How to Make Your Own Kill Switch
- 1). Select a durable toggle switch and matching wire. Your local electronics store will have a wide variety of toggle switches available, and their suitability for your application will depend largely on the type of device you will be controlling with the switch. For automotive applications, select a very heavy grade switch (as well as a length of heavy gauge wire) to handle the large amount of amperage generated by the vehicle. For lighter applications, like hobby equipment, select a toggle switch and wire with an amperage rating sufficient for your needs.
- 2). Locate the wire that powers the device you wish to protect. Most direct current (DC) devices use two wires, one positive (usually red) and one negative or ground (usually black). You may install the kill switch on either of these two wires, though interrupting the positive wire may provide slightly more reliable security. Although the power wires for your particular installation may vary, the most direct access to power wiring can generally be found at or near the battery terminals. Be sure to disconnect the wires from the power source before beginning any sort of electrical work.
- 3). Cut the power wire. After you have identified the wires that provide power to the device you wish to protect with the kill switch, use wire cutters to cut the positive (red) wire near where it connects to the battery. Strip away a small (about one half inch) amount of insulation from each end of the newly cut wire to reveal bare wire.
- 4). Splice in a length of wire. In order to mount your kill switch in a convenient location, you will need to splice two lengths of wire onto the wire you cut in Step 3 above. Use your wire cutter to strip away about one half inch of insulation from one length of wire you purchased in Step 1 above. Align the newly exposed wire with the exposed end of the power wire you cut it Step 3 above, use your fingers or pliers to twist the two exposed wires together, then wrap the splice with electrical tape. As an alternative to electrical tape, you may also use plastic electrical caps specifically designed to hold spliced wires together.
- 5). Mount the kill switch. Identify a location for your kill switch that is convenient for you to reach during normal operation of your device. Mount the switch in a hidden, but easily accessible location using screws, double-sided tape, a mounting bracket or any other method appropriate for your installation. Run the lengths of wire spliced into the power wire in Step 4 above to your newly mounted kill switch.
- 6). Attach the wires to the kill switch. With the kill switch mounted and the wire ends loose near the switch, attach one end of the wire to one terminal on the switch. Since the switch physically interrupts continuity of the electrical circuit, it does not matter to which end of the switch you connect which wire. Connect one wire to one terminal on the switch, and secure it in place using either electrical tape or by soldering it. Repeat this process for the other wire and switch terminal. With the wires attached to the switch and all connections secure, your kill switch is successfully installed.
- 7). Test your kill switch. Move the newly installed toggle switch to the "Off" position, then attempt to power on your protected device; the device should not start (if it does, you have spliced into the wrong wire and you will need to repeat Steps 2 through 6 on the appropriate wires). Next, flip the toggle switch into the "On" position and attempt to power on your protected device; it should power on normally. If the device fails to power on, or if it does not appear to operate normally, verify that all spliced connections are securely attached.
