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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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