I consulted with a licensed electrician, and he did not believe me that the unused 240 volt wire from the panel to the cooktop did not have a ground wire on it. It is an 8/3 wire, 8 gauge and three wires with no ground. This had powered an all electric Jen-Air Cook top that was installed in 1980. It became useless after we remodeled the kitchen a few years ago and went to all gas. The red and black wire were connected to the double breaker on the panel, and the white wire was connected to the bus bar. I believe code changed in the 1990s that specified a 4 wire over this 3 wire (additional ground wire).
I was told per current code I had to have a ground wire run from the main panel to any subpanel I would install, and per code I could not just connect to a water pipe, which I would not want to do anyways. So as that stood, I was looking at hiring someone to either run a ground or replace the wire of the old 8/3 wire, and that would involve cutting drywall, etc.
I had also decided in the meantime that I was only going to go with a 1 HP chiller, so the need for a 240 volt source disappeared, but I still needed a dedicated 20 amp circuit. So what the Electrician suggested was that I convert the 8/3 wired double breaker to a standard 120 breaker at the panel, and use the red wire as the ground, and then just wire in regular Nomex from a junction box to the new receptacle.
So I used the existing box where I had the 8/3 wire capped off in the basement, and wired Nomex to the 8/3, taped the red wire ends with green electrical tape to signify it being the ground, and ran the new wire and installed the new receptacle for the chiller. Then at the main panel, I removed the double breaker, connected the new 20 amp 120 volt breaker to the black wire, and connected the neutral (white) and the now green wrapped red wire (neutral) to the bus bar. I also capped off the empty slot in the panel where the other half of the old double breaker used to be.
I confirmed the wiring was correct at the receptacle, and so now I am all set with a dedicated 20 amp circuit for when my new 1 HP chiller gets here. I didn't have to have any new wiring run, and I was able to re-use old wiring without tearing up the drywall around the panel.
