wire loads

[Superfab]

When I wire race cars I use Klixon circuit breaker switches on everything. They give excellent circuit protection and let you know if you have a short. They operate like a regular toggle switch. They are not cheap..about 80.00 ea but neither is the cost of a race. As for figuring wire load ranges Ace hardware sells a book "Pocket Ref by Thomas J. Glover "that has a chart of maxumum wire length (Feet) for car wiring. It tells you all you need to know.

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[Jack]

The wire and switch should be able to handle it depending on the fan. Just go 25% over the max draw. The wire size is fine. What the problem most likely is, is the conection at the switch. Is it just a crimp on then slide on to spade? These are notoriuos for melting. You must solder the wre drirectly to the switch termanal if you want it to last in the dust.

[Dezertpilot]

The new switch I am using (50 amp) has the connections as a screw on type. The wire gets crimped on to the round eye and that gets screwed on to the switch. How will this work?

[OldStroppeTeam]

The new switch I am using (50 amp) has the connections as a screw on type. The wire gets crimped on to the round eye and that gets screwed on to the switch. How will this work?

I prefer to solder the ends on the wire, crimps don't always stay crimped....

[DJDIRTWORKS]

30amps.... but if you have a direct short to ground yer screeewed.
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A direct short should not be a problem-you should just blow a fuse or trip a circuit breaker. If you havent protected your wiring with fuses or breakers, your are asking for big trouble. Electrical fires caused by shorts(rubbing, chafing, vibration all make this a very possible occurance)can quickly turn into whole vehicle fires. An unprotected wire shorted out will flow a huge amount of current until it melts in half. I don't remember the exact temp. , but copper melts at something like 1100 deg. F. I seen too many vehicle fires due to this problem. One other thing, where you place your overcurrent protection in the circuit is critical as well- put it in the wrong place and and it's the same as not having one.
As far as what caused your problem, like some one else said, a loose connection will cause that. Also, a cheaper or under-rated switch will also melt. The switch or loose connection can not handle the heat caused by the current flowing through it( current flow, as well as resistance, induces heat) and as a result begins to distort. When this distortion becomes severe enough, an arc will occur, an arc is hot enough to melt metal, and now the distortion becomes worse, causing a bigger gap for the arc to jump, causing more resistance, causing more heat... it just turns into a runaway reaction until either the components melt "open", breaking the circuit, or until everything burns up...
Superfab is right , use breakers- they protect your gear and usually give you a visual indication of what circuit has failed. If you cant afford breakers, use fuses. They are now making fuses with blown-fuse indicator lights built right into them that are pretty handy. AutoZone I know carries them.

[Dezertpilot]

So what about an inline fuse holder with a 30 amp fuse? I think Ill run that this weekend when I get some time. I am planning on doing some rewiring this weekend and I will take your guys comments into consideration. So where could I purchase one of these circuit breaker systems at? What are the specs on these? Do they handle multiple accessories? Any one have any links? Id like to check these out....thanx.

[Dezertpilot]

Oh and where can I get these Klixon circuit breaker at? Any piks? Oh and I like the blown fuse light idea seems pretty handy.

[frankh]

Never understood why people think a relay fixes a currant problem. You need to switch a circuit that has a 20 amp draw. You can either use a manual switch or a relay. No matter what you have a set of contacts that need to handle 20 amps. It does not matter where the contact are at. The relay is made mainly for two reasons are. 1- To remote the contact- this is so you can limit the run of large wire. Not a problem on a race car. 2 - To isolate a person from a high voltage. Again not a problem for a race car. The big thing to remember is a fuse or circuit breaker as close to the battery as possible.

[Superfab]

You can get Klixon breakers at http://www.aircraftspruce.com/cathome.php . They are series 7270-1. They come in 3,5,10,15,20,30,35 amp ratings. Check the amperage rating of your fans. If they are 22 amp run a 30 amp breaker on each. This way if one fan burns up it doesn't take out the other. A 10 ga wire is good for about15 feet @30 amps. Run at least an 8 ga wire to feed the breakers (You can jumper them together with a 10 ga wire). Nice part is if the breaker pops the switch goes to the off pos which is easy to see. No guessing and if the fan smokes it wint kill the wires. Most fuse holders don't like the surge of the fan turning on and they can smoke the fuse contacts. I don't know what brand or model fans you have but the most common mistake is running too much stuff off one circuit and overloading it. Most good fans take at least 15 amps on up to run each! Most switches you buy will burn up over time due to arcing of the contacts especially with near capacity loads. If you look at most top class one or tt they use breaker switches cause they don't fail. I hate being parked with electrical problems so i get a little anal about using good stuff. Besides, we never geet enough seat time for $ spent anyways.

[Kbach66]

I prefer to solder the ends on the wire, crimps don't always stay crimped....

I've never been a fan of soldering wires....too much vibration equals a broken wire. I've never wired any offroad vehicles, only on-road race cars and motorcycles, so I'm sure the vibration amounts/frequency is pretty different.

I guess if you're gonna solder it, make sure it's secured well to the chassis as close to the solder/connector joint as possible.