Battery Cut Off Switch

[Kurt B.]

This may be a dumb question, but I have never used one of these so here goes.
I purchased one of those switches with the knob and you make or break the connection at the battery by turning or removing the knob.
I thought it was supposed to go on the positive terminal but it seems to be a very tight fit.I may have to spread it apart to make it fit.
Is it supposed to go on the negative terminal?
Does it make a difference which terminal I mount it on since it breaks the connection either way.
Thank you in advance,
Kurt

[Jack H.]

Re: Battery Cut Off Switch

It doesn't make a difference where you open circuit the battery...open circuit is open circuit (battery disconnected and can't supply current unless the loop is completed). Batteries have two different sized terminal posts (one slightly larger around) to help prevent connecting the battery to the car in reverse polarity. That's why you were 'fighting' to cram the disconnect switch on the positive vs. negative post....

[Kurt B.]

Thank you Jack *NM*

[Stephen L.]

Re: Battery Cut Off Switch

As Jack said it doesn't electrically make any difference which pole you open. However, by opening the negative terminal you eliminate the possibility of shorting the positive pole or wiring to ground when working on a circuit, as ground was "removed" by the switch. This is also true when replacing a battery; remove the negative cable first. You don't care if you touch a grounded point with a wrench when removing that cable. This eliminates the possibilty of touching a grounded point when removing the positive cable as the "grounded" point will no longer be connected to the battery.

[John H.]

Re: Battery Cut Off Switch

The switch is designed to be installed on the negative battery terminal - the hole in the switch is sized only for that terminal.

[Roger S.]

Re: Battery Cut Off Switch

See my side terminal battery hook-up

Roger

[Roger S.]

Re: Battery Cut Off Switch

Here is the bigger picture.

Roger

[Kurt B.]

Re: Battery Cut Off Switch

Thanks to all for the input.
After all these years I learned today the reason for cutting off the negative connection vs. the positive.
Thank you gentlemen,
Kurt

[Gerard Q.]

Pic of my neg battery cutoff install *NM*

[Dave R.]

Re: Battery Cut Off Switch

Roger that set up you have is beautiful; did you make that or is it something that can be purchased? I want to get a disconnect for my '69 but, always wondered how it would fit in such a tight space.

[Paul L.]

Blade Switch

Here is another option for C3 owners: a Wirth blade switch.

[Garry Barnes]

Re: Blade Switch

Paul, I have seen blade switches advertised in the Driveline and around. Is there a difference in the one that you have? Wirth? Where did you find it? Thanks.
Garry

[Dick G.]

Re: Blade Switch

I had one of these knob switches on my old 57. Now, I have a Savety switch. Working in the electrical field all these years has made me a believer in "A Visible Disconnect". When you turn that knob to open the circuit, you can't see "a visible disconnect". Is the circuit definately open? Can you see an air gap in the circuit? NO. It's cute and compact, and IMHO, should not belong on our prized possesions. Some of these cars are worth more than what some folks pay for their homes. That being said, even the knob switch is better than nothing at all. Just my opinion. DG

[Paul L.]

Re: Blade Switch

Garry,
The blade disconnect came from JC Whitney. I do not know how it differs from those in the Driveline but it is very sturdy.

http://www.jcwhitney.com/autoparts/Product/tf-Browse/s-10101/Pr-p_Product.CATENTRY_ID:2006121/p-2006121/N-111+10214+600010591/c-10114

[Paul L.]

Blade Switch on My 1967

A bit off topic I suppose but here is the setup on my 1967.