I installed a ceiling fan and do want to NOT have a dimmer light style switch due to lots of humming in the wiring. I am confused as I have two black wires to contend with and the white wires are tied together. The new switch just has three screws, I assume white, black and ground. I am confused which one of the black and white wires to use or use both?

OK guy’s let see if you can help me figure this out. This is at my cabin. It was wired by original builder about 30 years ago. But all the light switches and plugs are not installed. I was ready to add a switch to the wires in picture # 3. Assuming one line was hot and the other went to the light above sink (not shown). However after stripping the wires and turning on power neither of these cable had power. So we assumed one of the other outlets or switch boxes must have a non connected cable. Just by luck we open the kitchen light switch box (since it was closest to the bathroom switch box) and lo and behold another non connect cable is right there. This seemed easy. Pigtail the kitchen light switch (#1) off the power line feeding the switch and connect the adjacent cable and then power the bathroom light. NOT! When power was applied, the bathroom cables had still had no power. BUT…if the kitchen light switch was turned off. The bathroom (#3) cable to the right has power. No power to the cable on the left. I’m pretty sure the cable to the left goes to the light fixture, but I did not try it. My friend and I tried various combinations but could not maintain power to the switch box in bathroom (pic #3). Somehow the person who wired this used both black and white as power feeds. This combination of wiring is beyond my understanding. The pictures hopefully will explain my dilemma. Right now as the pictures show the switch in picture #1 operates the kitchen light as can be seen in picture #2. Take your time in responding if you understand what’s going on. It will be at least another week before I can get back to the cabin. Maybe two. Other than unfolding cables from the fixtures it is exactly as we started. We changed nothing. I don’t understand why this was not wired in the usual black to black and neutral to neutral. But I believe the original owner knew what he was doing and followed codes of the time period. It will be near impossible to remove wall surfaces and it will be a real job to try and fish new cable through the walls. If worse comes to worse I may have to use external wire ways.