ANSI/ESD STM7.1-2020 uses a two-stage voltage sequence for installed-floor resistance testing. Test voltage matters because some flooring materials give different resistance readings at different voltages. The prescribed sequence helps account for these differences when measuring electrostatic discharge (ESD) flooring resistance.
STM7.1-2020 is an ESD Association standard test method (STM) approved by the American National Standards Institute (ANSI). ASTM F150-25 is a test method published by ASTM International.
Which voltage to use and when to record the reading
Start at 10 volts
The acceptance procedures for resistance-to-ground and point-to-point testing in STM7.1-2020 sections 6.2.1.5 and 6.2.2.5 each begin with the measurement equipment set to 10 V and energized. If the indicated resistance is less than 1.0 × 10⁶ ohms, record the value after 5 seconds.
Switch to 100 volts at or above 1.0 × 10⁶ ohms
If the indicated resistance at 10 V is equal to or greater than 1.0 × 10⁶ ohms, the equipment is de-energized and re-energized at 100 V. At 100 V the resistance is recorded after 15 seconds or as defined by the meter’s electrification period. A reading of exactly 1.0 × 10⁶ ohms at 10 V is therefore measured again at 100 V.
Use the 100-volt reading after switching
If switching to 100 V results in a reading below 1.0 × 10⁶ ohms, the reading made at 100 V is the value used. De-energize the measurement equipment after recording the applicable reading.
Why testing starts at 10 volts
ASTM F150-25 Appendix X1.1: tile polarization
ASTM F150-25 provides background on its own test-voltage sequence in nonmandatory Appendix X1.1. It explains that testing begins at 10 volts DC (direct current) to avoid polarizing the tile and producing a false reading. This explanation concerns the F150 method for conductive and static-dissipative resilient flooring.
STM7.1-2020 Annex C: possible breakdown at 100 V or higher
The informative Annex C of STM7.1-2020 notes that, depending on the material being tested, 100 V or higher may cause a breakdown in the material. The breakdown creates a less resistant path that may not be indicative of the resistance of the flooring system and may give a misleading characterization of its triboelectric charge and discharge capabilities. Triboelectric charge is static charge produced when materials contact and separate.
Can the voltage change the reading?
For some materials, yes. The foreword to STM7.1-2020 notes materials that measure at or above 1.0 × 10⁶ ohms at 10 V but below 1.0 × 10⁶ ohms at 100 V. A lower 100 V reading alone does not establish that material breakdown occurred.
Frequently Asked Questions
For installed-floor acceptance measurements, STM7.1-2020 starts at 10 V. Below 1.0 × 10⁶ ohms, record after 5 seconds. At or above 1.0 × 10⁶ ohms, de-energize the equipment, re-energize at 100 V, and record after 15 seconds or the meter-defined electrification period.
For both installed-floor acceptance measurements under STM7.1-2020, use the 100 V reading even if switching to 100 V brings the result below 1.0 × 10⁶ ohms.
ASTM F150-25’s nonmandatory Appendix X1.1 explains that its test starts at 10 VDC to avoid polarizing the tile and producing a false reading. Separately, STM7.1-2020’s informative Annex C says that, depending on the material, 100 V or higher may cause breakdown and a less resistant path that misrepresents the flooring system. A lower 100 V reading does not by itself prove breakdown.