I understand that's a possibility, and common in European cars, but I didn't take from Jason's post that he is running the ground circuit through the master, just that he is bypassing the master on his starter wiring.Originally Posted by DanW
I could be wrong.
-Mark
Mark Uhlmann
Vancouver, Canada
'12 Stohr WF1
IMO, it's easier to have just a single wire to disconnect using the ground side. On my car there are several things directly connected to the positive battery terminal, so I'd have to make sure they were ALL disconnected when turning off the master switch. See my typical wiring diagram in post 39 ( https://www.apexspeed.com/forums/sho...l=1#post633404 ). It's different on my Zetec but still switched on the negative side.
Dave Weitzenhof
Another advantage of having the disconnect on the ground side is that if you use a jump battery for starting you can start and run the car on the jump battery and not draw any current from your car battery for starting, there by saving all car battery capacity for the track.
john f
Your reply is appreciated but that can also be accomplished by connecting the jump battery positive to the switched side of the disconnect (with the disconnect in the on-board positive lead from the battery). I'm curious as to if there is a technical or safety reason for putting the disconnect on the ground/negative. I like to run a single wire to a terminal strip at the dash board and distribute the positive from there. Makes diagnosis and isolation or changes easier.P1000422.JPG
There is a glitch in the continuum...
IMO, as long as the switch disconnects everything that could conduct current in an emergency situation, there is no safety related difference between + and - location of the switch. Either side has potential current flow when connected. As long as it disconnects all possible current paths, that's what it needs to do.
Last edited by DaveW; 12.05.21 at 11:54 AM. Reason: eliminated redundancy
Dave Weitzenhof
Now THAT's an extremely neat wiring setup! It makes my wiring look ratty in comparison.
Dave Weitzenhof
The Hella switches usually have copper terminals and a bar (to connect them) but the marine ones are all stainless. This means when you look at the back of them, the 'bolts that you attach wires too" (=terminals) are also silver (vs copper). An easy check.
Aside from the bouncing from vibration causing pitting, the copper ones do not handle water well and can start to corrode (as well as pit). Implication is if you race a lot in the rain, change them more often. I suspect the pitting (and hence poor conduction) is much worse when the force on the bar is less (due to bounce). The bodies wear in the cam mechanism. Implication is this part has a number of cycles til it need to be thrown out (or at least compared to the new unit in your spares box).
You may want to read what the switch is supposed to do. I'm pretty sure the switch is just required to shut down the car in an emergency. Nowhere does it say the starter needs to be electrically disabled, or all electrical systems isolated from voltage. In an emergency, do you really care that the starter is disconnected? All I know is that for 20+ years tech hasn't questioned it, and a hella master switch has never caused me a DNF. I have personally seen it happen many times. The fact that this is even a discussion/concern says these types of master switches should be eliminated if at all possible.
Kill/Master Switch - GCR
9.3.34. MASTER SWITCH
All cars, except Touring, and B-Spec shall be equipped with a master switch easily accessible from outside
the car. Spec Racer Fords (SRF/SRF3) shall be wired per RFSRII. The master switch shall be installed directly
in either battery cable and shall cut all electrical circuits but not an on-board fire system. All terminals of the
master switch shall be insulated to prevent shorting out...
The bold font is the critical sentence, IMO.
Last edited by DaveW; 12.05.21 at 8:59 PM.
Dave Weitzenhof
When it's off you want everything OFF (single exception for electrical fire actuator).
Caldwell D9B - Sold
Crossle' 30/32/45 Mongrel - Sold
RF94 Monoshock - here goes nothin'
Cuts all electrical circuits. If the ignition switch controls power to all circuits (fuel pump, rain/brake lights, push button for starter, etc.) then cutting power to that ignition switch does cut power to all circuits. It gives no clear definition of what a "battery cable" is. Is the battery cable the wire that feeds power to the rest of the car? If it is, and if that wire connects the roll bar switch, and the following ignition switch which controls all other circuits of the car, then it is legal. So a plain old toggle switch located at the roll bar satisfies the requirement.
Last edited by 10rmotor; 12.05.21 at 11:53 PM.
So long as that toggle switch can carry enough amps to spin the starter motor....
There is a glitch in the continuum...
No it doesn't say that. There is no mention of starter current. If you shut off power to the ignition switch which controls power to the starter button that satisfies the requirement of cutting power to all circuits. Typically its tested by starting the car and shutting off the roll bar switch. If the car dies it passes. In an emergency, that starter current isn't flowing anyway and doesn't need to be shutoff, so why bother with it?
From a safety standpoint, you wouldn't want a large cable mounted up high where its vulnerable, and you'd want it as short as possible as this limits the exposure of a high amperage capable conductor directly connected to the battery. As I said, in a bike motor the solenoid can be mounted right next to the battery so that larger cable can be very short, and the remaining starter cable is only energized at startup. The way I wire the master, I only use a #12 wire to a 20 amp breaker switch. The ignition switch is also 20 amp.
A circuit is a path for current to flow. Therefore, a direct battery wire from your battery's 12V to your starter's high current terminal is a circuit.
I appreciate completely your logic that the starter solenoid cannot be triggered if your "master toggle switch" is off. However, that is not the letter of the rule which is clear that ALL circuits must be interrupted by the master switch.
The fact that no tech inspector has had an issue with it is also not the same as it being compliant. I'm not trying to split hairs here for fun nor do I have any products to sell or any other axe to grind. I just want to make sure that no fellow formula/sports racer enthusiast takes an approach and then ends up in a jam when they get to an event IF my understanding of the rule is correct.
-Mark
Mark Uhlmann
Vancouver, Canada
'12 Stohr WF1
There is no definition of circuit in the GCR, as I've already said. Your interpretation of circuit is just that. IMO, my method has less potential exposure by keeping the high capacity cables to a minimum, and their location least vulnerable, in addition to not requiring a crappy hella master switch to be used. If you want to continue to use garbage components that are major failure points by all means continue to do so, its your car.
It's not a circuit if it can't carry current.
If the solenoid can't be triggered, then the starter "circuit" is NOT a circuit.
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