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Thread: Master Switch Location

  1. #21
    Join Date
    Feb 2002
    Gainesville, GA


    This is a good discussion. It addresses several good issues. One of the small concerns I've had with the switch on the driver's side is that, on my car, the battery is on the PAX firewall. This means a 4-5 foot run of large wire that goes all the way across the car and is not isolated by the master switch. That is a potentially large area for a short in the event of an accident. I can convince myself it is the lesser of the available evils since I can have almost the entire length of the cable run under the dash, attached to the dash bar, and inside the confines of the cage and therefore, hopefully outside of the "crush zone".

    I had contemplated the idea of using a relay and switch or switches but wasn't sure if it would pass tech. As stated earlier, the switches would be low voltage/amperage and could be fused next to the battery although they would never technically be isolated.

    Ultimately, it's all a collection of compromises.

  2. #22
    Join Date
    Oct 2002
    newington, ct


    With the first car I built, I had the switch mounted on outside of the car with the thought process that the corner worker could easily reach it if need be.

    I got into an accident at Lime Rock, and found myself perpendicular to traffic a little ways after the crest of the downhill where cars couldn't see me until the last second. There was steam (hard to tell at the time and circumstances if it was smoke). The corner workers could not get near me for what felt like a long time do to where I was positioned. The whole time I kept thinking about how I couldn't reach the kill switch.

    For me, first priority is that I can get to the switch and turn it off. I've been in enough incidents to know (at least for me), this is the most likely situation. If I were only to do one switch, it would be on the drivers side roll bar where I could reach it as well as a corner worker.

    For the kill switch itself, if you don't use Stephen's method, get the heavy duty metal kill switch instead of the crappy plastic one. I've had those fail too often.
    Dave Gran
    Real Roads, Real Car Guys Real World Road Tests
    Go Ahead - Take the Wheel's Free Guide to Racing

  3. #23


    I agree with Greg that it is important that the driver be able to kill all power. I had this discussion with the tech guy that issued my log book. I mentioned that the GCR does not state that the driver needs to be able to reach the kill switch. He agreed that this should be in the GCR but for some reason is not. It is far more likely that the driver will be in a more favorable position to kill the power than a corner worker.
    Mike Taylor
    1995 MX-3 LeChump/ITX

  4. #24


    For folks doing a new install and not wanting to run welding wire into the cockpit, take a look at

    I helped a friend put it into his Miata. The device sits between the battery ground and frame, and has a 2nd circuit to kill the fuel pump or ECU.

    The trigger wires are small and you can run multiple. We put one near the driver and one outside for cornerworkers.
    #08 ITA/STL Miata



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