Conformity Magazine - December 2007 - (Page 19) ESD Open Forum have to be <1 x 109 ohms. ANSI/ESD S6.1 – Grounding is a good reference tool to assist with all the associated grounding issues. A third test measures the resistance of a person to ground while standing on the floor. ANSI/ESD STM 97.1 – Floor Materials and Footwear – Resistance Measurement in Combination with a Person measures how the floor will actually drain static charge from a person. This test procedure helps to evaluate not only the floor, but the footwear used by personnel as well. The S20.20 specification is <35 megohms using this method. To comply with the S20.20 requirement, the floor just about has to be in the 107 ohms to ground range. A fourth test measures the voltage generated by personnel as they walk on the floor. The test method is ANSI/ESD STM97.2 – Floor Materials and Footwear – Voltage Measurement in Combination with a Person. This test method requires an instrument called a charged plate monitor (CPM) – available from several ESD material and equipment suppliers. The voltage generated should be <100 volts when people walk on the floor. It is advisable do this test with the current floor before applying wax to determine a base line. ANSI/ESD S20.20-2007 states that a floor and footwear grounding system for people must have a resistance to ground <1 x 109 ohms and a voltage on personnel of <100 volts. ■ About the Author David E. Swenson is President of Affinity Static Control Consulting, L.L.C. He is currently serving as Sr. Vice President, President-elect for 2008 and Professional Certification Chair in the ESD Association. He can be reached at 512-244-7514 and at inquire@affinity-esd.com . About the ESD Association Founded in 1982, the ESD Association is a not-for-profit, professional organization directed by volunteers dedicated to furthering the technology and understanding of electrostatic discharge. The Association sponsors educational programs, develops ESD standards, holds an annual technical symposium, and fosters the exchange of technical information among its members and others. Additional information may be obtained by contacting the ESD Association, 7900 Turin Rd., Bldg. 3, Rome, NY 13440-2069 USA. Phone: 315-339-6937. Fax: 315-339-6793. Email: info@esda.org. Website: http://www.esda.org. across the floor in enough places to ensure that the floor coating is uniform. Five to ten measurements in a room of the size mentioned in this question (1,600 square feet) would be sufficient. In the second test, place one electrode on the floor and connect one lead from the meter to the electrode. Connect the other lead from the test meter to a ground point and measure first at 10 volts and then at 100 volts if over 1 x 106 ohms. To qualify as an ESD protective floor per ANSI/ESD S20.20 – ESD Association Standard for the Development of an Electrostatic Discharge Control Program for – Protection of Electrical and Electronic Parts, Assemblies and Equipment (Excluding electrically Initiated Explosive Devices), the resistance will © Photographer: Bobbie Sandlin | Agency: Dreamstime.com DECEMBER 2007 CONFORMITY 19 http://Dreamstime.com http://www.esda.org
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