Static Electricity Professionals

Mission Critical Anti Static Flooring for Public Safety Emergency Communications Applications: Which Resistance Range is Correct – Static Dissipative or Conductive?

 Understanding Grounding Standards: Motorola R56 and ATIS-0600321-2010

Unnecessary confusion exists over which ohms resistance rating is correct for grounded static control flooring used in end user operational equipment environments. The root cause of this confusion is the misapplication of flooring requirements used in electronics manufacturing and explosives handling with the recommendations of compliance/standards organizations overseeing telecommunications and data center environments. The purpose of this post is to clear up this confusion by providing information and links to appropriate industry resources and standards organizations. (Please note: ESDA document ANSI/ESD S20.20-2007 is not referenced.  S20.20 is intended for program managers involved with the design and implementation of a static control process in ESD protected areas as part of a comprehensive program in electronics manufacturing environments.) This article focuses on non-factory, end user operational equipment concerns like networked offices, data centers and emergency dispatch call centers.

  During research for an article to be published by The Construction Specifier in their September issue, we examined FAA, telecommunications and computer industry grounding, lightning, electrical surge and safety standards. The research yielded information that lays to rest outdated assumptions about the proper electrical specifications of floors – particularly carpeting - installed in environments where static sensitive operational equipment is used. Many ESD flooring distributors incorrectly assumed that conductive flooring measuring between 2.5 X 10 E4 and 1.0 X 10 E6 was acceptable for end user environments. This static prevention strategy was borrowed from unrelated requirements involving the mandatory use of conductive flooring when handling explosives and flammable materials. This assumption and the applicability of explosives grade flooring for installation in end user environments – spaces often accessible to the public - is incorrect and poses unnecessary risks. Conductive flooring does not comply with the pertinent grounding standards for telecommunication equipment end user spaces. According to five different authorities/standards organizations, there is consensus in the recommended ohms resistance range for the type of flooring discussed here. The overlap or consensus opinion consists of a recommended ohms range above 1.0 X 10 E6 and below 1.0 X 10 E9 for end user spaces like server rooms, 911 call centers and data centers.

Specifically we looked at standards and recommendations from the following organizations:

 Link to IBM site recommendation and physical planning

IBM's Recommended range of flooring 1.5 X 10 E5 – 1.0 X 10 E10 ohms

A common document referenced by data center designers

 

Motorola R56: The Motorola guidelines have become the recognized standard in the industry and serve as the most complete and rigorous specification for the protection of communication system equipment installed at public safety and commercial wireless communication sites

Link to Motorola R56 See pages 468-470

Excerpt from Appendix C 3.3 of 2005 - 68P81089E50-B
9/1/05 — UP Version:

"Carpeting or floor tiles within an equipment room or dispatch center, including raised flooring, should have a resistance to ground measurement of between 106 and 109 ohms when measured using the test method of ANSI/ESD STM7.1-2001 or later"

 A new revision will be coming soon. This information was provided directly to Staticworx by the current working R56 committee.The excerpt from the new version is pasted into the bottom of this post

This standard should be cited when defining grounding parameters in public safety 911 communication centers

 

Alliance for Telecommunications Industry Solutions (ATIS) ATIS-0600321-2010

ATIS publishes standards for the information, entertainment and communications industries 

Electrical Protection for Network Operator-Type Equipment Positions

Link to ATIS-0600321-2010  Protection for Network Operator-Type Equipment Positions

Available for purchase: Digital Edition available from www.engineers.ihs.com

 Excerpt: Page 5, Section 4.2 Flooring

"Any carpeting or floor tiles should have a resistance to ground between 10 E6 and 10 E10 ohms when measured using the method of ESD-S7.1."

A telecommunications standard overseen by most telecommunications manufacturers

Applicable to numerous environments

 

Link to FAA STD 019e Lightning and Surge Protection, Grounding, Bonding and Shielding

Section 4.1.3.4.3.5 Static Dissipative ESD Floor Coverings

Recommended range of flooring 1.0 X 10 E6 – 1.0 X 10 E9 ohms

The 019e document supersedes a previous document (019d) where conductive flooring was considered acceptable.

 

Requirements for the Design of ICT Rooms - Best Practice Document

European Requirement

Recommended range of flooring 1.0 X 10 E6 – 1.0 X 10 E7 ohms per a European resistive properties test method.

Section 3 – Subsection 9 General Requirements

 

As you review these organization’s recommended parameters keep in mind 3 factors:

1.   Research has shown that conductive flooring offers no advantage over static dissipative flooring in end user environments.  

2.   When evaluating the ohms ratings, keep in mind that the difference between each ascending exponent is a factor of 10.  For example 1.5 X 10 to the 4^th = 15,000 ohms --- 1.5 X 10 to the 5^th = 150,000 ohms

3. A floor measuring between 2.5 X 10 E4 and 1.0 x 10 E6 is defined as a conductive floor. A floor measuring between 1.0 X 10 E6 and 1.0 X 10 E9 is defined as a static dissipative floor.

 Addendum: As part of our research we contacted a member of the Motorola committee overseeing Motorola R56. The purpose of contact was to determine if Motorola might be expanding their electrical resistance range for acceptable static control carpet. The published range since 2005 has been 1.0 X 10 E6 to 1.0 X 10 E9 ohms. There is currently a new draft of R56 in the works. As with other grounding and electrical standards organizations like ATIS and FAA 019e, we were told that Motorola’s acceptable resistance range will remain in the static dissipative range from 1.0 X 10 E6 to 1.0 X 10 E9.

Below is an excerpt of the flooring section as it will appear in the new draft:

Motorola R56 Appendix C

PROTECTING AGAINST ELECTROSTATIC DISCHARGE (ESD) IN EQUIPMENT ROOMS AND DISPATCH CENTERS

C.3.3 FLOORING

Carpeting or floor tiles within an equipment room or dispatch center, including raised flooring, should have a resistance to ground measurement of between 106 and 109 ohms when measured using the test method of ANSI/ESD-S7.1-2005 or later. Existing flooring that does not meet this requirement should be treated with a topical solution such as an antistatic floor wax or spray solution. The effectiveness of antistatic solutions is temporary and varies with floor material and relative humidity. Flooring resistance should be monitored every two weeks minimum to verify conformance to the above requirements. See ATIS-0600321.2010, section 4.2 and ANSI/ESD-S7.1-2005 for more information.

When ESD protective flooring is used, the following should be observed:

• ESD protective flooring shall be installed per the manufacturer's recommendations.

• ESD protective flooring and floor coverings should be installed, grounded, and tested by trained installers.

• Personnel entering the equipment room or dispatch area should wear ESD dissipative footwear or dissipative foot straps. The footwear should provide dissipative resistance values of less than 3.5 ´ 107 ohms as measured according to the measuring requirements within ANSI/ESD STM97.1-2006 or later. The footwear should also provide dissipative resistance values of less than 1.0 ´ 109 ohms as measured according to the measuring requirements of ANSI/ESD STM97.1-2006 or later.

 When ESD protective flooring is not installed at a dispatch position or equipment room, an ESD protective floor mat should be installed at the work areas. When ESD protective floor mats are installed, the following should be observed:

• The floor mat should provide dissipative resistance values between 106 and 109 ohms when measured using the test method of ANSI/ESD-S7.1-2005 or later.

 

Next blog:

We will investigate the grounding parameters required by medical electronic manufacturers for end user clinical environments.

 

How to discuss and recommend the right static control flooring with a client

A guide for architects working within client environments and applications that require conductive flooring

I recently visited with an architect who asked me how to best discuss and guide a client interested in using static control carpet in their application and environment.

There are two main question areas to begin the client discussion and help determine the right static control flooring recommendation:

1. What is the electronic industry supplier environment? Are they actively handling static sensitive electronic parts and sub-assemblies (as opposed to using them)?
   
2. What is the end user environment? Is the organization reliant on electronic systems that may be affected by static discharge events?

Specifying for electronic industry supplier environments handling static sensitive electronic parts and sub-assemblies

Electronic industry supplier environment organizations make, handle, test, store and repair electronic parts. A static event in these types of spaces would damage or destroy the part, assembly or final system. Grounding is achieved by wearing conductive heel straps or special shoes in conjunction with a grounded static control floor. In other words, personnel need to be grounded in any operation in this environment.

Generally, organizations handling and producing static sensitive parts designate certain areas as “ESD safe areas” or static free zones; an ESD safe area requires vigilant compliance with personnel grounding procedures as well as numerous other protocols for preventing the generation and accumulation of static electricity. The processes in these environments are usually governed by international standards like ANSI/ESD S20.20-2007.

Best flooring solutions for electronic industry supplier environments

Staticworx works with the architect to help narrow down which flooring to specify for the client for this type of application:

• EC ESD Rubber
• ESD Carpet Tile
  (not the same as low kV or computer grade carpet)
• ESD Vinyl Tile
  (Also called static conductive and static dissipative tile)
• Conductive Epoxy Coatings

For more information on conductive flooring solutions for electronic industry supplier environments, read the article, “Taking the Mystery Out of Selecting ESD Flooring” which is part of the Staticworx Knowledge Center.

Specifying for electronic industry end user environments: operations reliant upon electronic systems

The term “reliant upon electronic systems” means that the operation does not involve active handling, testing or assembly of electronic sub assemblies. These operations are electronic systems end user environments requiring sophisticated electronic equipment to accomplish their mission.

These spaces are often called Mission Critical Environments: examples include data centers, R & D labs, 9-1-1 call centers, hospital ERs, MRI suites, communication centers, flight towers, control rooms. These spaces utilize operational electronic systems which are manned by personnel who will not use special footwear. A static problem in these spaces would lead to an event that would impact either the equipment, operational mission or both. Examples of these types of problems include: data corruption, system lock-up, dropped phone call, unintended signals in a system.

In these applications, the static control floor must be fault tolerant. (See my recent blog entry on fault tolerant design.) The flooring must prevent the generation of static without the added benefit of special footwear; conversely the anti static floor must prevent static despite the use of static generating footwear.

Best flooring solutions for electronic industry end user environments

Most static control flooring will not inhibit static without the use of special footwear. That said, there are two flooring materials that perform very well despite this obvious deficiency and that Staticworx recommends for electronic industry user environment applications:

• EC ESD Rubber
  (with carbon chip conductors)
• ESD Carpet Tile
  (with conductive fibers wrapped around nylon tuftsand conductive backing.
  Not the same as low kV or computer grade carpet)

For more information on conductive flooring solutions for electronic industry end user environments, read these articles, part of the Staticworx Knowledge Center:

• Static Control in a 9-1-1 Call Center: City of Lowell Case History
• Static Control Flooring for Data Centers (featured in The Data Center Journal)

How to Ground SD Monolithic Seamless Epoxy Coating Floor

Client Question
We are considering applying Staticworx Groundworx ESD epoxy paint over two surfaces in our building. The areas are either sealed concrete or covered with regular VCT. Will the Groundworx floor meet ESD standards even though it will be installed on top of non-ESD flooring? - Keith, Texas

Answer
My company's Staticworx Groundworx Epoxy is produced using graphite particles. These particles create a conductive matrix within the liquid. When applied over any surface, insulative or otherwise, the Groundworx cures into a homogeneous ground plane in all directions. Continuity is achieved across all points of Groundworx regardless of the electrical properties of the surface underneath it.

However, the “Groundworx ground plane” still needs to be grounded once every 1000 square feet using our copper ground strips. The strips are 2 inches by 24 inches in length. They can be attached to the floor using glue or double-sided tape. Part of the strip touches the floor and the other end of the strip should attach to an electrical box, a piece of conduit, building steel or a metal stud that is in continuity with the AC or building ground. (See article: Best Way to Ground ESD or Static Dissipative Flooring) When applying the Groundworx, make sure you coat over the portion of the copper strip touching the floor. This is the only necessary step for grounding a Groundworx floor.

Learn more about Staticworx Groundworx Epoxy
Read this article on the Staticworx website, in the Knowledge Center Area

Polyurethane is an insulator and a static generator

QUESTION:We are considering installing ESD tile in our facility. We have heard that tiles with polyurethane coatings (PU) might be easier to keep clean. Is this true? Can you recommend a floor that requires low maintenance?
Josh, Androgon Networks

 

ANSWER:
Polyurethane (PU) coatings are used by luxury vinyl tile (LVT) manufacturers. A coating of PU helps reduce the use of waxes and sealers on flooring installed in retail spaces, hospital corridors, shopping malls etc. Unfortunately PU is a non-conductive coating so defeats the purpose of the conductivity of the tile. That’s why they shouldn’t be used on floors that are intended for low static generating applications. This coating would insulate access to the conductive, carbon matrix sealing it inside the PU, keeping the tile from eliminating static effectively.  (See the Staticworx illustration on how conductive tile works > )

 

 

The PU coating would increase the electrical resistance of the tile leaving the floor unable to meet ANSI/ESD S20.20-2007 ESD standards. PU is an extreme static antagonist making it a major static generator; a floor coated with PU would allow for the accumulation of high static charges on people when they walk on the floor with any shoes.

 

If you think maintenance will be a major problem in your facility, you should at least consider a precision milled ESD tile with high vinyl content. These tiles are commonly called solid vinyl tile (SVT.)  The surface of SVT can be buffed and returned to its original appearance regardless of age, traffic or soiling. The properties run all the way through the thickness of an SVT tile so you never need to worry about abrasion affecting performance. The precision milling ensures a tight gap-free installation. Tight seams prevent that ugly dark line that often appears in between VCT tiles.

 

You may also want to explore EC rubber flooring. Unlike vinyl, rubber doesn’t have any pores that could trap dirt in the first place. And, conductive rubber is the only floor that will reduce static on people wearing standard street shoes. All other resilient ESD flooring requires the use of static protective footwear. EC Rubber is the most fault-tolerant ESD flooring available.

Fault-Tolerant Anti Static Flooring

Wikipedia defines “fault tolerant design” or “fail safe design” as “design that enables a system to continue operation, possibly at a reduced level…rather than failing completely”.¹

Over the years, I have found that this is a very successful way for customers to think about their ESD flooring needs. For most environments, the hazard of static to equipment and/or operations is a risk that cannot be taken. Fault-tolerant ESD flooring is intrinsically anti-static: the end user won’t need to do anything after it is installed except walk on it while it allows for the most user errors. Fault-tolerant ESD flooring allows for the most flexibility in an environment while keeping that environment safe:

• People can wear the wrong shoes but still remain protected
• Waxes, polishes, and sprays need not be applied or monitored
• Ambient humidity, temperature, traffic, and the age of the tile are taken out of the equation

In mission critical environments, like labs, call centers, healthcare and cleanrooms, there is no room for static or the human error that can bring static if high maintenance ESD flooring is used. Based on the application where the ESD flooring will be installed consider the following elements when evaluating the selection of anti-static flooring:

1. Footwear: Will the shoes worn in the environment be standard “street shoes” (insulative) or will they be specialty footwear (conductive)?
2. Volts (kv): What is the acceptable amount of human body charge allowable in the environment?
3. Static decay: Upon contact with the floor, how quickly does the charge leave the body?
4. OHMs: What is the floor’s measurable ability to conduct electricity?

(See image, below)

¹ “Fault-tolerant_design,” Wikipedia, http://en.wikipedia.org/wiki/Fault-tolerant_design, Dec. 1, 2009

Confusing Terminology

Have you been asked to select a floor that is supposed to eliminate or minimize static charges accumulating on people when they walk on the floor? What do you call such a floor? If you have done any research in this area you’ve probably discovered something rather unusual. There seems to be many different and seemingly contradictory descriptors for this type of floor. To make this point, here are just a few descriptors used by the construction industry to describe this floor (and a free resource to help you decode them).

 

Section 09 61 36 of The Construction Specifications Institute (www.csi.com) calls this kind of floor a  Static-Resistant Flooring Treatment. That makes sense; the purpose of the floor is to resist static. But wait; would it also make sense to control static? Control as in eliminate, mitigate, inhibit. There appears to be another CSI category (09660) called Static Control Flooring. What’s the difference between static control and static resistant? Before you answer that question here’s another CSI category: 09 65 33. This category is called Conductive Resilient Flooring. (Info courtesy of www.aecinfo.com) That’s three descriptions for what seems to be the same thing.

 

The construction Specification Institute isn’t the only source of confusion in this dilemma of identifying technically sound walking surfaces that can eliminate static on human beings. Try using the www.google.com search engine to find your solution. Start out with words that make logical sense in a search for something that should prevent static. Try the words “antistatic flooring.” The first thing you will notice is that Google will ask you, “did you mean anti static flooring?” So try searching anti static flooring instead of searching the way you originally spelled it. Now you get different search results than you did using the first spelling. Ditto if you hyphenate anti-static instead of spacing the two words. Now things really get really blurry. You’re looking for “something” that the construction industry can’t describe consistently and the worlds of Google, Bing and Yahoo can’t seem to spell right. And worst of all, you are only looking at antistatic. You haven’t even searched other descriptive synonyms like conductive, static dissipative, grounded, static-free, ESD safe, ESD flooring, shock resistant, static mitigating or non-static and low static generating. Some Internet searches even resort to application-oriented strategies in the hopes that they can whittle down the possible options based on suitability. They’ll plug in words like like: data center flooring, hospital operating room flooring, cleanroom tile, MRI suite flooring or flooring for handling explosives.

You could have a field day thinking up all the possible word combinations for this kind of walking surface. Several years ago we actually created an Excel spread sheet that contained over 2000 possible word combinations for something that is supposed to do the following:

· Permanently prevent static on people who are standing or moving

· Be certifiable to some standard that verifies safety and performance

· Meet the requirements of the space, environment and application

 

I hear questions and comments about this dilemma ever day. This confusion is the number one reason we get calls from end users asking us to test their static flooring solution because something doesn’t seem to be right. Recently, we were asked to test some anti static high pressure laminate (AKA HPL) installed on raised access flooring panels in a semiconductor fabrication facility. The client believed their maintenance department must have harmed the HPL floor because the floor was no longer antistatic. And as a result, extremely low levels of static — lower voltage discharges were zapping static sensitive parts than can be felt by a person. It turned out that the HPL floor was never a good investment because it was incapable of discharging static on people walking on it. The floor lacked the most basic ingredients required to transport electricity from one place to another; it was not made with electrical conducting materials like carbon, graphite, silver or gold. Without the presence of electrical conducting materials, it is not possible for electricity to move through a material. Instead, electricity was getting stuck. The static charges were staying on the people and on the floor. We call that kind of electricity – static electricity. If you don’t understand this concept think of an electrical plug. There’s a reason you don’t get a shock when you plug your hair dryer into an AC electrical outlet. It’s because the plug is made of a non-conducting plastic material. If the plug were made with conductive materials electricity would flow through it. You would also get a shock.

 

So, how do you get on track and find this elusive floor that has no universal name, can’t be spelled properly and apparently if you don’t get lucky and describe it right, you could end up with the opposite of what you wanted?

 

Oh, and one more thing, once you get the description down you will need to decide if the floor should be resilient, carpet, paint, wax, rubber, vinyl, epoxy, urethane, HPL, or maybe matting. Could this be confusing? We think so. That’s why we built www.staticworx.com. Every single article, specification, test result and comment has been vetted by independent standard organizations or technical editorial boards. And, if that is not enough, we update and refute any technical premises that have been superseded or proven to be incorrect.

Lunch and Learn FAQs: Static Conductive Flooring vs. Static Dissipative Flooring

Our presentation team has identified three basic, frequently asked questions during recent lunch and learn seminars with architects:

1.       What is the difference between static dissipative and conductive flooring?

2.       How does an ESD floor route static charge to ground?

3.       Is ESD rubber flooring more expensive than vinyl?

What is the difference between static dissipative and static conductive flooring?

Experts unanimously recommend conductive flooring over static dissipative flooring, especially whenever static discharge might compromise or corrupt a mission critical operation or manufacturing facility.

Static Dissipative (SD) flooring requires changing the chemistry of the flooring compound through the use of chemical additives. Static dissipative floors are defined by a property called electrical resistance, which is measured in ohms. The important parameter for describing a floor is the static control flooring resistance to ground or path to ground. In order to meet the qualification of static dissipative, a floor must have an electrical resistance to ground of ≥ 1 X 10⁶ (one million ohms) AND < 1 X 10⁹. Static dissipative should never be confused with the terms Conductive or Antistatic (sometimes hyphenated as anti-static).

1. Static dissipative properties are not permanent and cannot be bought with a lifetime warranty. They migrate out of the flooring material after extended use. After several years, static dissipative flooring loses its static dissipative properties.

2. Static dissipative flooring will not meet all the requirements of static control performance standards. For example, static dissipative rubber cannot meet the ESD requirements of ANSI/ESD S-20.20 for system resistance.

3. Static dissipative flooring does not reduce static quickly enough to meet the needs of Class 0 or explosives and munitions handling.

Static conductive flooring attracts and routes static electric charges away from valuable electronic equipment. Inherently conductive carbon is added to the flooring compound when it is manufactured, creating electrically conductive pathways within the flooring.

1. Static conductive properties are permanent and are bought with a lifetime warranty.

2. Static conductive flooring will meet all the requirements of static control performance standards, ANSI/ESD S-20.20.

3. Static conductive flooring does reduce static quickly enough to meet the needs of Class 0 or explosives and munitions handling.

 

How does an ESD floor route the static charge to ground?

Pathways in the flooring drain the charge through, into conductive adhesive, and on into copper stripping where the charge dissipates to ground.

 Is ESD rubber flooring more expensive than vinyl?

ESD Vinyl is about 60% of the cost of ESD rubber. Installation, labor, freight, etc. would be the same for either floor.
Rubber has a lower cost of ownership.

Anti Static Flooring Lunch and Learn for Architects

To schedule a lunch and learn presentation with one of our ESD flooring technical directors, contact us at info@staticworx.com or call 617-923-2000.

Computer Grade 3.5 kV Carpet and ESD Carpet Are Not the Same

Recently, our technical director was contacted by a general contractor looking for a way to take standard carpet tile and make it conductive. During the conversation, it quickly became apparent that this GC had fallen victim to a mistake based on misunderstanding terminology. He had installed low kV carpet tile--not static control carpet. He was caught in a tough situation because his client was expecting ESD, grounded, conductive carpet tile installed on top of a new access floor. The GC wanted to know if he could improve the static dissipative performance of the carpet tile if he removed it and reinstalled it using conductive flooring adhesive.

What’s the difference between Low kV and ESD, conductive carpet? (See graphic, below)

Low kV carpet cannot be grounded because it is not made with conductive materials.  It is made with anti static additives. These additives are temporary and their performance is diminished by foot traffic and general abuse. Low kV carpet will not reduce static electricity when the relative humidity is low and all anti static properties disappear after several months of wear and maintenance.

Low kV carpet will not generate as much static electricity as standard carpet. Low kV carpet reduces the shock hazards associated with walking on standard carpet. The typical human threshold for feeling a static zap is 3.5 kV, or three thousand five hundred (3500) volts. Most low kV carpet will inhibit static sufficiently so that people do not feel painful shocks. However, these marginal static control carpets do not guarantee safety for electronic equipment, which can be affected by discharges as low as 100 volts--far below the discharge level perceptible by humans. Additionally, the static control properties on low kV carpet decay overtime.

ESD, conductive carpet is comprised of conductive fibers which are capable of safely conducting electricity to a ground source, such as an electrical conduit. Most conductive fibers contain carbon, graphite or stainless steel. Conductivity is a permanent property--independent of humidity, maintenance or abuse.

Understanding electrical resistance and grounding
Understanding the relationships between electrical resistance, grounding and static control performance would have enabled the GC to avoid a costly error. With this basic knowledge, he would have realized that he was not buying a carpet tile with permanent electrical properties verifiable with a simple ohm meter, but rather an anti static coated product that temporarily prevents people from getting shocks.

In this scenario, the GC had misunderstood the AATCC 134 static generation test results printed on the back of the low kV carpet information sheet. He thought low kV static generation test results were the same thing as good electrical conductivity. Had he known to ask one key question, he would have saved his client significant aggravation: where does this product fall in the range of electrical resistance for ESD flooring systems?

As defined in ANSI/ESD S20.20-2007 for system resistance, there is an ideal range regarding electrical resistance for ESD flooring systems: see the graphic below. If the carpet is not electrically conductive, it is not possible to ground the carpet regardless of the type of adhesive used. In this case, the carpet was actually insulative – the opposite of electrically conductive. Therefore, static charges have no mechanism of dissipating through the carpet to ground no matter what adhesive is used.

Moral of the Story
Like a chain whose strength lies in links, conductive flooring is only as good as its weakest link. If any link in that chain is broken or inadequate, the system will not prevent static problems.

Low kV carpets have no conductivity – they are insulators. Insulators cannot be grounded, nor can they dissipate static charges. Static accumulations on any person walking on or any item rolling on an insulator cannot be prevented. Static can only be dissipated through a floor with conductive pathways. Therefore, an effective static control carpet tile must have conductive properties in the carpet tufts, the carpet backing, the adhesive and the ground connection.

Learn More

• The Difference Between Low kV Carpet and ESD, Conductive Carpet, in detail
• Installing Carpet Tile on Non-Access Floors
• Installing Carpet Tile on Access Floors
• Staticworx Carpet Tile Sustainability, Green Information

ESD Flooring 101: The Non-Technical Answer to Dissipative vs. Conductive

Question: I am an interior designer. We have been asked to specify a floor for sensitive electronic parts handling. What is the difference between static dissipative tile flooring and conductive flooring? I would greatly appreciate it if you could possibly avoid technical jargon in your answer.

Answer: This is the most commonly asked question. Since you have asked for a non-technical answer, I will try to use some familiar examples in my explanation.

Pretend for a moment that instead of controlling the flow of static electricity, you are trying to control the flow of water.

Let’s think about the way water flows through a funnel. To control the flow of water, a funnel collects the water in a storage area and redistributes it through a smaller diameter bottom.  By shrinking or increasing the diameter of the funnel orifice, we could either increase or restrict the amount of water that will “discharge” from the funnel. You could say that the exit of the funnel provides resistance to the flow of the water. The smaller diameter orifice slows down the water flow compared with just pouring the water out of a container.

If we were to compare the electrical concepts of “conductive” with “static dissipative” using a water flow analogy: a conductive floor would equate to allowing the funnel to restrict only 10% of the water flow while static dissipative flooring  would equate to restricting over 90% of the flow.

Ninety-percent restriction is too much resistance. If the funnel is getting refilled periodically, it is likely that 90% restriction will not empty the funnel fast enough to keep up with the periodic refills. That is essentially what happens when a person walks on a high resistance static dissipative floor. Think of a charged person as the storage area of the funnel and think of the floor as the orifice of the funnel. The right floor should be able to drain static off the person at a sufficent rate to prevent the person from accumulating too much static. You could say that excessive static on the person would be the same as the top of the funnel over flowing.

If the floor – like the small diameter funnel – can not drain static as quickly as a person can generate static, the person will discharge static charges to electronic equipment instead of to the floor.

Understanding static dissipative epoxy vs. conductive epoxy?

Customer Question: We are considering the use of a static-free epoxy floor coating for our electronics manufacturing area. Should we install a conductive or a static dissipative epoxy floor? The epoxy contractor has told us that either version will meet ANSI/ESD S20.20.

Answer: There are numerous misconceptions and misapplications of ANSI/ESD S20.20. Very few flooring suppliers understand this document and as a result they make improper recommendations. Without a complete understanding of S20.20, the wrong product could be purchased and installed. Is the supplier stating that the floor meets the resistive properties referenced in 20.20 or that the floor will meet S20.20 as part of a system? These are two very different performance parameters and only the second reference matters.

Let’s start with the concept of “meeting S20.20.” ANSI/ESD S20.20 is a process document – not a specification. Flooring does not meet S20.20; it meets recommended parameters derived from standard test methods referenced in S20.20. For example, S20.20 references not one but 3 standard test methods:

1.   ANSI/ESD STM 7.1: Floor Materials--Resistive Characterization of Materials. Any flooring material must measure below 1.0 X 10E9 ohms to ground. However, the flooring must also comply with the 2 parameters listed below:
2. ANSI/ESD STM 97.1 Floor Materials and Footwear--Resistance in Combination with a Person. The recommended maximum system resistance is 3.5 X 10E7.
3. ANSI/ESD STM 97.2: Floor Materials and Footwear Voltage Measurement in Combination with a Person. The recommended maximum voltage allowed is 100 volts.

Many flooring manufacturers state that their floors will meet ANSI/ESD S20.20. What they actually mean is that their floors will always measure less than 1.0 X 10E9. That fact has nothing to do with using a floor in a program that must meet the 2007 revision of S 20.20 because the floor is one part of a bigger picture. The full picture involves the combination of the floor, people, ground connections and controlled footwear. Hence the need for standards 2 and 3 referenced above.

Needless to say, it would be very difficult for a flooring material measuring in the upper static dissipative range (> 5.0 X 10E7) to be part of a total system measuring less than 3.5 X 10E7. The math just doesn’t work. Adding a person and footwear will increase the total system resistance to ground. Furthermore, it has been demonstrated that most static “dissipative coatings” are incapable of keeping body voltages from exceeding 100 volts. Since the premise of ANSI/ESD S20.20 is preventing body voltages above 100 volts, it is impossible to state that a static dissipative floor measuring less than 1.0 X 10E9 will meet ANSI/ESD S20.20-2007.

A warranty stating compliance with ANSI/ESD S20.20 is not sufficient.  
A floor should never be evaluated in isolation. It must always be qualified as part of an overall system that includes all variables including the person and the controlled footwear. When the system is evaluated, the only way to confidently meet the recommended parameters of ANSI/ESD S 20.20-2007 is to install a floor measuring less than 10,000,000 ohms to ground. 

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Note: this page is also posted on our FAQs page.