Definition of ESD flooring: “An ESD Flooring system serves as a conduit for an electrical static charge (known as BVG or Body Voltage Generation accumulation on a person from movement across a surface) to discharge to a desired controlled ground point.” – PI Industrial
Some surfaces like concrete or vinyl floors may provide anti-static properties under the right conditions, and thus potentially considered anti-static flooring. Yet, non-treated floors or even static coated floors (see below) do not provide controlled dissipation or grounding of triboelectric charges. Therefore, the difference between anti-static flooring and ESD flooring is significant. Insulative materials are not considered anti-static.
Anti-static flooring reduces, removes, or prevents the buildup of static electricity. Therefore, ESD flooring systems fit into this definition, but the terms are not interchangeable. While some materials can provide less charge buildup when used for flooring, dedicated static control flooring systems require a connected ground so that charges can dissipate safely.
ANSI defines “Static Dissipative” as anything with a resistance between 1 Million (106) Ohm’s and 1 Billion (109) Ohms. Tile-to-tile systems of rubber sheeted variations to ensure a continuous static dissipative service throughout the space.
ANSI Defines conductive flooring resistance as LESS THAN 1 Million (106) Ohms. Conductive flooring systems provide the lowest charge generation and quickest charge dissipation for an ESD production environment. The flooring is grounded through a copper strip which connects to the flooring to a grounded connection such as a wall outlet. One copper grounding strip is required for every 1000 sq. ft. of ESD flooring.
Electrically conductive flooring is sometimes referred to as anti-static conductive flooring, defined by an electric resistance of between 10^4 and 10^15 ohms.
ESD flooring has multiple construction and configuration options, each of which varies in price, anti-static properties, and conductivity including:
The shock generated by touching a doorknob after walking across a carpeted floor in socks is about 25X as strong as the shock needed to spark most vapor or gas clouds. For humans to feel the effect of static electricity, the discharge must reach at least 3500 volts, while as little as 20V could damage sensitive electronics and charges beyond 1400V could set off an explosion. Therefore, any charges generated by walking through ESD hazard areas must be neutralized as quickly as possible. Superconductive flooring would be found in places like munitions plants and warehouse, chemical processing, and fireworks production. Importantly, highly conductive mats increase the risk of electrical shock for the operator when used in conjunction with high voltage equipment.
Non-conductive or insulative mats and floor runners, also known as switchboard mats, use insulative materials that prohibit the flow of electricity and prevent deadly shocks. They are often used as localized workstation mats. The dialectic strength provides an insulative foundation for workers exposed to high voltage equipment of up to 50,000V.
For more information about ESD epoxy and other static-free floor coatings, read here.
ANSI/ESD S20.20 is a process based document which provides parameters for a standard set of test methods for evaluation of ESD safety. These three segments define the conductive flooring specification
“ANSI 20.20 ESD calls for a combined resistance of the floor AND the person (cumulative) to have a resistance LESS THAN 35 Million Ohms. This is somewhere between 10,000,000 (107) Ohms and 100,000,000 (108) Ohms. Electrical Safety Standards call for the floor to have a resistance of NO LESS than 25,000 (between 104 and 105) Ohms. So now we have narrowed our range down to 104 to 108 Ohms. Throw in some safety margins and we can narrow it down to 105 and 107 Ohms. Now we have a tight specification we can test for and clearly establish as PASS/FAIL for our flooring.” – Safteng.net
You can learn more about the process of installing conductive sheet flooring in the video below.
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