ESD Wrist Strap Testing – What Does High Fail Vs. Low Fail Mean?

October 12, 2021

PGT120: Wall Mounted

The wrist strap is the most common and effective method for removing voltage from operators working with static sensitive devices. Unfortunately, over time, soil build up or mechanical issues can cause a wrist strap to fail.  Therefore, wrist straps must be tested regularly with an ESD Test Station to assure that people are not transferring voltage sensitive devices and causing ESD damage.

Many common ESD Testers have a both a High Limit and a Low Limit for wrist straps:

High Limit

Industry standards (ANSI/ESD S20.20) requires a wrist strap to have a resistance of less than 35 megohms. Anything above that, and you will receive a “high fail” alarm from the ESD tester. When the resistance of a wrist strap is too high, excess voltage may build up on the body and could cause an ESD event. The high fail can be can be caused by:

  1. High skin resistance (have the operator use an electronics approved lotion).
  2. Soiled or poorly fitted wrist band (check that the band is snug and not overly worn).
  3. Broken coil cord.  It is possible that the wire inside the cord has been damaged.

Lower Limit

Most wrist strap testers also test for low resistance (typical low fail is less than 750K ohms) , to assure that the 1 megohm resistor is present and performing as intended.  The purpose of the 1 megohm resistor is for safety: to limit the amount of current that could be transferred through the body. The 1 megohm resistor is designed to limit the current to 250 microamps at 250 Volts rms AC, which is below the perception level of humans. A “low fail” result can be caused by

  1. The person is connected to ground via another path, i.e., touching a grounded metal structure.
  2. The most common cause of a fail low is a shorted resistor in the wrist strap coil cord. Replace the coil cord with a new one and repeat the test.

If an ESD Wrist Strap fails high, it means the wrist strap’s resistance is too high and is not removing voltage efficiently. If it fails low, the wrist strap may have an issue with the 1 meg resistor, which is a safety concern. Either way, the wrist strap or coil cord should be replace to ensure you are protected from damaging ESD.


ESD Product Category: Personal Grounding

April 16, 2021

In a world full of static, you need to protect your sensitive electronics from being destroyed. Transforming Technologies offers an extensive selection of static control products, such as ionizers, matting and more to keep your products safe. But what about your personnel?  Grounding your workers is an essential function of an ESD Program.  These products are grouped into a category called Personal Grounding.  View all of our personal grounding products on our website. Contact 419-841-9552 for more information!

ESD Product Category: Anti-Static Ionizers

January 16, 2021

Various Applications for Ionization

Ionizers deliver a balanced stream of positive and negative ions and are used primarily to control static charges on insulating materials such as standard plastic. Transforming Technologies carries a wide variety of ionization products for use in industries such as electronics assembly, cleanroom, semiconductor, flat panel display, medical device manufacturing and pharmaceutical.  Ionizers are the ideal solution to dust and contamination, process lockup, spray painting, static shocks, quality control, and much more.

View all of our anti-static ionizers on our website.

Contact 419-841-9552 for more information!


How To Properly Sanitize ESD Table Mats?

June 25, 2020

How To Properly Sanitize ESD Table Mats?With the Covid-19 virus on everyone’s mind, companies are asking how to properly clean and sanitize ESD rubber table mats in a way that will not affect their static control performance.

So for the past several weeks, we tested two common cleaning agents known to control the Covid-19 virus; Isopropyl Alcohol (IPA) and Lysol.  The is concern is that repeated use of IPA or Lysol will degrade the ESD performance of rubber mat material, leaving sensitive components at risk.  We found that after 36 applications,  the ESD performance of table mats were not affected by disaffecting with IPA or Lysol.   For our testing, samples of our most popular rubber table mat, the MT4500 series, were sprayed twice daily, allowing the cleaning agent to stand for five minutes prior to wiping per the manufacturer’s instructions.   The mats resistance properties were tested daily, and after 16 working days of applications, the mats showed no change in their physical or ESD control properties. In some cases, the surface resistance readings improved. We suggest that users of our 2 layer ESD mats use an EPA approved cleaning agent to help prevent the spread of the Covid 19 virus but to perform regular compliance verification testing for any long term affects on the material.

For testing questions, download our guide on how to properly test ESD mats, or call us at 419-841-9552 or schedule a 15 minute meeting with a  static control expert to learn more.


How To Choose a Surface Resistance Meters

May 22, 2020

A Surface Resistance Meter is an instrument that measures electrical resistance of an object. It is an important tool in manufacturing, as well as static control and ESD prevention programs because it can be used to evaluate materials and classify them as conductive, dissipative and insulative.  Surface resistance meters are also commonly used to test the effectiveness of ESD control products such as auditing an ESD worksurface.

A quick internet search reveals many types with a wide range of capabilities and accessories. It can be difficult to choose which meter is right for your application.

Use our guide below to help with your decision.  The following are topics we will cover in this article:
  1. Accuracy

  2. Test Range

  3. Results Display

  4. Voltage

  5. Temperature and Humidity

  6. Electrodes

  7. Memory

  8. Summary 


1 . Accuracy:  Verification vs Qualification

Not all resistance meters are created equal.  Meters may be designed for quick measurements to confirm specifications (verification) while some meters are designed for more rigorous testing that requires more accurate measurements (qualification). How accurate your meter needs to be will depend on the type of testing you will be doing. Choosing a meter with higher accuracy will be a more expensive investment,  it will ensure quality measurements no matter what testing required. Below is a table that show a variety of meters with a range of functions. “Travel” meters are excellent for quick measurements and are very portable. Lab Grade meters


Entry Level “Travel” Meter


Mid Level “Travel” Meter

Metriso B530

Entry Level “Lab Grade” Meter

Metriso 3000

High Level “Lab Grade” Meter

2. Test Range

The minimum test range required for ESD purposes is 10^3 ~ 10^12 which covers conductive, dissipative and insulative items.  Entry level meters will only have this range and will display “Less Than 10^3” for low resistance and” Greater Than 10^12” for high resistance items. More accurate resistance meters will have a larger test range.  The  Metriso 3000 has a test range from 1 Ohm ~ 1.2Tera Ohm  (1.2 x 1012 ohm).  The larger test range is important depending the material being tested.

3. Result Display: How will your meter display the measurement?

Results are measured in Ohms and are sometimes displayed in powers of 10 (also known as the decade scale). The simplest readouts show values with LED lights coded with the decade scale with colors to signify conductive, dissipative, and insulative.  This readout is less accurate because the actual measurements may fall in between a decade and is rounded to the closest number. More accurate meters will display the values digitally, either in the decade scale or in Ohms. 4. Voltage: Choose The Right Voltage for Your Application Surface resistance meters use voltage to test the resistance of a material. The voltage required depends on the material you are testing and the test method. Generally for ESD testing, conductive materials (1.0 x 104 ohms to <1.0 x 106 ohm) are tested at 10v and materials in the dissipative range (≥1.0 x 106 ohm to <1.0 x 109 ohms or < 1 x 1011 ohms for packaging materials) are tested at 100v. (Learn when to use 10v and 100v). Most meters will be able to test at both 10v and 100v. They may switch between the two automatically based on the material or you may have to select the voltage manually. The verification of insulative materials may call for a higher voltage, such as 500v.  There are specially designed meters for that voltage such as the Metriso 3000. Another concept to understand with resistance meter voltage is “constant voltage”. A meter that has constant voltage does not drop significantly from the selected voltage during testing. For example, when 100 volts is selected, the meter will deliver 96 and 100 volts at the probes (standard requires ±5%). Some meters, referred to as “Open Circuit”, will drop the voltage to a much lower level when the resistance of the material measured is less to protect the meter from the returning current.  A meter with constant voltage is a much more accurate tool. The Metriso 3000 is a constant voltage meter and the output voltage at the probes is displayed during testing.

5. Temperature and Humidity

The humidity and temperature affect the electrical properties of the material being tested. It is possible for a material to meet the requirements at high humidity, but fail at a lower humidity. Because of this, both the ESD Association and the European CECC recognize the environmental effects on test measurements and require them to be recorded. Some resistance meters may have the capability to test temperature and humidity built in while some do not, and external devices may be required.  When in doubt, it is best to get a meter that measures temp & humidity.  If your meter does not have that capability, we supply a tool that precisely measures temperature and humidity.

6. Measuring Electrodes

All surface resistance meters contact the material to be tested with components called electrodes. Electrodes can be built into a meter (called parallel electrodes) or can be external components.  The electrodes you require with your meter depends on the tests you will perform. Parallel Electrodes:  Two conductive rails are built into the back of the meter and are used to give fast electrical resistance measurements.  Not all meters have parallel electrodes. External Electrodes:  A variety of external electrodes can be connected to a surface resistance meter depending on the type of test.  Here is a list of some external probes:

7. Memory

Some meters record measurements in internal memory, making reporting very convenient. Recording measurements is a nice feature, but may not be necessary for everyone. Our Metriso 3000 can store 50,000 data points and includes software to create reports. Some mid- level resistance meters can also store data, such as the Metriso SRM200.  The amount of data points required during your testing sessions will help you determine if you need internal memory.

8. Summary

The surface resistance meter you should choose will primarily depend on the type of test required. Do you require very accurate measurements to qualification testing or just simple measurements for verification? Will you taking large amounts of tests regularly? Or just periodically?  For simple testing needs, a entry level “travel” meter such as the SRM110 will be all that is required.   For higher level testing, a mid-level Travel Meter such as the SRM200  with probe accessories or a Lab Grade Testing Kit like the Metriso B530 or 3000 should be considered.

If you have any questions on Surface Resistance Meters, please contact Transforming Technologies at 419-841-9552 or email You can also fill our a Form on the Website or Chat with the link on the right.


About Cut Resistant Gloves

April 1, 2019

GL2500 StaticCare ESD Cut Resistant Gloves

Cut Resistance Gloves

Cuts and lacerations are responsible for nearly 30% of lost-time work injuries in North America, the majority of which are to the hands. Wearing the correct glove is the most critical factor in proper hand protection. It’s even more important to understand cut resistant gloves and the characteristics they hold. Cut-resistant gloves come in various fabrics offering different level of cut resistance. It’s important to consider the requirements of a particular application when choosing a glove material.  Transforming Technologies specializes in anti-static gloves which improves the quality of products or solves a process issue.

What Are Cut-Resistant Gloves?

Cut Resistant Gloves can be divided into three categories based on the materials they are made from: metal mesh gloves, cut-and-sewn, and seamless knitted gloves.

Metal mesh gloves are a form of chainmail and are made of rings of stainless steel.

Cut-and-sewn gloves can be made using only a cut-resistant material or by using conventional materials with full or palm lining of cut-resistant materials. The materials are cut to shape and sewn into a glove.

Seamless knitted gloves are knitted in one piece and the cut protection is provided by high performance materials such as Para aramid (Twaron, Kevlar), Ultra High Molecular Weight Polyethylene (UHMWPE), special PVA yarns (SupraBlock) or steelfibre and fibreglass yarns. The gloves are usually coated with solid or foamed Latex, Nitrile or Polyurethane.

Which Cut Resistant Glove Is Right For Me?

Not all cut-resistant gloves are created equal and that’s a good thing, depending on the severity of the hazards that you’re facing. The best rated glove is the one that protects against the hazards you face. A worker who uses a box cutter once a day doesn’t need the same protection as someone who works in metal stamping eight hours a day.

Using a glove designed for heavy-duty cut protection for a light-duty application has a snowballing effect: If a worker has less dexterity in the glove, they won’t be able to do their job right. If they can’t do their job right, they won’t wear the glove and then compliance takes a hit. Then the risk of hand injury skyrockets!

How Are Cut-Resistant Gloves Rated:

There are two common standards used for measuring the cut-resistant properties of gloves. One used primarily in North America and the other is used in Europe and Asia.

North American Standard (ANSI/ISEA 105-2016):  The protection level is given by a number between 1 and 9, where 9 indicates the highest cut protection.All gloves are tested on a TDM1000 machine which provides uniform testing.

Transforming Technologies supplies a Cut Level 2 ESD Gloves.

  1. The glove sample is placed on a conductive strip and loaded onto the TDM-100. When the metal blade touches the metal strip, the test is terminated.
  2. A straight blade is loaded into the machine.
  3. Weight is added to serve as force.
  4. The blade moves across the fabric.
  5. The blade is replaced with a new one to ensure accuracy.
  6. The sample is cut five times, each with three different loads.
  7. The distance traveled to cause cut through at various forces is recorded.
  8. The data is used to determine the load required to cut through the sample.
  9. The glove receives a rating based on the above information between A1 and A9, with A1 being the lowest and A9 being the highest level of cut protection.

European Standard (EN 388): The protection level is given by a number between 1 and 5, where 5 indicates the highest cut protection. Until 2016, the Coup Test, as described below, was the only test used under the EN 388 standard. The standard update in 2016 introduced the ISO 13997 concept, which closely relates to the North American standard test.

  1. A test sample is taken from the palm of a glove.
  2. A rotating circular blade moves back and forth across the test sample until a cut-through is achieved.
  3. The test sample is compared to a reference material (usually cloth).
  4. The reference material and the test sample are cut alternately until at least five results are achieved.
  5. To help account for a loss is sharpness to the blade, the reference material is cut before and after the test sample.
  6. The cut resistance is a ratio of the number of cycles needed to cut through the test sample compared with the reference material.

Can You Wash Cut-Resistant Gloves?

The short answer is yes. Laundering and dry cleaning have no significant impact on the protective properties of cut-resistant gloves. Most quality cut-resistant gloves will retain their protective properties even after ten or more washes. It is important that you follow manufacturer instructions when washing cut-resistant gloves.

Frequently Asked Questions:

Q. Do cut-resistant gloves offer good puncture-resistance?

A. No. Many cut resistant gloves are manufactured to protect hands from being slashed by sharp objects like knives/blades. However, they may provide very little or no puncture resistance from a pointed item, such as a needle.

Q. What is the difference between puncture resistance and needle or needlestick resistance?

A. Needles are sharp, beveled cutting instruments designed to pierce the skin. To stop them you need to stop the cutting action by putting something hard in front of them, such as the protective guard plates found in SuperFabric® brand materials. ASTM/EN388 test probes are rounded and tear fabric instead of cutting as it penetrates. This rounded ASTM/EN388 tip functions more to test bust strength whereas the .25G medical needle tests true needle resistance. Various testing bodies throughout the world have acknowledged this deficiency and are adapting standards to meet this. Two examples are the Canadian research organization IRRST and the ASTM F23 Standards committee, who are working together to design a standard that uses the same test procedures as tested herein.

Q. Should cut-resistant gloves be used to protect one from cuts from powered/mechanical equipment like powered saws and drills?

A. Most all manufacturers of cut-resistant gloves will not suggest the use of cut-resistant gloves for protection against powered devices. Gloves are typically tested for use with non-powered blades and sharps only.

The use of a glove with powered equipment could potentially harm an individual. If the moving blade catches the glove, it could result in a person getting pulled into moving machinery. Moving machine parts have the potential for causing severe workplace injuries, such as crushed fingers or hands, amputations, burns, or blindness. Safeguards are essential for protecting workers from these needless and preventable injuries. Any machine part, function, or process that may cause injury must be safeguarded, especially when the operation of a machine or accidental contact with it can injure the operator or others in the vicinity. These hazards must be either eliminated or controlled.

Q. What makes HexArmor products highly cut and puncture resistant?

A. HexArmor® products offer industry leading cut protection through the innovative configuration of SuperFabric® technology which provide resistance to lacerations and slashes like no other material on the market. Typical cut-resistant products are made of high performance yarns such as Kevlar®, Dyneema®, or Spectra®. While blends of these technologies protect users from straight edged cut hazards, they do not offer sufficient protection from variable hazards such as metal burrs, wires, or slivers.


How To Choose an ESD Jacket

January 8, 2019

ESD jackets, also commonly known as ESD smocks, ESD lab coats or ESD garments, offer protection from electrostatic fields generated by clothing on the user’s body.  ESD jackets are worn where ever static damage is a concern.  ESD jackets differ from common work garments because they are made with a grid of conductive fibers throughout. The grid creates a “Faraday Cage” effect around the body of the operator that shields charges generated from the operators clothing from damaging ESD sensitive devices. The conductive fibers also lowers the static charge generation of the jacket(also refereed as tribocharging) to a safe level.

ESD Jackets as part of a complete Quality Control Program.

ESD jackets are the most visible sign of ESD protection and any facility that mandates ESD garments demonstrates a commitment ESD protection. ESD jackets are a recommended addition to a program that already includes typical grounding measures, such as wrist straps and heel grounders.  This is because of the potential hazard of the operator’s clothing.  The ESD TR20.20-2008 states: “While a person may be grounded using a wrist strap or other grounding methods, that does not mean that insulative clothing fabrics can dissipate a charge to that person’s skin and then to ground. Personnel clothing usually is electrically separate or isolated from the body.”

How To Choose an ESD Jacket?

A quick search online reveals numerous options for ESD jackets. We have summarized the main considerations when choosing ESD jackets:

ESD Garments come in many shapes and sizes.  Typical distinctions are:

  • Fabric Composition
  • ESD Properties
  • Collar Options
  • Sleeve Terminations
  • Length
  • Color 
  • Embroidery

The jackets you choose will most likely depend on style preference but the ESD properties should be the first priority to ensure the jackets will protect against ESD as intended.

ESD Properties
There are three classifications of ESD jackets per ANSI / ESD S20.20: an ESD Garment is defined as either:

  • Level 1: Static Control Garment (surface resistivity of < 1 x 10^11 ohms resistance);
  • Level 2: Groundable Static Control Garment (surface resistivity of < 1 x 10^9 ohms resistance); or
  • Level 3: Groundable Static Control Garment System (surface resistivity of < 3.5 x 10^7 ohms resistance).

ESD jackets are classified by ESD properties (how conductive they are), with level 1 being the lowest and level 3 is highest. Level 1 jackets are typically the lowest cost but because the ESD properties are low they may wear out faster and need to be replaced more often. Level 3 jackets are conductive enough that the fabric can be used as part of the ground path for wrist straps which allows for safe, hands-free grounding. Level 2 is in the middle.

How to Test ESD Properties

There are several ways to test an ESD jacket but for general purposes, a sleeve-to-sleeve measurement is the most important.  This test is used to confirm electrical continuity across garment panels and sleeve components.  At minimum, an ESD jacket must be dissipative (surface resistivity of < 1 x 10^11 ohms resistance).  This test is performed with a Surface Resistance Meter.  The ESD properties should be included in the data sheet for the ESD jacket from the manufacturer. It is always recommended to regularly test your ESD jackets because wear and tear and laundering will effect the ESD properties over time.

Testing an ESD Jacket with a Surface Resistance Meter

Fabric Composition

Fabrics composition will vary by the manufacture but are typically made with a combination of carbon with polyester fabric or a cotton polyester blend.  Commonly, the fabrics are described with a percentage. For example, 88% polyester and 12% carbon.  Your choice of fabric will be determined by operator comfort and ESD performance.  You may choose a lightweight polyester for warmer climates or a cotton polyester blend for cooler climates. 

The amount of carbon in the jacket is important to note because this is the element that makes the jacket “ESD safe”.  The more carbon, the better the anti-static performance.  Lower cost ESD jackets are available with a carbon content of less than 5%, but they may not perform well or last as long as jackets with higher carbon content.

Collar Options
Collar options typically include Lapel, V-Neck or Military style.  The type of collar you choose will be based on user comfort and sensitivity of the application.  The various collars allow more or less clothing to be exposed to your environment. V-Neck collars are the most open and may be cooler to wear. Military Collars covers the most clothing, but may more uncomfortable to wear.  Lapel collars are in between the two and are the most commonly used collar.

Sleeve Terminations
ESD jackets have either a Snap Cuff or an ESD Knit Cuff. The snap cuff includes three snap that adjusts for a proper fit and are typically cheaper. The three snap cuff is ideal when you already have wrist-straps, or in cases when wearers find the cuffs a little too snug. A wrist strap can be snapped to the garment sleeve and cord is attached at the hip pocket to ground both the person and the jacket.

An ESD Knit Cuff is very similar to the cuff on the end of a sweatshirt and allows for hands free grounding. ESD Knit cuffs form a contact path around both of the wearer’s wrists. The garment and wearer can then both be grounded by attaching a ground cord to the 4mm stainless steel snaps on the hip pocket.

Short sleeve jackets are also available from some manufacturers.

ESD jackets come in three lengths: waist length, 3/4ths and full length.  The length you choose depends on the sensitivity of the application and the comfort of the wearer.  Waist length jackets leaves the most clothing exposed but may be cooler. Full length jackets cover the most clothing by going down to about the knees and are sometimes referred to as lab coats.  3/4ths length jackets come down to mid-thigh and are between the waist length and full length.

ESD Jackets come in many colors, with blue the most common. The color has nothing to do with performance and is only preference by the company using them. Many companies will color code their employees with their ESD jackets. For example, employees may wear blue, management wears black and visitors wear white.  High-Visibility jackets are available for safety reasons. Color options vary by manufacturer, and by fabric. Jackets may also be died to match company colors but will have a high minimum order quantity.  

Embroidery of ESD jackets

Many companies choose to embroidery their company logo or employee name onto their ESD jackets.  Sublimations, screen printing and patches are also ways to add logos or names.


ESD Jackets are an important part of an ESD program. There are many styles to choose from, but ESD properties should be the most important factor in choosing an ESD jacket. After you ensure your jacket will protect your application, you have your choice of fabrics, collars, sleeves, and colors.

View Transforming Technologies’ line of ESD Jackets.

Need help choosing an ESD jacket? Call Transforming Technologies at 419-841-9552. Or email or fill out our contact form below.


How To Remove Static Electricity From The Conveyor Belt

July 3, 2018

The conveyor belt is an indispensable part of the automatic transportation equipment. But the conveyor belt can be a major generator static electricity that can cause numerous problems, from static shocks to employees to catastrophic damage to components. The cause of static is friction, and on belt conveyors, the belt surface is continually rubbing the pulley surface, generating static electricity. As the conveyor continues to operate, the static charge will continue to accumulate and increase unless it is bled off (or discharged) in some manner.  Conveyor and assembly trays can also create a static charge and shock employees.

Anti-static conveyor equipment exists, so when choosing the conveyor belt, pay special attention to whether the belt has anti-static characteristics.  A surface resistance meter can be used to measure the anti-static properties of a conveyor belt. But if your equipment is not anti-static, then you must eliminate static in other ways.  The first step in eliminating static is to measure it.  If you can feel the static charge or receive shocks, then the charge is already way to high and needs to be addressed.  Human feel static at 2000 volts, but components can be damaged with as little as 100 volts.  A static field meter can be used to measure the static charge on your conveyor.

Drag chains can be a do-it-yourself solution to drain a charge, but they are not always practical or effective enough.  Anti-static ionizers are the most effective method of eliminating static on conveyors. Ionizers blow specialized air that eliminates static charges.  They are designed to be mounted overhead, or in targeted areas and can be effective without interfering with the movement of the conveyor or components. Ion bars are excellent for conveyors because they can cover wide areas with a relatively small footprint. A three fan overhead ionizer is also an effective ionizer for conveyors. If the target area for ionization is small, ionizing nozzles can be very effective.  They provide a targeted stream of ionized air that can even be activated automatically with a photoelectric eye.

This will vary by application.  Mount ionizers at friction points in your process and the locations of the biggest static issue. Mount the ionizer as close to the problem area as possible, but not too close that the ionizer does not have enough time to do its job.  If your employees are getting shocked, you will want to install the ionizer just prior to the employee exposure.


Conveyors generate static due to friction, which can cause numerous problems. Anti-static ionizers are a very effective tool to remove the static charge.

View all of Transforming Technologies Anti-Static ESD Ionizers here.

There are THREE types of Static Control Garments that are compliant to the ANSI/ESD S20.20-2014 Standards.

Steve Cooter of United Static Control Products explains the Levels on their website. Below is an excerpt:

1) Static Control Garment – Level 1

These smocks are primarily designed to shield the technician’s clothing from the ESD Sensitive product. They DO NOT come with a ground snap and DO NOT require a ground cord. When these static control garments come into contact with the users skin (the user’s skin is about as electrically conductive as the garment) the static charge is equalized and goes to ground via the technician’s primary ground source (normally an ESD wrist strap and or ESD heel grounders).

2) Groundable Static Control Garment – Level 2

These smocks are primarily designed to shield the technician’s clothing from the ESD Sensitive product but they also provide redundant protection in the unusual event the smock does not make contact with the users skin. The ESD smock has a snap on the hip that can connect a  ground cord to create a path to electrical ground. A Groundable Static Control Garment is NOT recommended as the technician’s primary ground source (an ESD wrist strap and or ESD heel straps are still required).

3) Groundable Static Control Garment System – Level 3

These smocks are designed to act as a primary ground source for the technician (they can act as a replacement for a wrist strap). In addition to grounding the technician, they will also help to shield the technician’s clothing from the ESD sensitive product. They are reliant on good skin to smock contact. Hence, they may come with ESD cuffs or snap style cuffs that fit snugly around the users wrist.

United Static Control Products has been writing about ESD control since 1995 and their website has over 400 pages of information.  Their line of ESD jackets can be viewed here.


Follow this link to learn more about Transforming Technologies line of ESD jackets.


A Wireless Wrist Strap For Grounding and ESD Control – Does It Work?

May 6, 2016

The Wireless Wrist Strap – Do They Work?

 We Put Them to the Test!  And They FAIL!

The wireless wrist strap has been available for over 10 years.  We have seen them used in the electronics manufacturing and other assembly applications and have received several inquiries about their performance. In this blog, we test and report on the effectiveness of the wireless wrist strap. Our results indicate wireless wrist straps fail to ground operators or keep operators sufficiently neutral. Read why the wireless wrist strap system results in a potential nightmare of problems and view the hard data that proves they don’t work.

wireless wrists strap

Background: The Wireless Wrist Strap Dream It would be nice to be able to effectively drain the charge from a person without them tethered to a work station with standard wrist straps or other ground connection.  ESD flooring and footwear is an option, however it can require a significant investment for it to be effective. Hence, the dream of the wireless wrist strap. So what about the wireless wrist strap?  The advertising says “This compact wrist strap eliminates static without the need for a pesky grounding cord.  This allows you freedom of movement so you can leave your work area without needing to unclamp yourself and lose your anti-static protection.”  It also states that the band “…ensures that you have a much smaller static build-up and dissipates it quickly.Wireless Wrist Straps vs. Physics That all sounds wonderful in theory, unfortunately it does not work as advertised.   Most companies follow the ANSI/ESD S20.20 standards for their ESD Control Programs which requires human body voltage to be less than 100 volts and the wireless wrist strap does not meet the requirements of the standard. The standard states “All personnel shall be bonded or electrically connected to the grounding/equipotential bonding system when handling ESDS items.” The standard goes on to list the requirement of a resistance between the operator and ground of less than 35 megohms.  This requirement seems quite impossible to meet with the wireless wrist strap. Corded wrist straps Resistance to Ground of person wearing a corded wrist strap wireless-wrist-strap-walking-test Resistance to Ground of person wearing wireless wrist strap But what if you are not tied to the industry standard and just want to make sure that you are not generating excessive voltage that could harm electronic devices or assemblies?  The voltage generated and stored on the person is what is important.  So let us conduct another measurement that compares the voltage generated on a person that is a: not grounded, b: grounded through a conventional wrist strap/cord system and c: a person wearing the wireless wrist strap. The Walking Test For this test we will use the Warmbier WT5000 walking test instrument.   This instrument measures and records the voltage on a person while walking or simply standing.  To measure the voltage we held the test electrode on the instrument and repeated the six step walking test described in ANSI/ESD STM97.2 – Voltage Measurement in Combination with a Person.
Figure Standard shoes, tile floor, with no wrist strap

Figure 1: Standard shoes, tile floor, with no wrist strap

You see that from Figure 1 that the voltage on the person wearing standard shoes on a tile floor and no wrist strap was greater than -500 volts.   This voltage is well in excess of the damage thresholds for many devices today.    Next we will try the same floor and footwear but the operator will wear a standard wrist strap with coil cord (Figure 2).
Standard shoes, tile floor, wearing corded wrist strap

Figure 2: Standard shoes, tile floor, wearing corded wrist strap

In this case you should notice that the voltage is minimal.   The peak voltage was -1.41 volts and the valley was +0.46 volts. Finally, we test the same floor and footwear with the wireless wrist strap (Figure 3).
Cordless wrist strap

Figure 3: Wireless wrist strap

The graph in Figure 3 shows that while wearing the wireless wrist strap, voltages of greater than -100 volts were reached within one second of the test and peak voltages exceeding -500v were reached in less than 10 seconds. Wireless Wrist Straps are Unacceptable So in addition to not being electrically bonded to ground, the wireless wrist strap does not prevent charge build-up or decay charge at a rate that is acceptable for handling electronic devices. It would be nice to be able to handle electronic devices without that bothersome coil cord getting in the way or without having to invest in a flooring and footwear system, however the reality is that a person must be physically and electrically attached to ground to drain charge from their body.