Under ANSI/ESD STM7.1-2020, testing an electrostatic discharge (ESD) floor tile by itself does not qualify the complete adhesive-installed flooring system. The test sample (referred to as a specimen in STM7.1) must include the tile, appropriate adhesive, grounding system and substrate (the underlying surface to which the flooring is applied) intended for the installation. It must also include a seam whenever the installed flooring has seams. Testing the assembled system accounts for interactions between these materials that can affect its electrical resistance.
STM7.1-2020 is an ESD Association standard test method (STM) approved by the American National Standards Institute (ANSI).
What the qualification sample must include
All components of the intended installation
Section 6.1.2.2.2 of STM7.1-2020 requires the flooring sample to represent and include all system components as they would be used in an installation. For an adhesive-installed tile system, this includes:
- The tile
- The appropriate adhesive
- The grounding system
- The substrate intended for the installation
Testing the tile by itself omits the other components that form the intended flooring system.
Two groundable points
Section 6.1.3.3 of STM7.1-2020 requires each flooring sample to have two groundable points that simulate the grounding methods used in the intended installation.
A seam whenever the installed flooring has seams
Section 6.1.2.2 of STM7.1-2020 requires the test sample to include a seam whenever the installed product has seams.
Why the assembled system is tested
The foreword to STM7.1-2020 explains that interactions among the materials in a flooring system can affect its overall measured resistance.
The standard’s informative Annex B gives an example. A glue-down tile with resistance below 1.0 × 10⁶ ohms, characterized as conductive, could be installed with an adhesive having resistance of at least 1.0 × 10⁶ ohms. The resulting system would have resistance to ground of at least 1.0 × 10⁶ ohms, characterized as dissipative rather than conductive.
This example describes a possible system effect, not a certainty for every tile and adhesive combination.
The informative Annex B also notes that the substrate’s moisture or mineral content can change adhesive resistance and, in turn, flooring-system resistance, especially when the adhesive is the main controlling element.
Frequently Asked Questions
No. Under ANSI/ESD STM7.1-2020, the qualification sample must represent the intended installation and include its components. For adhesive-installed tiles, that includes the tile, appropriate adhesive, grounding system and substrate. Each sample must also have two groundable points that simulate the intended grounding methods.
The sample must include a seam whenever the installed flooring product has seams.
The materials combined in the flooring system can interact and affect its overall measured resistance. STM7.1-2020 therefore tests the assembled system. A conductive tile tested by itself does not guarantee that the complete flooring system will be conductive.