as previously stated, lots of reasons for things to catch on fire in autos and RVs.
now throw in the DIY van dweller and many of the "conversions" out there are veritable death traps
the vast majority of new DIY people are jumping on a project cabable of burning their rig to the ground with little or no knowledge/experience other than what they heard on youtube or around a campfire or on a forum.
one example i see/hear/read all the time is about charging from an alternator. 90+% of the time the question gets answered with "just use a constant duty solenoid" next thing you know you have someone hooking the house bank to the starter bank with undersized wire, bad connections, no chafe protection and no fuses.
yes i said fuses as in plural.
a reasonable installation of this kind would consist of reasonably heavy gauge cable rated for the current one expects to be charging. then there MUST be a minimum of 2 fuses sized to protect the weakest of 3 links. look at the max rating of the alternator, the max continuous load rating of the solenoid and the max current carrying capacity of the cable based on how long it is. chose the fuse size that is same size or smaller than the lowest rated of these three. then install one each as close as is feasible to EACH battery. you also need to be certain the wire that activate the solenoid when the engine is on is fused properly. if you tapped into a 20 amp circuit but used 14 or 16 awg wire, you are not protected. these size wires need smaller fuses or could cause a fire if they happen to get shorted.
all the connections need to have properly made crimps with appropriate insulation. this goes for every connection you ever make on your rig. bad crimps/connections can and do cause more over heat situations that can lead to fire than you can imagine. and a proper sized fuse will NOT save you. (SIDE STORY---- a few years ago at a well attended van dweller gathering i was asked if i could help as someones compressor fridge was not working as good as they thought it should. upon a cursory inspection i noticed a haphazard piece of electrical tape covering what looked to be a crimped terminal. when i asked they said they had done that because it got hot and had started to melt the insulation of the terminal/connector. under the tape i found a distorted insulator on a poorly sized and crimped terminal. i didnt have tools with me and was just there briefly so i instructed them to disconnect the unit till they could make repairs. they had food in the fridge and said that it had been like that for a while and left it running but promised to make repairs as soon as they could get the to the tools and parts. so far as i know, they did get that repaired. but if there was enough heat generated (with about 3.5 amps of current for the fridge) to melt the insulator in open air. imagine if inadvertently a dry towel had been set down on this and insulted it so the heat could not dissipate in the air. the temp of the bad connection could have easily risen to the ignition point of the dry towel. end result, rig goes up in flames, quite possibly when no one is there to do anything about it)
then we need to look at chafe protection, most of these charge off alternator installations will have cable routed through holes in body work and running through engine compartments and along frames or body sections. these wires need to be secured so they do not rub back and forth on something hard due to bounce or jiggle while rig is in motion. then anywhere that the wire makes hard contact or comes close to a sharp or thin edge like where it goes through a drilled hole in the frame or body some sort of physical barrier to wear needs to be used so the wires insulation does not become compromised leading to a short
look at all the places a diy project can easily miss something critical and it is no wonder with thousands of diy projects going on out there we have a few devastating disasters. and i just went over most of the basics. i didnt even get into making sure you used the right type of wire with insulation rated for the exposure it will have. wires in engine compartments need a higher heat rating. wires exposed to water, like under a rig need to be rated for such, old lamp cord from your house probably wont be rated for that. where does that wire/cable run? does it come close to anything that might impact it? i have seen power wires lying directly on top of catalytic converters. and the customer wondered why their aftermarket rear flood lights kept popping the fuse...
the same type of problems arise all the time, not just with electrical, but with propane lines, tapping into gas/diesel lines or modifying suspension systems
this is one reason folks like HDR, myself and others that have worked in these fields and seen the insanity and carnage first hand often sound like pricks when chastising or pointing out possible problems. it is not because we want to insult or chase off people from doing it. it is that we have done this enough to see the devastation when things go south and we care enough to try and prevent others from suffering the same fate.
