How to Change a Double Electrical Switch in an Older Home

Turn the breaker off that supplies electrical power to the double electrical switch. Remove the screws holding the duplex cover to the original double electrical switch. Pull the duplex cover from the double switch to expose the electrical wiring.

Test the circuit with a two-wire tester to make sure the electricity is correctly disconnected. Touch one of the wires from the two-wire electrical tester to one black wire on the double switch; touch the other wire from the tester to any bare metal on the switch. If the tester fails to light, the circuit is disconnected correctly from the switch. Repeat for all black wires connected to the original double switch.

Wrap masking tape around each black aluminum wire connected to the original double switch. Mark on the masking tape the location where the black wires connect to the double switch terminal screws. For example, TL for top left, TR for top right and BL for bottom left.

Remove the original double switch from the electrical box by removing the screws from the bottom and top. Pull the switch out from the electrical box and loosen the terminal screws that hold the black aluminum wires to the switch. Pull the aluminum wires from beneath the terminal screws.

Orient the new CO/ALR-rated double switch to match the orientation of the original switch in the electrical box. Wrap the black aluminum wires around the terminal screws on the switch that correspond with the marks you made on the tape-wrapped wires before you removed the original switch.

Tighten each terminal screw on the new double switch to hold the aluminum wires to the aluminum terminals. Carefully push the new switch into the switch box and connect it with the included screws.

Install the original duplex cover over the new double switch. Turn on the breaker that supplies electrical power to the double electrical switch.