Master Kill Electrical Switch (Page 1 of 2)

AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAHHHHHHHHHHHHHHHHHHHHHHHHHHH NNNNNNNNNNNNNNNNNNNNNNNNNOOOOOOOOOOOOOOOOOOOO!!!!!!!!!!!!!!!!!!!

Hey, we shouldn't jump on newcomers just because a subject has been discussed so much (on the old Lemons Yahoo group, not so much here) and/or has caused everyone so much tech-inspection pain. Better to have endless discussion here than get more racers screaming at the tech inspectors at the race. The BS Inspection is right next to the tech inspection area, and the judges get headaches from excessive screaming over there.

Yes, Fogbert, most Lemons racers use a double-pole/single-throw kill switch, which interrupts battery power on one pole and ignition coil power on the other. Some racers also interrupt the field wire on the alternator, so as to prevent the (endlessly debated) potential badness of alternator diode burnout.

This has been discussed a lot and I think it's here as well as the Yahoo Board. 

There is a diagram on the Yahoo Board.

http://f1.grp.yahoofs.com/v1/QBd8SukyVa … ctions.pdf

Here is a simple way to do it.

Using a double pole kill switch.  Run your battery and alternator charge wire to one side.  Run the wire or wires that power the car to the other side.

On a lot of cars, you can run the alternator straight to the battery and run a typical battery wire to the starter as well.  Then you will really only need to run is a heavy gauge wire, lets say, 10 gauge to the switch since it only carries the power for the accessories in the car.

We have huge wiring run to and from our switch because no one had that revelation until after we wired 2 cars.

Hey Troy, the link you posted is dead.  Is it gone, or did the link just not work?

Why do you need a 4P switch? If you wire the Alt feed  to the battery side of a single pole switch, won't that kill everything?

We didn't use the Longacre one, but we do have a 4-pole switch.  From what we have been told by some NASA racers, the problem with these switches is they aren't designed to be turned on/off like a light switch.  IOW, they are to be used in an emergency and not for many, many on/off cycles.

If you kill the batt and the alternator, the engine has to stop....with the heavy alt power wire connected to the batt side of a 2P switch, what's left to run the coil?

Thanks for the help, and the generally gentle responses. I DID try to find this subject on an existing post but was unsuccessful (my surf & search skills are even less than my electrical skills). It looks like Mulry's explanation and a $30 switch should get me through tech.  If any of you are at CMP next month, and #92 is reduced to a smoldering pile of steel, you can at least say you tried to tell me...

Our SHO and the other 2 SHO teams use the cheap ass Harbor Freight switch. So far so good.

That's right. The main fuse box wires run right by on that side.

Can it be located on the passenger side on the hood right next to the windshield?

Please tell me I don't need to relocate it. This switch has taken way too may hours away from our build already.

Just as a heads-up... If you're planning to run in ChumpCar, too, then you'll need to move it. Their rules are pretty explicit on the placement.