ANSI/ESD STM97.1-2025 measures electrical resistance through a person wearing footwear or foot grounders while standing on a flooring system. It provides different procedures for evaluation before installation, new footwear on a previously qualified installed floor, and installed floors without prior evaluation or a known history.
Craftsman Concrete helps facility ESD program teams identify the evaluation needed, coordinate testing responsibilities and review the resulting qualification and closeout documentation. Person–footwear–flooring measurements are identified separately from floor-only resistance testing.
What STM97.1 measures
The person stands on the flooring and holds an electrode connected to the resistance meter. The measurement includes the person, footwear or foot grounders, and flooring together.
The method is intended for systems with total resistance below 1.0 × 10^9 ohms. That intended measurement range does not, by itself, establish that the facility’s qualification requirements have been satisfied.
STM97.1 covers flooring systems used to control electrostatic charge, including mats, floor coverings, coatings, paints and floor finishes. Its scope excludes uses involving electromagnetic interference, ordnance, flammables and explosives.
Choose the procedure for the installation and footwear
| Testing situation | Procedure and supporting guide | Test environment |
|---|---|---|
| Evaluating a flooring system before installation | Section 6.1: pre-installation qualification | Controlled conditioning of the footwear and flooring samples |
| Evaluating a new footwear type on a previously qualified installed floor | Section 6.2: new footwear on an existing floor | Ambient temperature and humidity |
| Evaluating a newly installed floor not assessed under section 6.1, or an existing floor with unknown history or manufacturer | Section 6.3: installed-floor evaluation | Ambient temperature and humidity |
The STM97.1 procedure-selection guide explains the distinctions, including when additional footwear types can be evaluated under section 6.2 after an initial section 6.3 evaluation.
Preparation depends on the procedure
Representative samples before installation
Section 6.1 evaluates representative flooring samples, referred to as specimens in STM97.1. They must include the components as they will be used in the installation, including applicable adhesive, grounding and substrate materials.
The evaluation includes floor-resistance baseline measurements before measuring the person, footwear and flooring together. Follow the electrode locations prescribed in STM97.1 Figure 1 and the incorporated STM7.1 procedure.
Controlled conditioning versus ambient testing
After cleaning, section 6.1 requires at least 72 hours of preconditioning at 12% ± 3% relative humidity and 23 °C ± 3 °C. The footwear and flooring samples remain in that environment until testing is complete.
Sections 6.2 and 6.3 use ambient temperature and humidity. That does not remove the need to follow the specified cleaning procedures or consider moisture introduced during cleaning.
The moisture and conditioning guide explains these requirements and why some moisture-sensitive materials may take longer than 72 hours to reach equilibrium.
Measure both feet and each foot separately
All three procedures record resistance with:
- Both feet contacting the flooring.
- Only the left foot contacting the flooring.
- Only the right foot contacting the flooring.
The required repetitions depend on the procedure, including the footwear pairs, flooring samples, groundable points or installed-floor locations being evaluated.
The test footwear is worn on both feet for at least ten minutes before measurement to establish moisture equilibrium. The footwear wear-in explanation describes that requirement.
Follow the selected procedure’s connections, voltage sequence, reading times and repetition instructions.
Verify the equipment and protect the person being tested
Use apparatus meeting the applicable requirements in section 5.
STM97.1 recommends verifying the complete measurement setup under Annex A before section 6.1 measurements. Before sections 6.2 and 6.3, it recommends verifying the meter and test leads under Annex A.1. It also recommends evaluating the footwear/person system under Annex C before each procedure.
The measurement-setup verification guide explains the equipment checks.
Follow equipment grounding instructions and applicable personnel-safety requirements. Resistance results from STM97.1 must not be used to determine the relative safety of personnel exposed to high AC or DC voltages.
Report the combination and conditions actually tested
The reports identify the method, footwear, flooring system, testing organization, measurement equipment, completion date, temperature and relative humidity.
The required resistance records differ by procedure:
- Section 6.1: floor-resistance baseline readings, person-system measurements, specified resistance summaries and conditioning time.
- Section 6.2: all nine resistance values from three footwear pairs, covering both feet, the left foot and the right foot.
- Section 6.3: all measured data points and the specified minimum and maximum values, reported separately for both feet, the left foot and the right foot.
STM97.1 also recommends recording setup-verification data, sock composition, measurement voltage and the equipment calibration due date.
How the result supports S20.20 qualification
For a footwear/flooring system used for personnel grounding, S20.20-2021 requires both system resistance below 1.0 × 10^9 ohms under STM97.1 and peak body voltage below 100 volts under STM97.2.
The resistance result therefore supplies one part of the qualification evidence. The S20.20 footwear/flooring qualification guide explains the combination-specific requirements, conditioning and supporting records.
Frequently asked questions
No. It measures the electrical resistance of a person wearing footwear or foot grounders while standing on the flooring. The pre-installation procedure also includes separate floor-resistance baseline measurements, but those do not replace the person-system measurements.
No. Section 6.1 addresses pre-installation evaluation. Section 6.2 evaluates new footwear on a previously qualified installed floor, and section 6.3 evaluates installed floors without the specified prior evaluation or a known history.
No. S20.20-2021 requires both the STM97.1 system-resistance result and the STM97.2 body-voltage result for each footwear and flooring type combination used for personnel grounding. The qualification evidence must also meet the applicable conditioning and record requirements.