I installed a new GFI outlet in our bathroom for our new electric toilet. To do this I cut wires to the exhaust fan and added new wires to the new outlet. The three wires, from the breaker, to the exhaust fan, to the new outlet, were joined together with wire nuts. #12 gage wire. When all the functions on the new toilet did not work, I called the manufacturer. He told me to try a hair dryer in the new outlet and sure enough it did not work. A device with a light load, a small fan, works fine. Interesting if I turn on the exhaust fan, the fan turns off. Also, the new GFI outlet reads 120V but zero if the exhaust fan is on. I am going to have to tear the wall apart after having painstakingly repaired it. I don't quite understand all this.