• Forum membership has its advantages....

Switches and Circuit Breakers

johndjmix

Well-Known Member
#1
When it comes to switches and circuit breakers, I notice most trucks using simple (proboly mil-spc) metal toggle switches with breakers below them. Im getting ready to do a new dash and have a few questions...

1. Why does everyone use the plain jane metal rockers. Durability? Space usage? I would like to use mil-spec contura switches, any notes about that?

2. On the circuit Breakers. So lets say we have 5 circuits coming to a panel in the truck, lets say all the circuits are clicking over relays. So your putting the circuit breaker on the high-current side of the of the relay...but what about the hot that energizes the relay? Is everyone just feeding that from the circuit breaker right below it, so its a short wire run = very little chance of a short? Or are you feeding the switch area with one protected circuit, say 5A, and using that to all the switches? It would seem that method 2 has a common point of failure and should be avoided.

Im very very experianced in wiring and electrics, but, being new to the truck world here (coming from ATV's) im curious how its done by most of you.

--John
 

07FJRog

Well-Known Member
#2
Eliminating as many relays as possible the better.
I use a common fuse/ breaker for my low current side for no more than a group of 3 relays. Just my choice.
The milspec sealed switches are very durable, so that is why most of that style are used.
I used almost all carling in my truggy build though, and no issues in two years, but i would not hose them on purpose.
 

_

Well-Known Member
#3
RE: Mil-Toggle vs. Contura (Mil-Spec toggles as typically used by professional motorports wire service providers.)
1) There is no such article as a Mil-Spec Contura switch (Mil-Spec means there is a proper Military Specification on record along with an assigned Military Spec "MS" number)
2) Mil-Spec Toggles are more readily available and in a significant greater number of actuation configurations and pole numbers (over Contura Switches.)
3) Mil-Spec Toggles have far greater reliability in harsh environments over Contura switches.
4) Mil-Spec Toggles have a higher operating temperature over Contura switches.
5) Mil-Spec Toggles are far more easily mounted than a Contura switch.
6) Mil-Spec Toggles are available with screw terminals, a far more reliable termination over the typical Fast-On terminal of the Contura switches

RE: Circuit Breakers and Relays (not sure you understand the proper application and proper wiring of relays.)
1) Relays are less reliable than a quality Mil-Spec Toggle Switch
2) Relays are typically used when the current capacity of the switch is not capable of reliably handling the current load through the switch. (Note: A four pole Mil-Spec toggle is capable of handling up to 60 amps (total of 4-poles) when properly wired.)
3) When using a switch to activate a relay, the switch is used to activate the Relay Coil.
4) The switch can supply the high side or low side of the relay coil (your option when wiring)
5) Circuit Breakers should always be installed between the +12V Source and the Line Side of the Switch and/or Relay. (IE: 12V source to the Line-Side of the Circuit Breaker, Load-Side of the Circuit Breaker to the Line-Side of the Relay.) (This provides the greatest amount of protection to the greatest amount of the wiring.)
6) The Load-Side of the Circuit Breaker can also be wired to the High-Side of the Relay Coil with the Switch supplying the Low-Side of the Relay Coil.
7) Using switches with a greater number of poles will provide opportunity for greater current capacity for a single switch, greater number of independent circuits through a single switch, greater opportunity to reduce the number of switches required for a single vehicle, greater opportunity for more creative functionality for a single switch.
8) Using a switch to provide the High-Side of the Relay Coil, the 12V source for the switch can come from the same Circuit breaker as used for the Line-Side of the Relay, or from a Circuit Breaker of a far lesser trip value specifically intended to supply power exclusively to Relay Coils.
 
Last edited:

Mark Newhan

Well-Known Member
#4
Look into PDU's. Life racing and Motec have some great ones. They are pricy. Now days keypads are becoming the norm.

There are a couple of alternatives. Motobrain and Switch Pros are worth a look at. I haven't used them yet, but would love to try them on a prerunner.

This is the new command center I did in the 27.
 

Attachments

johndjmix

Well-Known Member
#5
ProFORMANCE, I have a very good understanding of the proper use of relays and breakers. Im just wanting to know "the way its done" in a race vehicle normally....no reason to do things a different way then after spending a whole lot of time on it finding there is a reason its being done "this way". I.E. no reason to reinvent the wheel.

Thank you for all of the information though!

Although I will probably go with standard toggles, but I do disagree on the "There is no mil-spec contra". If you look up the info on carlings web site you will see tons of specs "...Per Mil-Std 202F" and others. Im no expert with military specifications but to me I would think this means they have a mil spec switch.

--John
 

_

Well-Known Member
#7
John,

Just because a manufacture manufactures a component which in-part conforms to a particular military specification, does not qualify the component as a Mil-Specified component, and does not automatically assign a MS number to that component. Only the Military has the authorization to write a full and complete call-out of a Military Specification and these specifications will identify every aspect of the part in its entirety, not just a limited number of parameters regarding the component. Example: If you build an item which conform to IP67 or IP68, this does not mean the item you built has is a Mil-Spec item, it only means the ingress of water and dirt meats IP67 or IP68 specification.

This is a common mis-understanding by many in this industry. I see persons regularly mis-represent components and/or workmanship as Mil-Spec (which in fact are not Mil-Spec) either out of lack of respect for, -and/or- ignorance of, what Mil-Spec truly means. You came on this forum to obtain a better understanding of the wiring practices by professional wiring service providers in this industry and to obtain greater details on the why-for's and what-not's as to these practices and the materials used, yet you take the information you receive and Poo-Poo it. Why waste peoples time if you are Quote: " very very experianced in wiring and electrics. "

Side Note: The Mil-Std 202F (which you are using to support your argument the Contura Switch is a Mil-Spec switch) is no longer a recognized Military qualification. Mil-STD 202F was done away with in 1998 and replaced with the more stringent 202G. Any company who represents a component as qualifying to Mil-STD 202F is basically saying the component qualifies to an outdated and un-recognized, non-existent qualification, which in turn nullifies any recognition/argument of conforming to "Mil-Spec." in any nature.
 
Last edited:

green787

Well-Known Member
#8
The thing about an old style chrome toggle switch is that you can spray WD-40 in there and toggle it a few times and make it work one last time before replacing them... And they are available almost anywhere.....
 

johndjmix

Well-Known Member
#9
I get what your saying proformance, I agree saying you comply with a standard vs having an actual proven compliance and a number assigned by the mil / compliance authority. Good info here.

--John


Dunarri LLC
wildscooterparts.com
coolermods.com
 
Likes: _

07FJRog

Well-Known Member
#10
To say that 202f is unrecognized and non existent is incorrect, the fact that it has a superseding 202g does not make it not recognized any longer. But parts that relate to the 202f will now need to be 202g in a military apllication, where specifide by the appropriate manuals that list that part.
Some 202f parts may not have to be upgraded to the new 202g, it can and does vary sometimes.
21 years of Navy service here in Electronics
 

Co-Dog

Well-Known Member
#11
You just got an education from one of the best in the industry and immediately disrespected him for his trouble. Shame on you. Maybe he will accept your apology.

I don't participate much anymore, but after reading this post, I had to have a look at the "Contura" line of switches. LMAO! There isn't anything about those switches that even comes close to a real Mil Spec. switch. They may meet a Mil Std. but that don't make em Mil Spec. I could go on and on, but I'll just state the obvious, if it's got quick connector tabs on it, it doesn't belong in a race car. . . period.

Yes, the Conturas are pretty and would probably be fine for a pre-runner if you stay out of the silt, but as my Dad used say, "Chrome won't get ya home." It took me a long time, a lot of money and plenty of misery before I understood what he meant.

Damn, I'm cranky. Enough said . . . . .OUT.
 

Slippery P

Well-Known Member
#12
PDU!
Eliminate a majority of wiring, all relays, and breakers.
The key pads are c.a.n. Networked to the PDU this is they way it's being done now days.
 

johndjmix

Well-Known Member
#13
I defiantly appreciate the info from PROformance.....so,

I guess we will find out, well.....I did panels with both types of switches. Made 2 panels on the CNC, can swap them in under 3 minutes, will carry the "real mil spec" one in the truck just in case.

Since we sell Contura Switches here, im curious how they will last. BWDC then baja on the next race list so we will find out there. Ill probably go to a motec system in the near future anyways.

--John
 

desertspeed

Well-Known Member
#14
7) Using switches with a greater number of poles will provide opportunity for greater current capacity for a single switch, greater number of independent circuits through a single switch, greater opportunity to reduce the number of switches required for a single vehicle, greater opportunity for more creative functionality for a single switch.
Gary, thanks for your willingness to share your wiring knowledge, I have learned a lot from you over the years.

Can you expand on #7 though, with maybe an example of what you mean? I have always used mainly single pole switches for single purposes and am having a hard timing imagining how to use a single switch for multiple purposes. I guess in a race car there are a few switched components that you would always want on together, but I can't think of many other applications where that would work.

Thanks!
 

green787

Well-Known Member
#15
I believe he is saying that where you might use a single pole switch to turn on a helmet blower for instance.... Use a double pole switch with the poles jumpered together, so that you have twice the contacts working for the same device... therefore Half the risk of it going bad.... seems reasonable to me....
 

retroblazer

Well-Known Member
#17
People need to chill. There is very helpful info in this thread. How about some specific examples of switch choices like a helmet blower. I use what I believe is a peak of 9 amps for my Jabsco, 150cfm rated, marine bilge blower. Another switch need is for auxiliary cooling fans for engine and trans. And what is the range that good switches cost? I assume there are hobby parts, and primo exotica parts.
 

johndjmix

Well-Known Member
#19
FYI, so far so good with the contura's. only one race on them so we will see.

I'll keep everyone posted.

--John


Trophylite #6013
Dunarri LLC
wildscooterparts.com
coolermods.com
 

johndjmix

Well-Known Member
#20
Figured I would update. 2 years now running Our own brand of “contura” style rocker switches. Been through several BITD races in the race truck and Zero issues. Got to run what we sell to test!

—John


Sent from my iPhone using race-deZert
 
Top