Had the same problem with our cabinet at work. Took a large diameter wire attached it to a bolt on the outside of cabinet. Then ran it down to the concrete slab with a weight on it to ground the cabinet. Seemed to work OK also put a large rubber mat under the standing area as well.
Since I was the shop manager I didn't tell others about this. People would come in blast stuff with oil & gunk on it screw up the beads. In other words abuse all the shop tools never clean up or maintain etc. So I would watch the guys using the blaster getting shocked and enjoy ;D