ESD floor compliance parameters per S.20.20

Technical Questions
#1

Sir,
For an ESD safe floor to be compliant to S.20.20.2014 at 12%+/-3 and temperature 23^0 C +/- 3
Is the maximum acceptable Point to Point ( surface ) resistance ( RPTP / SR) to be < 1 x 10^9 ohms @ 100v test ?

                         Point ( surface )  to  ground  point  resistance  (RTG/SGR)           to be < 1 x 10^9 ohms @ 100v test   ?

{Some time back, from some document I had read it as under .( I do not remember from where)
( RPTP / SR) 1.1 x 10^7 to 5.5 x 10^9 ohms @ 100v test }
(RTG/SGR) 1.1 x 10^6 to 8.5 x 10^8 ohms @ 100v test }

And , is the acceptable Person to Ground (PGR) in junction with ESD footwear & ESD floor
to be <1 x 10^9 ohms or 35 x 10^6 ohms @ 100v test } ?

Are my understanding okay ? please clarify and correct me ?

#2

Hello and thanks for your question.

Let’s separate some of the requirements. For an floor to be compliant with ANSI/ESD S20.20 it must have a point to point and point to groundable point of less than 1x109 ohms for product qualification. This shall be done at 12% Rh and 23C.
The compliance verification limit shall be resistance to ground of less than 1x109 ohms when tested in ambient conditions.

If the floor is part of a flooring/footwear system to ground personnel then an additional test to measure body voltage is required. The body voltage shall be less then 100 v during while walking on the floor with the defined footwear.
This is in the current 2014 specification. In the previous specification, 2007, it was allowed that if the system resistance of the person, footwear and floor measured less than 3.5x10*7 ohms, a body voltage test was not required. This was removed from the 2014 specification based on published work done by several people.

As far a test voltage, for measurements less than 1x106 ohms the test voltage is 10 volts. If the resistance is greater than 1x106 ohms switch to 100 volts and test. What ever the 100 volt reading is after the 10 volt test is done is the reported resistance.

#3

Sir,
Thank you for clarifying the doubts as it had developed some confusions against some other information I had seen some time back some where.
Now the system resistance of the person, footwear and floor is < 1x 10^9 ohms is it ? Not 35 mega ohms is it correct ?
But only foot wear testing with footwear tester it should be 35 mega ohms or
100 mega ohms ?

Regards

#4

The entire system, person, footwear and floor need to measure less than 1x10*9 ohms from the persons hand to ground. The higher resistance with the data that shows less than 100 volts body voltage will comply with the standard.
As a best practice, set the compliance verification limit to slightly above the qualification limits that were found for the floor and footwear. If a measurement is over that limit, the body voltage should be checked again. A user can set the compliance verification limit to anything lower than the limits in ANSI/ESD S20.20.

#5

Thank you Sir for your valuable guidance

Regards