Desco - Questions And Answers

It is my understanding that dissipative floor mats must be grounded [at] 6 foot intervals. But, conductive floor mats can be grounded at 12 foot intervals. And, if that is true, can a 24 foot long mat be grounded at each end or must the grounding points be 12 feet from each grounding point? - Daniel Taylor, Exide Electronics, Leland, NC

If you only wanted to use two ground cords on a 24 foot conductive mat (< 1E4 Ohms) then the recommendation would be to ground every 8 feet rather than at each end. This divides the mat up into 3 equal parts, further minimizing the possibility of two points having a significant potential difference. The real test is to measure the voltage on the body while walking across the grounded mat; as long as the person is grounded via conductive foot wear to the mat, they should be at ground potential (0 volts). The goal for grounding conductive mats (either electrically dissipative or conductive) it to ensure the surface is at the same potential at any given point. The more resistive a material is, the longer it takes to bring to equilibrium a potential difference on the surface.

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