ESD Systems - Questions And Answers

Our existing heel strap tester has problems testing when operators wear leather shoes. Is it our tester that is not good? Or a shoe issue? –Michael Walsh, Datel, Mansfield, MA

The problem is dependent on both the tester and the operator. I am making the assumption that the problem that arises when wearing leather shoes while testing their heel straps is a fail low condition. If this is so, then what is happening is that the leather shoes are becoming too conductive by means of moisture (inside the shoe or out). The connection from the heel strap to the body is bypassing the conductive tab which has a 1 megohm resistor in series with it and coupling directly with the foot to the outer soul at a resistance much lower than 1x10^6 ohms. This will cause a fail low condition.To correct this, the operator will need to wear different shoes. The concern here is that the operator may be too conductive if they were to come into contact with a live wire (<250 VAC) and run the risk of carrying to much current in their ground path (because the current limiting resistor was bypassed).

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