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1966 Ford Mustang
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Discussion Starter #1
i installed fog lights and For the last two months they have been working great until today when I noticed smoke coming out from under the dash and a big spark. The blue with black stripe wire that I connected the fog fuse to for power has melted away. It was very Scary and I quickly unplugged the battery to prevent fire and damage. I looked under the hood and I noticed that the wires coming from the two fog lights and that is feeding in the firewall have had some contact with the engine bay and some of it is stripped out. Could that be what triggered the fire under the dark ? On the other hand, the inlet fuse that has the two studs that came with the fog light had also been touching the dash metal. I have not had the chance to screw it into the wiper motor bracket. I am just so scared that it doesn’t happen again and I would like your input as to what you think may have caused the fire. I bought myself a fire extinguisher just in the event it happen again. I have spent over 15K worth of upgrade and rebuild on this car and I want to make sure it does go into ash :(
 

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That "fuse with two studs" is a circuit breaker for the fog lights and one side of it is always "hot". There is no fuse between the CB and the battery stud on the starter solenoid where it receives it's power. If that stud touches any metal you have a direct short and since there's no fuse wires will start melting.
 

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1966 Ford Mustang
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102 Posts
Discussion Starter #3
That "fuse with two studs" is a circuit breaker for the fog lights and one side of it is always "hot". There is no fuse between the CB and the battery stud on the starter solenoid where it receives it's power. If that stud touches any metal you have a direct short and since there's no fuse wires will start melting.
So you are saying that the circuit breaker must have touched the metal on the dash since it was laying on it but not the melted wire that is coming from the fog light into the fire wall that was stripped out due to the heat from the engine bay. I had suspected the circuit breaker therefore I had tape it all around for now until I have the time to secure it on the wiper motor bracket. Thank you for the explanation. And just for my understanding would this have caused more fire or it would just melt away and stop ? I was afraid that the spark would be strong enough to ignite the entire car. Next time if this happens do you have a recommendation other than disconnecting the battery
 

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1966 mustang coupe
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47 Posts
The amount of fire would be determined by the materials touching the hot wire, fabric will smolder and catch fire, plastic will melt and can eventually burn.
 

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Disconnecting the battery is the quickest, easiest and safest way. Without power going to ground through a wire, there will be no heat in that wire.
 

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1967 Mustang GT fastback
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I suppose if you're worried about the always hot side of the circuit breaker, bolt it down to the wiper support and you'll be good. If there are loose wires or other things hanging nearby (?) then cover the rest of the hot terminal with electrical tape or cover it with an appropriate diameter rubber vacuum cap.
 

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And always make sure that any wire that gets power (key off or key on) are properly insulated (heat shrink, tape, etc.). I NEVER leave power wires exposed because you never know when a pothole/curb will shake it loose.
 
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