[TR] electrical outlet on a TR3A

Randall tr3driver at ca.rr.com
Thu Feb 11 12:35:58 MST 2010


> If your car is + ground you'll have to reverse the wiring, 
> chassis ground to the central tip and powered wire to the 
> plug's side. 

That is exactly correct, but it leaves a danger lurking.  Some plug-in
devices have the negative side (the shell of the socket) connected to
exposed metal.  If that exposed metal touches pretty much any metal part of
the car, you now have a short !

This was brought home to me many years ago, when a friend temporarily
installed a CB radio in his positive ground MGA.  He clamped the antenna to
the rear bumper and wired the radio in being careful to observe polarity
(but not so careful to chose a fused wire).  It worked, at first, so we set
out on our road trip.  Couple hundred miles later, the rusty bumper mounts
vibrated enough to finally make good electrical contact with the rest of the
car, and all the smoke leaked out of his wiring harness !

-- Randall  


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