Wire the dimmer for screw contacts
Use needle-nose pliers to smooth down the ends of the house wire. Now slacken a contact screw and gently wrap its exposed ends around the ends of a house wire, clock-wising around its shank. Fasten the screw’s head in order to secure the wire in place.
Wire the dimmer for pigtails
Flatten the ends of the house wires, using needle-nose pliers, and align one of the black house wires with the help of a pigtail wire. Now use pliers to twirl them clockwise, at least two times. Set a red wire nut over the connected wires and curl them clockwise until it is tight.
Install the switch’s cover
Use a flat-head screwdriver to set up the new cover plate. Flip the main electrical-panel switch back on its position, turn on the main switch and check your dimmer switch. Congrats, you have successfully installed dimmer switch.