I moved into a new house and was working on making a three way switch work properly when I came across some creative wiring. The traveling wire between the switches was only two wires, and the ground from it had been electric taped over and used as a neutral wire for the lightbulb.
Obviously normally this would be very dangerous because you wouldn't have ground wire in case of short circuit, however, there is an outlet by one switch and another switch by the other. The grounds from the wires for those has been used as the ground for the switch. That outlet and light are on the same breaker. Here's a rough diagram of how things are wired:
What are the risks as a setup like this? As far as I can tell, everything is grounded and should be okay but I'm no electrician.
Edit: I was using the word "drain" instead of "neutral" and fixed it.