Date:         Thu, 30 Apr 2020 11:59:15 -0700
Reply-To:     Steve Williams <sbw@SBW.ORG>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Steve Williams <sbw@SBW.ORG>
Subject:      Re: Horn installation
In-Reply-To:  <CAFdLW6n4N1-Z+L2uBT=EHGy2WR1M5b77bj5pcxdjANG2KKQGGw@mail.gmail.com>
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> ... a wire running from pos (+) of battery to the horn ...

Not that, in any case!  A short, heavy wire to a fuse, and from there a
wire sized appropriately to the horn's current requirements.

In my Westy, a wire burned up about two years ago while the van was
parked in a busy area of downtown Santa Cruz.  My five-year-old nephew
was strapped in the rear seat when a lot of smoke billowed from the
right front wheel well.  Yes, right next to the fuel filler.  It was
VERY upsetting.  I thought the whole van was about to go up.  I yelled
at a passerby to call the fire department and grabbed my terrified
nephew and took him to a bench down the street with another random
stranger who offered to comfort him.  I ran back and saw flames inside
the wheel well.  By the time I retrieved the fire extinguisher and
prepared to use it, the fire and smoke were gone.  I got a flashlight
and crawled under the van to carefully look at everything.  I saw it was
a burned wire, so I disconnected the batteries and tried not to pass out.

It was an ordinary wire, maybe 16 awg, running UNFUSED from the positive
terminal of the starter battery, out the bottom of the battery
compartment, forward, draped over the suspension, then to port, draped
over the spare tire, and into an bundle of wires that ran from under the
left side of the dash, aft under the car and up into the closet.
Evidently, somewhere the burned wire had chafed against the frame and
shorted out.

I'm embarrassed to admit that in almost ten years of ownership, I had
never investigated that wire.  I had replaced the battery a couple of
times, always just reconnecting the three wires attached to the positive
terminal.  I just assumed all were appropriately sized and/or fused.

After that wire burned up and I followed it as far as I could to remove
its charred remains, I assumed it was something installed by an idiot
previous owner for no purpose I could see.  (Nothing stopped working
after it burned or after I removed it.)

I asked a few shops what that wire might have been.  Eventually, Marco
at Buslab told me it might be the power wire for the air conditioning,
installed by the dealer after the van was imported from Germany.  (I
long ago took the belt off my compressor.  I keep meaning to remove all
the components and get some storage space back.)

I'm a fully-qualified avionics technician.  I've added lots of aviation
grade wiring to the house conveniences.  There's no excuse for never
having investigated such an obvious hazard.

Don't be like me.  Check that all the wires attached to the positive
battery terminal are sized and/or fused appropriately.