Installing an in-line switch to a lamp or light will add a measure of convenience to using the light. This holds especially true if the lamp itself is in a difficult or awkward place to reach. An in-line switch is a simple device that operates by interrupting the flow of current when it's in the "off" position, and allowing current to flow in the "on" position. Installation requires only basic tools and a few minutes of work.
Unplug your lamp from the wall socket. This will prevent electric shocks when you're working on the line.
Cut the power cord to the light with a pair of wire cutters at the place where you'd like to install the in-line light switch.
Strip the insulation from the wire on both sides of the cut, leaving about 1.2 to 1.8 cm (1/2 to 3/4 inch) of bare wire exposed on each lead.
Open your in-line switch. Most have one or two small screws, typically Phillips-head, holding the switch shut. Loosen the screws with a screwdriver and remove them. Then open the switch. Inside you'll find two screw terminals on either side of the switch proper. You'll attach the leads of the lamp cord to these.
Loosen the screw terminals on one side of the switch and slide one lead from one side of the lamp cord under each terminal. Then tighten the terminals to hold the wires in place. Repeat the process on the other side of the switch, with the other side of the lamp cord.
Replace the cover on the switch. Plug the cord in and test the switch. Be sure that the lamp's switch is in the "on" position, or your in-line switch won't work.
Don't forget to unplug your lamp cord. Never work on a live electrical circuit.