Simple Wiring question

[Scott e]

Hey guys.

I bought a disconnect switch to shut down all electric from the battery.
The directions with this thing specify to install from the negative side of the battery.
Doesn't make sense to me. Why would you not install from the positive side of the battery to switch?

Thanks in advance.

scott e

[narly1]

I vote for negative.

https://www.motortrend.com/how-to/kill-switch-positive-or-negative/

Earl

[ggunter]

Actually, you can install it from either side, and it will work. All you are doing is breaking the connection from the battery. How ever, if you have a length of positive battery cable from the battery to where ever you install your switch. That length is subject to shorting if rubbed or pinched anywhere along the way to the disconnect switch. The ground side will disconnect the battery and if that side of the cable gets rubbed or pinched it won't make any difference because its already grounded. I think that is their reasoning behind putting it on the negative side.

[Mastertech5]

If you are using a computer for your engine most need constant power on one circuit for memory. You need to not disrupt that circuit with the cutoff switch. Run a wire around the switch for that circuit.

[narly1]

If you are using a computer for your engine most need constant power on one circuit for memory. You need to not disrupt that circuit with the cutoff switch. Run a wire around the switch for that circuit.

Hmm, given this and the fact that many automotive circuits use the frame as a ground return perhaps there is merit in locating the switch on the positive side.

One could always fit the +ve run with a mega-fuse right at the +ve post if there is concern about a short occurring somewhere between the battery and the cut-off switch.

Earl

[Mastertech5]

From reading many build threads, mega fuses, as you mention, are commonly added.