If it helps the this light switch turns on two seperate ceiling lights in the bedroom. A three way switch is different.
Video On How To Wire A Three Way Switch
3 black wires light switch. Its essential that you determine which black wire is hot before proceeding. Hook the white wire to the top terminal on the switch. While a single black wire is pigtailed and connected to the bottom screw non green screw. Two black wires are going directly into the quick connects. This type of switch has two brass screws usually on the bottom and a copper or black screw on the top left. Hook the bare wire to the box and to the switch.
The standard way to power a split tab outlet is to run a three conductor cable to a wall switch. There are groves on a plate under the screws. This type of switch lets you turn the light off or on from more than one place in the room. Another black is in a loop around bottom screw and 3rd screw is in hole next to bottom screw. Only 1 of the black wires seem to be hot lights up the voltage tester when touching the 3 whites and one black together. The ground wire also connects to the switch but the white wire gets spliced to the circuit neutral wire and bypasses the switch.
I have single pole light switch with 3 black wires. When opening the switch i found 3 unmarked black wires as shown here. Steps for wiring a 3 way light switch. However if you need to rewire a light switch or a plug socket you may occasionally come across two black wires. When i put all 3 black together and all3 white together the light works as long as the switch is in the off position. I have 3 white wires and 3 black wires in a light fixture.
The easiest and safest way is to use a multimeter to test for current. Turn on the power and test the switch. The new switch has a different way to attach. Hook the black wire to the bottom terminal on the switch. Im not sure how to reattach. The other two black wires trigger no response.
The cable has a black wire which connects directly to the circuit and a red wire which connects to the switch. Ideally the old switch is still there so you can wire the new one up the same way as the old one. Push the switch into the box and secure it with screws at the top and bottom. One black wire attached to top screw. Black means hot white signifies neutral and green indicates ground.