FAQ: Why should the adhesive be more conductive than the ESD flooring material?

In any ESD flooring installation we need to look at several factors.

  1. Does the floor meet ANSI/ESD or ATIS grounding requirements?
    To meet ANSI/ESD S20.20, resistance should measure below 10E9.
    To meet ATIS, resistance should be 10E6 or above.
  2. Is the system inherently or potentially unsafe due to electrical safety issues, such as over conductivity, improper installation or misapplication?

The first variable we investigate is what we call system resistance. System resistance is the ohms resistance of the floor, the adhesive and the ground connection. System resistance will always measure equal to or greater than the most resistant—least conductive—component in the chain.

Graphic labeled “System Resistance to Ground”. The illustration below shows a woman (labeled “Person wearing ESD shoes”) holding a wand (labeled “Metal want”). The floor beneath her has the ground symbol extending from it and is labeled “Grounded ESD floor”. The metal wand is connected to an ohmmeter (labeled “Wide ranging ohmmeter”). The ohmmeter also has a connection to ground.
Graphic labeled “System Resistance to Ground”. The illustration below shows a woman (labeled “Person wearing ESD shoes”) holding a wand (labeled “Metal want”). The floor beneath her has the ground symbol extending from it and is labeled “Grounded ESD floor”. The metal wand is connected to an ohmmeter (labeled “Wide ranging ohmmeter”). The ohmmeter also has a connection to ground.

Important: To direct all electricity downward to ground, as intended, the adhesive must be the most conductive (least resistant) element in the flooring system.

The flooring surface should always most resistant (lease conductive) component in the system.

Using an adhesive that’s not conductive or is less conductive than the flooring material could pose a safety hazard.

Conductive floor and less conductive adhesive
Conductive floor and less conductive adhesive

If the adhesive is not conductive, or the adhesive underlayment is less conductive than the flooring material, electrical charges could bypass the adhesive, preferring the less resistive route, across the top of the floor—to the chassis of energized equipment, for example, or grounded electrical consoles, or the frame of a large UPS (uninterruptible power supply) in a data center.

Note to specifiers: A simple audit with an ohm meter can expose this potential problem. We suggest that the flooring material be tested for point-to-point resistance—across the same floor tile. This will indicate whether or not the surface of the flooring material falls within the proper resistivity range.

After the flooring is installed, to verify that it’s properly grounded, test point-to-ground resistance—that is, from the tile to the copper ground strip, or whatever attachment was used to ground the floor.

Resistance Test - Point-to-Point Rtt
Resistance Test - Point-to-Point Rtt
Fast Charge
If the floor is more conductive than the underlying adhesive, charges may remain on the surface of the floor, creating a potential safety hazard.

Remember: system resistance is always equal to or greater than the most resistive element in the chain—so an adhesive that’s not conductive or is less conductive than the flooring material will raise the overall system resistance.

If point-to-point resistance is lower than the point-to-ground resistance—which, again, would happen if the adhesive were not as conductive as the tile—there may be cause for safety concerns.

For this reason, it is best to install tiles with a point-to-point resistance above 100,000 (1 x 10E5) ohms.

Remember: system resistance is always equal to or greater than the most resistive element in the chain—so an adhesive that’s not conductive or is less conductive than the flooring material will raise the overall system resistance.

Fast Charge
If the floor is more conductive than the underlying adhesive, charges may remain on the surface of the floor, creating a potential safety hazard.

 

If point-to-point resistance is lower than the point-to-ground resistance—which, again, would happen if the adhesive were not as conductive as the tile—there may be cause for safety concerns.

For this reason, it is best to install tiles with a point-to-point resistance above 100,000 (1 x 10E5) ohms.

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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.