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How To Install an In-Line Switch on a Lamp Cord

Learn how to install an in-line switch on a lamp cord.  This will allow a lamp to be controlled without having to plug or unplug the device.  This article gives step-by-step instructions on the simplest method of wiring an in-line switch on a lamp cord.

In some situations, it is desirable to install an in-line switch to control a device (such as a desk lamp, or an under-counter light, allowing the device to be turned on and off without having to pull the plug in and out of the outlet. I recently had a question from a website client asking me to show how these are to be installed and connected.

Some things to consider are:

1. Is this the most convenient way to control the device?
2. Is the in-line switch rated for the proper voltage and current of the device being controlled? In this example, the switch is rated at 6A at 125V (a 75W bulb will draw less than 1 amp on 125V).
3. Is the in-line switch physically the correct size for the lamp cord that I want to install it on?

The in-line switch is a very simple device that interrupts the current flow to the lamp by connecting or disconnecting the hot wire. Most lamp cords are one color (white, black, silver, and in this case, gold) so how do we determine which wire is the hot one?

The hot wire is the conductor that is connected to the narrow blade of the male plug, and it can be difficult to trace exactly which one it is, but on all approved lamp cords, the neutral is the ‘identified’ conductor, and they identify it by putting a ridge on the side of the neutral, or by making it rough to the touch in comparison with the hot wire.

Once you have identified the smooth or the hot conductor, then we can proceed to install the switch.

1. UNPLUG THE DEVICE (obvious, but crucial step!
2. Open up the switch by removing the small machine screw in the center of the switch. (Be careful not to lose the tiny nut on the back side of the switch!)

3. Carefully split the 2 conductors of the lamp cord apart about 1”(depending on the size of your switch) at the location that you want the switch located on the cord, using a sharp knife such as a utility blade knife.

4. Leave the neutral, or identified conductor intact as it has a channel to feed through the switch uninterrupted.
5. Cut about about a ¼” out of the hot conductor (smooth) using a diagonal plier (side-cutter).

6. Lay the cord in place on the bottom half of the switch. (Note how one conductor feeds through, and the hot wire will be penetrated by the small brass spikes to make the connections to each side of the switch).

7. Put the top half of the switch on to the base and squeeze together using your fingers until the brass spikes have penetrated the insulation and are touching the stranded copper inside.

8. Put the nut back in to its recessed holder, and tighten down the machine screw firmly, but not so tight that you break the switch, or strip the screw.

9. Plug in the cord and test your work!

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  • Hello, this is unquestionably a seriouslyoutstanding submit. In concept I’d wish to generate like this as well – taking time and genuine effort to create a brilliant post.!!!. but what can I say… I procrastinate alot and never seem to acquire anything done. Thank You


    Thank you! That was really helpful 🙂

  • flowers

    Very helpful! The kit I have was very confusing.

  • Melanie

    Thank you!

  • Thumbs-up on this one….. Thanks to your step-by-step instructions I was able to connect on the first attempt….. I’m a “ten thumbs” kind of handyman so you
    receive a “thumbs up” from all ten!!!

  • Pat Magroin

    Thanks – My lamp was shorting out and an internet search brought me here. Worked the first time!

  • Rahul Daya

    Thanks sooooooooo much for your help!!

    It really does work it was up and going in 5min!
    Thanks Mr..

  • Fcherrmann

    Thanks – been wondering about hot & neutral in a cord – glad to know narrow blade is HOT and hot is the SMOOTH wire.

  • AJ

    Nice tutorial! Thanks for posting this.

  • MrsDover1

    I purchased the exact same switch you have illustrated.  My holiday light uses a 7 watt bulb and the electrical cord supplied with it does not show a distinction between the insulated cord wires other than there is small print on one side.  The wide side of the plug is on the printed side.  I assume this is the neutral side as you have discribed.  Put everything back to gether after following your instructions and it does not work.  Help!

    • Irene

      Very clear and exact instructions and diagrams which made my first attempt work, thank you so much.

  • Tshapiro

    This article describes exactly what needs to be done to wire an in line switch on a corded plug. It clearly communicates the way to identify the hot and neutral wires while laying out easy to follow steps to complete the job. The fixture manufacturer and switch maker both had no wiring diagram to help me assemble this switch, lucky for all of us this website will teach you how to do it in just a few minutes.

  • Jan

    thank you so so much! How stupid are the instructions that come with these things!?! Took 5 mins after reading your post to get it working…after spending about an hour trying to figure out the instructions in the box!!

  • Troyce

    Thanks for the easy step by step instructions! Worked perfectly for my project and was very simple to install with your help! Thank you 🙂

  • Chris

    awesome instructions. I did not have to buy a new cord. Thought I made a mistake trying to install it the first time but after reading your instructions realized that I had placed the wire in backwards.

  • Jose

    excellent. thank you, found these instructions on the first search I made “how to install a lamp “thumb” switch”.

  • Mary

    Thank you! The best I’ve ever seen. I just installed my first inline switch and lived to tell, thanks to your video. Even with polarized plugs it is important to identify the neutral wire and I couldn’t find an ‘explanation for dummies’, (me) before. Now I’m going to rewire my 220V dryer (just kidding). Thanks again.

  • Joe

    Thanks these instructions helped a lot

  • Colby Gauge Knox

    How can you wire 110v lights to a 220v breaker..?


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