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Replacing a Light Switch and Changing the Wiring

Dina in Maryland asks; How do I connect the wires when replacing my light switches? How to Replace a Light Switch and Make the Wiring Connections, Identifying the Wiring, Connecting the Wiring for Your New Switch.

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Wiring Light Switches
[ad#block]Electrical Question: How do I connect the wires when replacing my light switches?

I need to replace a single light switch, but when I pulled the old switch out of the wall here is what I discovered:

The switch has three wires attached to it, in addition to the grounding wire. Two of these wires are pushed into the back of the switch, the 3rd one is around one of the screws on the side. The new switch that I bought only has two screws, not counting the grounding screw. How do I connect this? I’m not sure if all three of the wires going into the old switch are “hot” or if only two are hot, which ones they are. What would that third wire be from? I also noticed on the old switch that it says “CU and CU Clad Wire only.” This means that I have copper wires, not aluminum, correct?

Thanks in advance for any help you can provide.
This home electrical wiring question came from: Dina, a Homeowner from Baltimore, Maryland.

Dave’s Reply:
Thanks for your electric wiring question Dina.

How to Replace a Light Switch and Make the Wiring Connections

Application: Wiring for a Light Switch.
Skill Level: Beginner to Intermediate – Best performed by a Licensed Electrical Contractor.
Tools Required: Basic Electricians Pouch Hand Tools and Voltage Tester.
Estimated Time: Depends on personal level experience and ability to work with tools.
Precaution: Identify the light circuit, turn it OFF and  Tag it with a Note before working with the wiring.
Notice: Installing additional electrical wiring should be done according to local and national electrical codes with a permit and be inspected.

Electrical Wiring for Light Switches

Identifying the Electrical Wires When Replacing a Light Switch

When Connecting the Wiring for Your New Switch, this is what I Recommend:

Electrical Wiring Abbreviations and Terms about Light Switch Wiring

More about Wiring Light Switches

Light Switch Wiring
Light Switch Wiring

Electrical wire

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Complete Guide to Home Electrical Wiring

Perfect for Homeowners, Students,
Handyman, Handy Women, and Electricians
Wiring GFCI Outlets
Wiring Home Electric Circuits
120 Volt and 240 Volt Outlet Circuits
Wiring Light Switches
Wiring 3-Wire and 4-Wire Electric Range
Wiring 3-Wire and 4-Wire Dryer Cord and Dryer Outlet
How to Troubleshoot and Repair Electrical Wiring
Wiring Methods for Upgrading Electrical Wiring
NEC Codes for Home Electrical Wiring
....and much more.

Be Careful and Be Safe - Never Work on Energized Circuits!
Consult your Local Building Department about Permits and Inspections for all Electric Wiring Projects.

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