“Compliance verification should be performed prior to each use (daily, shift change, etc.). The accumulation of insulative materials may increase the foot grounder system resistance. If foot grounders are worn outside the ESD protected area testing for functionality before reentry to the ESD protected area should be considered.” (ESD SP9.2 APPENDIX B - Foot Grounder Usage Guidance)
“A log should be maintained which verifies that personnel have tested their personal grounding devices.” (ANSI/ESD S20.20 Paragraph 6.2.2.2 Personnel Grounding Guidance)
“Frequency of Functional Testing: The wrist strap system should be tested daily to ensure proper electrical value. Nominally, the upper resistance reading should be < or = 10 megohms or a user-defined value.” (ANSI/ESD S1.1-2006 Annex A3)
Per ESD SP9.2 APPENDIX C - Parallel Ground Paths, “A parallel ground path allows a flow of electrical current through a path that is not intended for the test. Parallel ground paths may be caused by several different situations. For example:
a. The path represented by the person standing with one shoe on the floor and the other shoe on the test apparatus. A parallel path may be created by the shoe on the floor. Current from the test instrument is then directed down two paths when it was intended to be directed down one. The correct path for the test is with one shoe in the air or on an insulating surface and the other shoe on the test plate.
b. The path presented by a person inadvertently supporting themselves by means of one hand on another object such as a wall, table or supporting member in order to measure the resistance in one foot contact. The hand has created a parallel path to ground.
c. The path represented by a person leaning against another object with other parts of the body in order to provide physical support during a testing sequence. This can then lead to other grounding paths and erroneous results.”