"What does this wall switch with circle dial and fuse do? Found in 1950s house."
A: "I have something similar in my house built in the 1950’s and the dial would select the circuit and the button on the bottom would turn the circuit on and off. In my case it could comtrol 80% of the lights in my house. They took the wiring down from 110-120v to 24v and used tones of small wires. You probably have some relay boxes in a closet somewhere unless the house was rewired."