Is it safe to use the ground as a neutral when other grounds are available?

Question

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.

Answer 1

What could possibly go wrong?

• If the ground wire is bare copper, you massively increased the risk of a ground fault, which can kill somebody or burn the house down.
• If the ground wire has a smaller cross-section, it will not be protected by the breaker from overheating and can burn the house down.
• Somebody working on the system may falsely believe the ground wire is, in fact, ground. Neutral wires are just as dangerous as live wires (e.g., a loose neutral may unexpectedly become hot if any appliance on the circuit is switched on). This can kill somebody.
• Somebody may 'fix' the ground by tying it to ground, creating a electrocution hazard long after the 'fix' has been made. This can kill somebody.

In my attic, I found a junction box where the owner had made sure their setup was 'safe': they connected an insulated 2.5mm² wire to another insulated 2.5mm² wire. Only, one was brown and one was green/yellow. Perhaps they decided to 'safely' ground an unused live wire? Or used a bit of leftover brown wire to ground the ceiling lamp? If I hadn't found this box and instead repurposed the other end of either cable, I may have killed somebody (or myself) or burnt the house down. I'm sure the previous owner did not realize that.

Answer 2

You have ground being used as neutral. That is a serious code violation and can cause a number of dangerous problems.

In the old days, the only real solution would be to run a new cable. Fortunately, today we have smart switches to the rescue! Look for a smart switch that has 3-way operation but that only needs one traveler between the switches. That can be by using some sort of signaling over the power line or by one the switches being a wireless remote.

Make sure to get something that is properly UL or ETL listed - generally that means either knowing exactly what you want (specific manufacturer/model) or by shopping at a traditional bricks and mortar store such as Home Depot or Lowes (shopping online is OK, as long as the items are sold in the US stores they will be properly certified) and not an exclusively online retailer where the items may be provided by a 3rd-party and of dubious quality and safety.

Answer 3

I'm assuming by drain, you mean neutral. Ground wires can not be used as any other conductor, repurposed. If its green insulated or bare copper, then it must be used as a ground and only as a ground.