On topic: Serious static problem

From: Christian Fandt <cfandt_at_netsync.net>
Date: Fri Dec 4 15:19:19 1998

At 11:12 12/04/98 -0800, Aaron C. Finney wrote:
>This is giving me fits. There's something strange with my minivan, that it
>generates a *ton* of static electricity whenever I drive even a few
               -- snip --
>box of Bounce dryer sheets (don't laugh) in my jockey box. Does anyone
>know what could be causing this?

Yes. It's not the car but it's the tires. I've had the same problems with a
couple of Toyota Camrys I've leased over the past years. Extreme and rather
painful shocks are generated especially in this part of the country when it
is very cold and low humidity.

Finally getting tired of the fireworks, I asked a few tire dealers and auto
dealers about this and they told me that modern tires nowadays have
somewhat less carbon black, which is conductive, in their rubber compounds.
Something about reduced wear, etc. Static charges built up from the motion
of the tires over the road don't drain off as fast. Hence, when you step
out of the car you get nailed. This is because the resistivity of the tire
rubber is higher because of less carbon black content. Carbon black,
incidentally started to be put into tire rubber back around 1910-1912,
IIRC, when it was found that it drastically reduced the damage to the
natural rubber caused by the sun's UV rays. Tires up until then were as
white as the original rubber tree sap was when harvested and did not last
very long. You can see examples of reproduction white tires on
correctly-restored antique cars from around the early teens and earlier at
an antique car show or auto museum.

I found a solution by holding my fingers on the unpainted door jamb
hardware as I turn and step out of the car (if I'm wearing normal
rubber-soled shoes). This keeps my body and the car at equal potentials as
the static continues to drain off through the less resistive tires. Minimal
or no zaps anymore.

I worry a bit about those shocks at the gasoline station if somebody is
fueling their car and there is a significant concentration of fuel vapors
and no wind about. It takes at least a 14:1 air to vapor ratio for ignition
to occur which is not too likely at the gas bar.

I have a pair of ESD-type work shoes which I wore at work and still wear
around the house. There is a high amount of carbon in the heels and soles
which allows them to be used as an anti-static device for electronics
workers. I never get nailed in the house on a carpet nor from my car
whenever I wear them. They're great! Made by Titan Safety Shoe Company.
Needed them in the cleanroom at work and when repairing electronic controls
around the plant or working up in the R&D lab. Additionally, I recall that
I had very little problem when I wore leather-soled shoes back in the days
when I had them. Seems the leather was a bit conductive especially when damp.

Incidentally, do some of you remember the automobile accessory fad from
back in the 70's which was an anti-static strap that hung from the bottom
of the car? If it was conductive it would serve a good purpose for you
today Aaron. You've probably seen fuel tanker trucks with a metal chain
dragging. It too was used as a static drain for obvious reasons ;)

Happy zapping! --Chris
-- --
Christian Fandt, Electronic/Electrical Historian
Jamestown, NY USA cfandt_at_netsync.net
Member of Antique Wireless Association
        URL: http://www.ggw.org/freenet/a/awa/
Received on Fri Dec 04 1998 - 15:19:19 GMT

This archive was generated by hypermail 2.3.0 : Fri Oct 10 2014 - 23:30:47 BST