12 volt access keypads shocking people

[wiredoc]

Out of the thousands of keypads we install, maintain,and troubleshoot, about 6 are getting complaints of being shocked.
I immediately thought of static,because they are in their cars. The keypads are attached to a 10"×1/4" steel bollard. They're sunk 2' in the ground and surrounded by 2' sqare and deep of concrete.
Double, triple grounded it,but no success.


Any ideas?

 

[GoldDigger]

It is, IMHO, one hundred percent certain that it is static. Perhaps related in some way to the pavement and other conditions as the cars approach the keypad.

If it were foreign voltage of any sort on the keypad, you would be able to measure it relative to local or remote ground.

If people were standing on dirt or concrete next to the bollard, then there would be a possibility that there was a step potential in the earth surrounding the bollard because of fault current in the earth for some reason. But if they are in a car that would not be noticed and would not cause a "shock".

Is it a single spark at first touch? Or is it a repeated sensation for as long as they are in contact with the keypad?

 

[brantmacga]

12 volt access keypads shocking people

Are you measuring any voltage at the keypad?

I had this happen once (it was a Detex alarm shocking people when they put the key in), and read a small amount of voltage, and only after it rained.

Found a cracked section of conduit underground about 5' away, and the insulation had deteriorated off the conductors. I had kneeled down on the ground while looking for the source and it knocked the piss out of me when I touched the concrete sidewalk.


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[kwired]

Not necessarily a permanent solution, but water down the driveway to see if that helps, it should lower static charge on vehicles as they approach if that is the problem.