[AT] Discharge Chains

Steve W. swilliams268 at frontier.com
Fri Apr 1 18:33:33 PDT 2016


Indiana Robinson wrote:
> Check the grounds.
> Check the grounds.
> Check the grounds.
> :-)
> Those were ground straps made of conductive rubber, some had fine wire in
> them and I think some just had a lot of conductive carbon in the rubber.
> Many that you bought at a parts store or the old J. C. Whitney catalog had
> a lightning bolt painted on one face of them. They started putting them on
> cars around 1950 or as little ealier when they were switching from cloth
> seats to plastic seat covers. Those dang things could really nail you when
> your feet touched the ground or you reached over and touched another person
> who had just slid into the car.
> I don't really recall the trucks here ever dragging chains or a strap... I
> do recall always grounding a tractor when doing flat belt work usually with
> a steel bar or sometimes a chain. I did normally drag a chain from the rear
> axle of my SP combines for two reasons. One was for a ground to keep the
> windshield cleaner and the other was when dragging about a 6' piece of well
> secured fairly heavy chain when running corn in wet weather it saved
> crawling under a combine in the freshly churned mud to hook a chain or tow
> strap to the axle to tow it out backward if you get stuck.
> As far as lightning goes the best explanation I ever read was by a weather
> scientist (I can't spell meterihffjikist right now) who said that a bolt of
> lightning may well have traveled over 20 miles across the sky... It is
> silly to think it is now going to stop for 4 inches of rubber.  :-)
> As to metal skins or wire cages you can Google Faraday Cage Effect.
> In wood working we often use plastic pipe on dust collectors and it is bad
> about building static. You can ground it either by running a bare wire
> inside or outside and to a ground. You don't need a wire for metal pipe as
> long as a ground connection is maintained at one end or the other. That
> mostly applies to commercial woodshops and sawmills etc. In a home shop you
> just don't want the plastic to be zapping you all of the time.
> In commercial shops there can be risk of fire or dust explosion from static
> sparks. In spite of a lot of wild stories floating around on the web I have
> read that there is no statistical record of a home shop explosion or fire
> in a dust collection system unless there were flammable solvents being
> used. Still better safe than sorry I guess. As they say "It couldn't hurt
> anything".  :-)
> 
> 

There is a wood fabrication shop near me that so far has had at least 10 
fires in the dust collection system. I had a minor pop in my extractor a 
  while back. No solvents (just really DUSTY barn wood). The biggest 
worry in this immediate area is a grain/feed mill that has dust built up 
from the early 1800's... Used to be water powered but switched to electric.


-- 
Steve W.



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