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A Lucky Discovery

jw0752

     No matter how many years I have been involved with electronics I still make decisions that have unfortunate consequences. Several weeks ago I noticed that the shop chair was chewing up the floor in the shop where I spend most of my time. My solution for this problem was to patch the nicks in the concrete and to purchase one of the large flat plastic sheets that are used in offices. The floor was now protected and the chair seemed to glide from position to position with more ease than before. I was happy with my supposed improvement to the shop.

 

     Tonight as I reached for a screw driver in my tool cabinet I noticed that my Fluke Volt Alert, sitting on the shelf near the driver, flashed Red. Further experimentation revealed that any movement of the chair on the plastic mat or any shuffling of my shoes as I pushed the chair from place to place would produce a flash on the Volt Alert when I touched the screw driver. Obviously the mat was producing a static charge capable of producing an EM field large enough to trigger the Volt Alert when discharged into the metal of the screw driver. This was very disturbing and I quickly reviewed in my mind the static sensitive components that might have been handled since the mat was purchased. Fortunately I have been preoccupied with some construction in the basement recently and had not set up any experiments since the mat was purchase.

 

      I am now sorry I bought the mat but thankful for the lucky chance revelation provided by The Fluke Volt Alert. I would say live and learn but there doesn't appear to be enough time in a lifetime to learn enough to prevent the side effects of decisions from getting me.

 

John

 

 

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  • John

    Lucky catch.

     

    What is the bottom of the chair made of.

    It seems to me it must be a very sharp metallic edge, in order to damage concrete....

     

    Mark

  • in reply to mcb1

    Hi Mark,

    The (4) wheels of the chair are made of hard plastic. What happens is that over time little bits of sand, dust, and concrete embed themselves in the plastic. These act like little chisels as the wheels roll across the surface and cut more material loose. If there is a weak point in the concrete a small hole begins to form and the impact of the wheel as it rolls through the pot hole just accelerates the failure. I have had this happen to me twice in areas where I work intensively over time. I will just have to put down some non-static producing flooring over the concrete.

    John

  • in reply to jw0752

    John

    All I can say then is your concrete must be low grade, or perhaps not as well polished.

    Here our floors are a minimum of 20MPa, and the surface is usually higher after polishing/finishing.

     

    There are "two pot" resin coatings that may help reinforce and smooth the surface.

     

    We coloured sections of our concrete floor and then cut it to look like tiles.

    The coating makes it shiny (with non slip added at the entranceways) and is nonmarking.

    The coating has lasted 8 years, but doesn't have a chair running over it ...

     

    If you use carpet there is an antistatic spray you can apply.

    Every few years they redo ours at work. ...usually after the controllers complain about getting zaps.

     

    Mark

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  • in reply to jw0752

    John

    All I can say then is your concrete must be low grade, or perhaps not as well polished.

    Here our floors are a minimum of 20MPa, and the surface is usually higher after polishing/finishing.

     

    There are "two pot" resin coatings that may help reinforce and smooth the surface.

     

    We coloured sections of our concrete floor and then cut it to look like tiles.

    The coating makes it shiny (with non slip added at the entranceways) and is nonmarking.

    The coating has lasted 8 years, but doesn't have a chair running over it ...

     

    If you use carpet there is an antistatic spray you can apply.

    Every few years they redo ours at work. ...usually after the controllers complain about getting zaps.

     

    Mark

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