Battery cutoff switch location

[nick7405]

with my past experience I have always positioned the cutoff switch on the negative terminal of the battery however everybody's build thread has them in them on the positive. Is there a right and wrong?

[BEAR-AvHistory]

I think the hot side (red) is better. Cars now have more than one path to ground so killing the battery ground strap does not always kill all the possible paths to ground for individual components.

Personally I have directly grounded a number of individual units.

FWIW my cutoff is here:

https://thefactoryfiveforum.com/attachment.php?attachmentid=105224&d=1554745065

Easy for me to reach with the 5 point belts on.

[AC Bill]

There are pro's and cons. Sanctioned race organizations have varying rules, on which way to wire them, if you plan on racing it.

Personal choice, so I went with the negative side cut-off.
Every automotive service manual always mentions removing the negative battery terminal, before beginning repairs. Once that ground is cut off, there is no way a circuit can be completed. I suppose if you ran other grounds, such as for accessories, to the battery post itself, there is a possibility of still completing a circuit, as they would not be controlled by the cut off switch. Otherwise, I don't know how else there could be any ground, once the switch is turned off?

In the worst case scenario, a crash could cause the battery's positive post, to contact the frame, or aluminum panels, which could be dangerous. Likewise with the exposed switch cable terminals. Even the positive cable that runs to the cut-off switch, if it were cut, or crushed could cause arcing. A positive wired cut off switch wouldn't prevent that, as a negative wired switch would. Plus a broken switch, or cut/crushed, negative wire, won't cause any shorting.

Years ago, I read on the other forum, of a fellow who had his cut off switch crack, and break off, as he was driving. He had the switch mounted in the rear bulkhead,as Kevin's is shown. Apparently the half of the broken switch with the positive cable still attached, was swinging around below the car, bouncing off the frame, and suspension, with sparks flying everywhere. It scared the heck out of the owner.
Unless wired correctly, a cut off switch won't always kill the engine immediately. It's more of a security feature for me, or if I'm working on the car.

[RoadRacer]

I did positive cutoff, between the seats. If I was doing sprints again I'd put one on outside of car..