I have dogs, cats, little kids, lots of chickens, and me stumbling around in the dark.  We all get zapped once in a while.  Coyotes and foxes, plus other critters respect the fence. 
What the bad guys really respect is being in a situation where they try to scale or dig through / under something and keep getting zapped.  They get frustrated and leave.
Best place for me to protect penned chickens is to place their pen right next to the electric fence.  The predators have trouble focusing on getting a chicken out when there is risk of brushing up against the hotwire.