If you're mounting above an outlet, then the wires could run along the edge of a stud. In that case, if you hit the electrical, you did a bad job of mounting the TV mount.

Or, they will drill holes through the middle of studs to feed the electrical horizontally. Typically from outlet to outlet (no worries there since you aren't mounting the TV that low). Or from switch to outlet (on the same wall, it would typically go down to outlet level and then horizontal).

So, if you can determine the center of a stud and drill a hole in the center, it's not likely that you're going to hit electrical. Now, there's a chance that a crazy person did something other than stated above (I've experienced it) and hopefully they put a metal plate on the stud so that you can't accidentally drill into it.