel present to remedy the situation. What course of action do you take?
I had the same problem working as an audio engineer overseas in Europe and Japan. To be prepared for open ground problems I made plugs with the hot and neutral prongs missing with only the ground pin intact. Then connected the plugs to a long 10 gauge wire in each end, only with a ground prong. I would then connect the first end in the power strip that's connected to the outlet with the open ground and the other end to a circuit that has a good ground on the same circuit. Because there's no prongs for the hot and neutral the only thing that's connected to the circuit is the ground. By doing this it's a emergency fix for an outlet with the open ground. It is very important to make sure to use a circuit on the same phase to avoid ground loops. I would also take it a step further and wire up some plugs with the hot and neutral reversed in case I had a problem with reverse polarity.
I also had a grounding cable reel with a grounding rod at every job site.
Hope this helps you, good luck!