I was wondering why ANSI/ESD S20.20 table 3 has a requirement that the wriststap wristband exterior has to essentially be an insulator (>10^7 ohms). I asked Dave Swenson and he replied “The idea of an insulating exterior to a wrist strap goes back to the military requirement to remove watches and other jewelry from the hands and arms when working on electrical and other mechanical equipment where there is a physical risk of catching the hands and arms or contacting a metallic part the person is wearing to an energized source. In the Air Force, we removed rings and watches etc. when working on airplanes anywhere. Some of the early wrist bands for static control were standard metal expansion bands and these were viewed as being a hazard to people in electrical work. While it is necessary to provide grounding for personnel, having an insulating, or at least high resistance contact surface provided an element of risk reduction (not safety by the way- just a reduction of risk). The human skin still can accept a shock but the somewhat higher resistance band (exterior) does not become an added risk. The interior has to be pretty conductive to make good contact with the skin as skin electrical resistance varies substantially from person to person. The insulating exterior has been part of the plan for a long time and is still a good idea. Is it needed everywhere? Certainly not but has become an accepted practice - like wearing a seat-belt in the car and airplane”
I thought this would be good information to add to the forum in case anyone else may want to know.
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Greetings of the day to all from India
Thank you Andy Sir
Indeed a good information and good idea to put such information on the Forum platform .
Regards
Vijay