Glossary: Minimum Resistance

The ANSI/ESD S20.20 static control standards does not offer a minimum resistance reading. Strictly in terms of grounding static charges, any floor with a resistance <1 x 10E9 meets ANSI/ESD S20.20 and is considered acceptable.

While S20.20 does not specify a lowest acceptable resistance, for best practices the flooring industry has historically set the minimum resistance at no less than 2.5 x 10E4, or 25,000 ohms. This number was based on a defunct NFPA test method, requiring a resistance test with 500 volts of DC current applied to the surface of the flooring material. Current standard test methods apply much lower voltage and yield higher readings.

A floor measuring 25,000 ohms using the NFPA test method would yield a far lower resistance reading with less applied voltage.

ANSI/ESD standards do not offer a minimum resistance requirement because the built-in resistor in the ESD footwear required in manufacturing and handling spaces protects the wearer from potential electric shocks. In data centers, call centers, FAA flight towers, 9-1-1 dispatch centers, and other spaces where ESD-protective footwear is not required, materials with electrical resistance below 2.5 x 10E4 are considered a potential safety hazard.

For this reason, telecom and Federal Aviation Administration standards prohibit the use of flooring materials with resistance below 1 x 10E6 in spaces where energized equipment is used.

A split illustration demonstrating an issue with highly conductive floors. On the left side a data server is shown with the door open and a zoomed in cross section shows a split wire (labeled "Faulty wiring or short circuit". On the right side, a worker is shown reaching out to the data server. A yellow and red line running down her arm to ground shows the charge being carried. Text underneath reads "If direct body contact is made with an electrically energized part, while similar contact is made with another conductive surface (... at a different electrical potential), a current will enter the body at one contact point, traverse the body, and exit at the other contact point (usually the ground). Each year many employees suffer pain, injuries, and death from such electric shocks" attributed to OSHA. The source is given as "How Electrical Current Affects the Human Body," OSHA (Occupational Safety and Health Administration) website: (http://www.osha.gov.uk/SLTC/etools/construction/electrical_incidents/eleccurrent.html)
A split illustration demonstrating an issue with highly conductive floors. On the left side a data server is shown with the door open and a zoomed in cross section shows a split wire (labeled "Faulty wiring or short circuit". On the right side, a worker is shown reaching out to the data server. A yellow and red line running down her arm to ground shows the charge being carried. Text underneath reads "If direct body contact is made with an electrically energized part, while similar contact is made with another conductive surface (... at a different electrical potential), a current will enter the body at one contact point, traverse the body, and exit at the other contact point (usually the ground). Each year many employees suffer pain, injuries, and death from such electric shocks" attributed to OSHA. The source is given as "How Electrical Current Affects the Human Body," OSHA (Occupational Safety and Health Administration) website: (http://www.osha.gov.uk/SLTC/etools/construction/electrical_incidents/eleccurrent.html)
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Background graphic is a still from the StaticWorx GroundSafe ESD Flooring – Your Trusted Partner explainer animation. In the foreground at the bottom are two boxes. The top is a bright blue with the StaticWorx logo and "GroundSafe ESD Flooring" underneath in white. The second is a dark blue-gray and includes the text in white: “GroundWorx ESD Flooring – Your Trusted Partner”
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StaticWorx high-performance static-control floors protect electronic components, explosives, and high-speed computers from damage caused by static electricity. ESD flooring is part of a system. Choices should always be based on objective, researched evidence. When you partner with us, we look at all possible items that may need to integrate with the floor, and, focusing on your goals and objectives, help you find the right floor for your application.