Our company uses PVC permanent antistatic flooring with a specification of 60cm*60cm. We have established a company policy of conducting a point-to-point grounding resistance test every 6 months. However, we have encountered difficulties in selecting the inspection points as there are a large number of them, and it is not feasible to inspect all of them. Many equipment and workbenches obstruct the inspection, and the workload is significant. Therefore, we would like to inquire if the ESD Association has any recommended inspection areas and intervals.
Are there any recommended standards or methods for defining the inspection interval for each type of antistatic item?
Furthermore, regarding the combination of antistatic flooring and shoes, we checked the system resistance and walking voltage during product certification. However, we did not check the walking voltage during conformity verification, which was recorded as “NC” by a third-party audit organization. Is this “NC” correct?
In ANSI/ESD STM7.1 - Flooring, for installed floors the standard test method states, Perform a minimum of five tests (in different locations) per contiguous flooring system area or a minimum of five tests per 500 square meters of flooring system area, whichever is greater. While this is a recommendation, what is important is to generate data to support the compliance verification procedure. The user is really allowed to choose what points to measure and how many. Every tile does not have to be tested, and floor under equipment may not have to be tested at all. If the floor is used as the primary grounding system for personal, then the test points should be chosen where the people are walking.
As for the NC, if you look at table 2 in ANSI/ESD S20.20 - 2021, product qualification requires both resistance testing and body voltage. Compliance verification is a systems resistance check and a resistance to ground of the floor. There is no requirement for a body voltage test. There is a footnote that recommends a periodic body voltage test but it is not a requirement.
I hope this helps.