been have troubles with my light switch over heating for yonks till today i realized it was a faulty join further up the wire creating the hot spot which then inturn heated the switch so i rejoined all these connections and what do ya know light work fine, then travelling home from work a flame shoots out form under the dash. Instantly i need a new pair of pants as i swerved to the side of the road and switched off the car jumped out to grab water from the boot and cut off the battery by the time i got back in the car the fire was out and my interior speedo light didnt work the new wire lit on fire now i gotta figure out what the heck went wrong :S hope someone can learn a lesson or get some humor from this near miss

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Enjoy Chris

sounds like you had abit to much power running through those wires, wires have a grade of power they can handle to much will cause a melt down i.e fire or melting casing, thin wires which are normal for lights and interior electronics are thin and handle low voltage, thick wires like ur battery and starter motor cable are think cause they use higher voltage like i said u have to much voltage running through those wires, i would check ur alternator out since that generates the power while the motor is on and see how much volts it puts out to the car to much can sometimes cause this if there are not fuses connected or fuses are of a higher rating then the actual wires and electricals itself. normal alternator will generate about 13.5 to 14.2 volts with lights and stuff on ( e.g lights and wipers on) id check that first then go along the wires to find faults or cracks then check ur fuses are the right grade and are all working

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oil leak?..what oil leak..that puddle under the car is just sweat from all that horsepower

yeah it was 10amp wire which is what was on it before the repair except buy fixing the hot spot i seemed to have turned the entire wire into a hot spot and melted the casing off the entire thing then the entire wires casing caught on fire i learnt my lesson

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Enjoy Chris

awesome

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Howard: "You don't need a pen to be a writer Vince"
Vince: "I think you do"

Once you cause a "hot spot" you have turned the wire from being a fairly efficient conductor into a fairly crappy jug heating element.

Once the wires have been damaged, they now have some resistance in them and will turn 12volt DC into bulk heat. Cut your loom back as far as the damaged wire(s) goes, and replace as necessary. Twisting wires and electrical tape won't cut it with these repairs, best use solder and use a little heat shrink.

If the melted wires disapear into the loom, best try and dig them out, as they tend to melt into other wires, no matter what they are. Ground wires are the dangerous ones to melt into here.

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

I'm sorry but this whole answer is utter bulshit. It might sound mean but why do the people insist on answering when they obviously dont know what the hell they are talking about?
It reminds me of how Borat describes the weather report on Kazakh television "rain maybe come, maybe not come, maybe come. anything can happen, only god knows".

Anyway a "faulty join" probably wont cause your light switch to heat up. It'll heat up if there's a short in the circuit or if one of the lights connected to the circuit draws a very high current (essentialy the same thing). It sounds like there's a short somewhere in the vicinity of your speedo light (probably a stripped wire rubbing on a grounded panel) - the speedo lighting is activated together with the side lights from a terminal on your light switch (note this is a different terminal to the headlights terminal).

The whole "shooting flame" situation seems pretty extreme as the auxilary lighting wire is thin gauge and drws fairly little current and if it was shorted the usual would be a meltdown with a bit of smoke (on clubbies its fused anyway). A flame would suggest a thicker wire being shorted (there are only 4 of them in that area: +12v to the headlight switch, +12v to the ign switch, +12v from the ign switch, and +12v to the headlights) or maybe a spark caused the petrol fumes behind the speedo to ignite. But in any case you must hunt the problem down and fix it before you drive the car again or you'll end up with a proper fire.

Poor contacts within light switches can start to generate heat, and cause it to carbon up, this in turn self feeds the cycle and the switch gets worse. The heat conducts up the wires to melt the insulation. This will continue until something gives.

I'll guess if the switch was involved, the issue here started with a bad spade connector or switch contact, and then after the repair something came away and the wire shorted against the frame.

That's my guess.

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

I think the biggest thing people have overlooked in this thread is the fact that you were going to throw water on what sounds like and electrical fire. Im not a Firefighter but my job involves dealing with fires in cars. For god sakes use a chemical extinguisher, throwing water on electrics will get you killed.

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With great power comes great responsibility. It also comes with one kick ass ride.

Water isn't a bad thing on 12 volts dc. Water is a bad thing on anything above a couple of hundred unless you're only concerned about corrosion. It's actually a very efficient insulator.

If it came to allowing the mini to burn to the ground or a wet carpet, I know I would be getting the hose and wetting mini electrics down with gay abandon.

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

wow didnt realise this would genarate such strong response. i cut of the battery with a cut off switch first to minismise the possiblilty of a bad zap if i used water i have a small chemical extinguisher in the car now and im not using the lights till i fix them. it was a fairly thick gauge wire and it didnt melt on a single hot spot but the entire wire melted then burnt right back into the loom also i have a bit of oil leak from my pressure gauge and a occasional petrol fume smell which may have helped. funny u mention only 4 wires going into the head light swith i have 2 tabs on the switch which have 2 wires going onto the one tab(dad did the electricals) im beginning to question this as the wire that burnt and melted was only for the speedo lights etc even tho they worked previously

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Enjoy Chris

I would definately look at the switch as part of the fix....what has been said above is right...once contacts have arced over a few times they tend to start tracking through the plakky/bakelite body of the switch.

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"Show me the Mini!"

If you haven't done it already, I strongly suggest adding a fused headlamp relay (New Era or similar).
This reduces the ~12A headlamp load through both the headlamp and dipper switches to milliamps.
They are real easy to install, schematic is on box.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

So 12 volts is going to kill you? Makes you wonder why the yanks take so much effort in making the electric chair. By the sounds of things all they need is a bucket of water and a car battery.

A chemical extingusher is more likely to cause you harm than a bucket of water on a car fire.

LOL found the problem F#@KING CHEAP WIRE caught on a piece of metal rubbed through and shorted on the body ZAP thank go it was cheap cost about 20cents solder and some decent wire to fix took 10 minutes now im happy although im keeping the fire extinguisher in case :S thanks for your comments

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Enjoy Chris

by the way anyone else had any close call fire situations in there minis or other cars???? can be funny to look back on and can be a valuble lesson for us younger blokes to learn about wiring and mechanical safty i learnt the hard way that u shouldnt weld next to a petrol soaked rag (i was 15 and stupid, now 18 and in denial of stupidity) :D:D

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Enjoy Chris