Master Cutoff Switch

Travis Miller · 03-22-2019, 09:57 AM

After returning from a month "down South" working Div 2 races including both the Baby Gators and the Gatornationals I must comment on an important issue I found missing on a lot of racecars.

As stated in the 2019 NHRA rulebook, master cutoff switches MUST be clearly marked for the OFF position. That means both the left-right lever style and the push-pull type.

It would seem simple to turn the switch off if an incident happens on the track. But let's look at it a different way. After an incident on track the first person to arrive at the scene will turn the master cutoff switch to the off position. The second person arriving may not know that the switch has been turned off and turn it the other way which would turn the system back on. This can happen when the switch is NOT clearly marked.

The other one is the push-pull type. Everyone knows that push OFF is the way these switches work....or do they. Marking with a PUSH OFF label will assure that in an incident the power gets turned OFF. All it takes is for one person to pull the switch and the system is reactivated.

Marking your master cutoff switch is a simple yet very important way to let everyone know which way is OFF.

MR DERBY CITY · 03-22-2019, 12:31 PM

Thanks for the heads up Travis....that’s some valuable info right there....

cmracing · 03-22-2019, 08:27 PM

It would only make sense for a push-pull type of lever to turn the power off when pushed, as in backing the car into a wall. But, common sense has not been too common for many, many years........

Any car I work on has that switch properly marked, I never want anything to happen to one of my friends or customers, as well as myself and family members driving one of our cars!

CMcAllister · 03-22-2019, 10:09 PM

Rulebook states "push" must be the off action on a push-pull type mechanism. And most of the levers on switches I'm aware of go CCW to turn off if it's mounted that way. Also states it must be marked.

I'm a fan of having some type of secondary cable or other way of operating the master from the driver's seat, for both safety and convenience.

Larry Hill · 03-23-2019, 06:47 AM

I have one in the car next to me that kills everything, just in case!

FireSale · 03-23-2019, 02:18 PM

Quote:

Originally Posted by Larry Hill

I have one in the car next to me that kills everything, just in case!

Ditto.

Keith 944 · 03-23-2019, 04:09 PM

Quote:

Originally Posted by FireSale

Ditto.

This Might be part of the problem, you get in an accident, shut your power off, first guy there thinks he’s turning it off and has turned it back on...
It should also be mandatory if you have one inside the car it moves the lever outside the car also, which I’m sure most people already do

Larry Hill · 03-23-2019, 09:19 PM

The disconnect inside the car will not be affected by the outside disconnect being in the on position. The outside disconnect feeds the inside disconnect.

w

FireSale · 03-23-2019, 10:24 PM

Quote:

Originally Posted by Keith 944

This Might be part of the problem, you get in an accident, shut your power off, first guy there thinks he’s turning it off and has turned it back on...
It should also be mandatory if you have one inside the car it moves the lever outside the car also, which I’m sure most people already do

When I had a push-pull system, I had a cable running from the trunk switch to a lever in the cockpit, Pushing the lever physically moved the rod on the back bumper. Since emergency persons are trained to move that switch, they could possibly turn the car back on. My current setup is a rotary switch on the back deck that cuts all power between the battery and the car. The power feed into the cabin is through a continuous duty Cole Hearse solenoid connected to an aircraft switch on the console to energize it. If something goes haywire I can slap that switch and kill all the accessories and ignition power. There is still one hot wire in the cabin (the battery cable) but the juice isn't going anywhere. It's a quick way of shutting off the ignition and fuel pump without flipping multiple switches.

Jeff Stout · 03-24-2019, 11:27 AM

If I have battery in stock location and add a second battery in back do I need a master cut off switch?
I think I don't but asking as I need to add a battery.

03-22-2019, 09:57 AM	#1
Travis Miller Member Join Date: Jun 2007 Posts: 478 Likes: 1 Liked 276 Times in 27 Posts	Master Cutoff Switch After returning from a month "down South" working Div 2 races including both the Baby Gators and the Gatornationals I must comment on an important issue I found missing on a lot of racecars. As stated in the 2019 NHRA rulebook, master cutoff switches MUST be clearly marked for the OFF position. That means both the left-right lever style and the push-pull type. It would seem simple to turn the switch off if an incident happens on the track. But let's look at it a different way. After an incident on track the first person to arrive at the scene will turn the master cutoff switch to the off position. The second person arriving may not know that the switch has been turned off and turn it the other way which would turn the system back on. This can happen when the switch is NOT clearly marked. The other one is the push-pull type. Everyone knows that push OFF is the way these switches work....or do they. Marking with a PUSH OFF label will assure that in an incident the power gets turned OFF. All it takes is for one person to pull the switch and the system is reactivated. Marking your master cutoff switch is a simple yet very important way to let everyone know which way is OFF.

03-22-2019, 12:31 PM	#2
MR DERBY CITY VIP Member Join Date: Feb 2014 Location: Derby City, USA Posts: 3,636 Likes: 1,083 Liked 7,928 Times in 1,517 Posts	Re: Master Cutoff Switch Thanks for the heads up Travis....that’s some valuable info right there....

03-22-2019, 08:27 PM	#3
cmracing Member Join Date: Aug 2016 Posts: 173 Likes: 113 Liked 62 Times in 29 Posts	Re: Master Cutoff Switch It would only make sense for a push-pull type of lever to turn the power off when pushed, as in backing the car into a wall. But, common sense has not been too common for many, many years........ Any car I work on has that switch properly marked, I never want anything to happen to one of my friends or customers, as well as myself and family members driving one of our cars!

03-22-2019, 10:09 PM	#4
CMcAllister Senior Member Join Date: Sep 2006 Location: Fulton County, PA Posts: 614 Likes: 16 Liked 920 Times in 259 Posts	Re: Master Cutoff Switch Rulebook states "push" must be the off action on a push-pull type mechanism. And most of the levers on switches I'm aware of go CCW to turn off if it's mounted that way. Also states it must be marked. I'm a fan of having some type of secondary cable or other way of operating the master from the driver's seat, for both safety and convenience.

03-23-2019, 06:47 AM	#5
Larry Hill Live Reporter Join Date: Oct 2004 Location: Hickory, Ky Posts: 10,633 Likes: 1,928 Liked 10,687 Times in 2,225 Posts	Re: Master Cutoff Switch I have one in the car next to me that kills everything, just in case! __________________ IHM Used Parts https://ihmusedparts.com 888-821-1817

03-23-2019, 09:19 PM	#8
Larry Hill Live Reporter Join Date: Oct 2004 Location: Hickory, Ky Posts: 10,633 Likes: 1,928 Liked 10,687 Times in 2,225 Posts	Re: Master Cutoff Switch The disconnect inside the car will not be affected by the outside disconnect being in the on position. The outside disconnect feeds the inside disconnect. w __________________ IHM Used Parts https://ihmusedparts.com 888-821-1817

03-24-2019, 11:27 AM	#10
Jeff Stout VIP Member Join Date: Dec 2001 Location: phoenix Posts: 1,486 Likes: 66 Liked 704 Times in 281 Posts	Re: Master Cutoff Switch If I have battery in stock location and add a second battery in back do I need a master cut off switch? I think I don't but asking as I need to add a battery.