How to Wire into an Existing Light Switch

How Can I Wire into an Existing Switch that Controls an Outlet? The Most Common Problems when Wiring Light Switches and How to Fix Them, Wiring Switches with White Wires. © By: Dave Rongey

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Wiring a Switch
Electrical Question: How Can I Wire into an Existing Switch that Controls an Outlet?

• I am installing a ceiling fan with a new ceiling box and new Romex wiring.
• I want to tie into an existing switch that controls an outlet.
• The switch has black and white wires.
• I combined the blue and black wires for the light and fan, then pig tailed to the black wire at the switch and did similar with white and ground at switch.
• This does not work. Any help would be appreciated.

This electrical question came from: Rick in Santa Clara, California.

Dave’s Reply:
Thanks for your electrical wiring question Rick.

How to Wire to a Switch that has White Wires

Application: Ceiling Fan Circuit Wiring.
Skill Level: Intermediate to Advanced – Best performed by a Licensed Electrical Contractor.
Tools Required: Basic Electricians Pouch Hand Tools, a non-aluminum ladder and Voltage Tester.
Estimated Time: Depends on personal level experience, ability to work with tools and access to the switched outlet wiring and the proposed location for the ceiling fan.
Precaution: Identify the switch power circuit, turn it OFF and Tag it with a Note before working with the wiring.
Notice: Installing additional electrical wiring for a ceiling fan should be done according to local and national electrical codes with a permit and be inspected.

The Most Common Problems when Wiring  Light Switches and How to Fix Them

• The biggest misunderstanding when it comes to light switch wiring is that when a white wire is seen it will be assumed that it is a neutral wire.
• Realistically this is not always the case, especially if the white wire is connected to the light switch, which is a clear indication that the white wire is being used for switching power, and not for a neutral at that specific location.
• When wiring for lights or outlets a neutral wire is required, and one way to identify a neutral wire is buy using a voltage tester and understanding the circuit wiring.
• Most experienced electricians can open up  a few junction boxes and understand exactly the circuit wiring, but this is not the case if you are inexperienced.
• If you are in doubt then please give your local electrician a call, they will be happy to give you a hand.

More about Wiring Switches and Ceiling Fans

Wiring Ceiling Fans

How to Install Ceiling Fans

• Take the mystery out of ceiling fan wiring.
• Ceiling Fans are a great way to lower your energy bill and brighten up one of your favorite rooms.
• Step-by-step pictures – Easy wiring diagrams and installation guide – Light and fan switch variations.

Ceiling Fan Wiring
Ceiling Fan Wiring diagrams
Electrical Outlet Wiring

• Wiring Electrical Outlets for the Home

• Home electrical wiring includes 110 volt outlets and 220 volt outlets and receptacles which are common place in every home. See how wiring electrical outlets for the home are done.

How to Wire a Switch

Wiring a Light Switch – Diagram 1

Wiring Diagrams

Fully Explained Light Switch Wiring Diagrams. Detailed Electrical Wiring Diagrams and Pictures assist your Home Electrical Projects.

Guide to Electrical Wire

• Electrical Wire for the Home

• Complete listing of electrical wire types and parts used for home projects with electrical code information serves as selection guidelines.