Wiring kill switch

[rainman]

I've searched on a number of message boards about this and there seems to be some confusion as to the proper way to wire a 4 post kill switch. Just wanting to get feedback from people on this board.

Thanks in advance.

[Director]

We interrupt the main positive cable to the starter and the main feed to the fuse box to kill the car completely in the event of an accident.
It works perfectly on the Sentra's & the Honda's we prep.

[rainman]

Perry,

Please excuse my electrical ignorance but are there any worries about the alternator feeding power to the system?

[Director]

Originally posted by rainman
Perry,

Please excuse my electrical ignorance but are there any worries about the alternator feeding power to the system?

I should have been more clear, that is what I meant. We kill the power to the starter, the alternator to the main electrical feed and everything goes dead when the kill switch is activated.

[apexhead]

An even simpler way is to run it to the ground of the battery.
Only if you are not using an electrical fire suppression system, of course.

[Director]

Originally posted by apexhead
An even simpler way is to run it to the ground of the battery.
Only if you are not using an electrical fire suppression system, of course.

We originally tried it that way, but because there are so many ground loops on the car, the engine kept running after we used the kill switch and took out the key. Go figure!

[Rich]

Originally posted by apexhead
An even simpler way is to run it to the ground of the battery.
Only if you are not using an electrical fire suppression system, of course.

If I read this correctly, then this is proposing interrupting the ground return to the battery.

Yes, this shoudl work in breakign the circuit, and stopping current flow, but it will leave all the electrical system connected to the battery on the positive side, and the danger of arcing to ground will still be there. Any crash damage could cause a short which then overheates and you have fire.....

(Yes, this does assume some kind of ground return still present to the battery..but as Perry posted, that still happens..)

I think interrupting the positive feed is better, then everything else is automatically grounded..

Rich.

[AndrewW]

The positive is the correct side to break, as recommended by OMP. When we tried to break the ground side, the car kept running as well.

[apexhead]

If you wire your car electrical to you on-dash "accessory" switch panel and every engine ground to your kill switch there is no reason to have a ground loop. It is also fairly dangerous to wire 12V current to a switch that is not grounded. In case your kill switch suffers damage in a crash or in lieu of excessive vibrations (which race car does not) I would rather have a ground problem than a positive current one. Your car will just stall. Just imagine your switch starts to spark while your sitting unconscious in a pool of gas. I've seen Sparco and Afco kill switches fail inspections on a few occasions and it wasn't a ground loop problem the switch had just given up. Some are just not made to be run road racing applications and are not water tight. Now I know that there are no rules regarding car wiring and that out of 20 cars on the grid probably none are wired the same but in most cases if there is no ground...there is no spark...I would just choose the safest alternative.
What ever works best for you.

Good luck!