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Kill Switch (also known as an Electrical Master Switch)

Installing a kill switch is not as complicated as one may think. Avoid the temptation to over-think this process and make it harder than it really needs to be. The hardest part in completing the installation is determining how to properly wire the unit so it properly “kills” all power to the car. The before-and-after illustrations take care of this step for you.

Kill Switch Before

Kill Switch After

Kill switch installation illustration notes:

  • For safety reasons, remove the battery connectors when completing the necessary wiring.
  • When splicing the ignition wire, use 14 gauge wires.
  • New cable connector – crimp ring connectors on the ends of the starter cable, main power circuit cable, and the new cable (heavy gauge wire) that you are utilizing. Then use a bolt and washer to connect the three cables together.

Kill Switch PictureWhen shopping for a kill switch, purchase a unit that is built to cut-off the vehicle’s alternator. The reason for this is that with many cars, even though the battery may no longer be providing power, the alternator still provides enough power to keep the car running.

Once the kill switch wiring has been completed, it’s time to ensure that it works properly. Start the car then turn the kill switch off. The next simple test is to turn the headlights on, then again turn the kill switch off. If wired properly, the headlights will turn off. (You may also use a voltmeter to ensure that no current is flowing to the engine.) After verifying that the kill switch operates properly, use electrical tape or shrink wrap on all exposed connections, including on the kill switch, battery, and new cable connector.

Where to mount the kill switch?

On Hood  On Cage  

You will see people mount the kill switch in various locations. Two factors in making this decision is keeping the switch accessible for a corner worker to turn off, as well as yourself when belted in the car if need be. Because of this, my recommendation is to put it inside of the cockpit near the drivers side window.

When I first mounted a kill switch, I thought it would be a good idea to put it on the hood of the car. At the time that made sense to me as it was easily accessible to corner workers. Unfortunately while out on track one day, I was put into a situation where it would have been beneficial to turn the kill switch off. Since I was still on the race track surface, workers could not safely reach the kill switch. I was totally fine and could have turn the kill switch off, that is if I could reach it. From this experience I learned that there is quite a bit of value in me having access to the kill switch while belted into the car.

Assuming that you do mount the kill switch inside the cockpit, again, make sure that you keep it easily accessible to someone outside of the car. While having it located near the center of the dash might be easily accessible for the driver inside the car to turn off, it makes it very difficult for someone outside to access.

Summary of Primary Costs:

  • Kill switch: $35
  • Heavy gauge wire. One option is to purchase an inexpensive set of jumper cables and cut the clamps off the end. $15
  • 14 gauge wire: $6
  • Ring terminals (6): $4
  • Male and female wire connectors: $4
  • Electrical tape (one roll): $2