Why is my new doorbell transformer hot or overheating. The new transformers is a variable type. It has three wires, one black, one white and one green. I connected it color for color simple right!!! After hooking it up, I also tested it for proper operating voltages, and it tested ok it ranged from 10v to 26v. The doorbell button and chime are disconnected I don't get it. I did mine at my house and everything went smoothly. Please help!!!