TECHNICAL BULLETIN TB-2005 Wrist Straps Made in the Grounding, Testing and Maintenance United States of America Wrist Straps per ANSI/ESD S20.20 Test The Ground Before You Use It And Periodically All personnel shall be bonded or electrically connected to Thereafter the grounding / equipotential bonding system when handling Do not assume that any AC electrical outlet is properly ESDS ESD sensitive items. When personnel are seated wired. Even if it was originally wired correctly it can become at ESD protective workstations, they shall be connected to ungrounded due to corrosion and wear. Test the ground you the grounding/equipotential bonding system via a wrist strap intend to use before you hook up. We suggest using Descos system. ANSI/ESDS20.20-2007 sections 8.1 and 8.2 item 98132 AC Outlet Analyzer and Wrist Strap Tester. Location of Wrist Strap Ground Point A Banana Jack Is Recommended Wrist straps, ESD worksurfaces, and floor mats are to be Almost all wrist strap manufacturers terminate wrist ground grounded to remove electrostatic charges connected to a cords with banana plugs. This is because the banana plug common point ground. The common point ground should and jack have proven to be a fast and reliable way to attach be connected with one ground cord to the green wire to ground. If you must use another method such as snaps or equipment ground. alligator clips, due to your particular environment, be sure to BENCH MAT test the connections often. COMMON POINT Note: Many wrist strap users clip the wrist cord to the edge GROUND 09826 of an ESD mat. This process is not recommended as it can WRIST STRAP WITH COIL CORD increase the total system resistance to ground to over the 35 megohm required limit of ANSI/ESD S20.20. Wrist strap ground cords must be connected to a groundable point or an FLOOR MAT equipotential bonding point. Do not connect to a snap on a GROUND 09814 dissipative mat unless it is the groundable point for the mat. Do not clip a wrist strap to the edge of a dissipative mat. ESD Handbook TR20.20 section 5.3.2.7 Best industry FLOOR MAT practice is that ESD Ground Connections should be firm Figure 1. Common point ground for each workstation fitting connecting devices such as metallic crimps, snaps and banana plugs shall be connected to designated ground This may be accomplished in a variety of ways utilizing a points. Use of alligator clips is not recommended. common point ground block, a ground bus, or connecting directly to the nearest AC green wire equipment ground 09835/09836 point. In a properly wired building, the nearest reliable equipment ground point will be ground or the center screw of the standard 110 VAC electrical outlet. Each ESD workstation must be individually grounded to the ground bus or green wire equipment ground. Do not wire worksurfaces or other ESD devices in series or daisychain 09740 them. This can create unknown higher resistance to ground. For a more detailed discussion of ESD grounding see Desco technical bulletin TB-2007. For instructions on grounding Desco worksurface mats see technical bulletin TB-2000. Figure 3. Descos 09740 / 09741 dual bench mount and 09835 / 09836 quad common point ground cord are two easy WARNING ways to provide multiple banana jacks at any workstation. DO NOT DAISY CHAIN GREEN Compliance Verification of the Ground System THE WRIST STRAP WIRE EQUIPMENT Set up a schedule to be sure that all ESD grounds are GROUND inspected and tested periodically, every six months for example. NO Testing the Wrist Strap The best test of the wrist strap system is while it is worn. This includes all three components: the wrist band, the ground cord (including current limiting resistor), and the interface Figure 2. Green wire equipment ground with the wearers skin. DESCO WEST - 3651 Walnut Avenue, Chino, CA 91710 (909) 627-8178 DESCO EAST - One Colgate Way, Canton, MA 02021-1407 (781) 821-8370 Website: Desco.com 2014 DESCO INDUSTRIES, INC. TB-2005 Page 1 of 3 March 2014 Employee OwnedWoolite works well. Liquid detergents are better than dry in Wrist straps should be tested periodically. The frequency of that there is less caking and frictional wear. Launder elastic testing, however, is driven by the amount of risk exposure wrist band strips in cool or warm water, tumble dry with low that can occur between tests. For example, what is the heat or hang dry. DO NOT BLEACH. quantity of product handled between test periods Wrist Strap silver fibers are sensitive to heat and should not Because wrist straps have a finite life, it is important to be exposed to laundering heat in excess of 120F. Use only develop a test frequency that will guarantee integrity of the non-ionic softeners and detergents when laundering. system. Typical test programs recommend that wrist straps that are used daily should be tested daily. However, if the Size Adjustment of Wristbands products that are being produced are of such value that knowledge of a continuous, reliable ground is needed, and Elastic Adjustable Wristbands then continuous monitoring should be considered or even required. Data taken from the test program will ultimately The elastic adjustable band is designed to be adjusted to allow the user to make the choice of how often the wrist the proper size to fit each individual wearer. After adjustment strap should be checked and which wrist straps have the it can be used as a fixed size band. It is only necessary to most useful service life. ESD Handbook ESD TR20.20-2008 adjust the size once. Wrist Strap section 5.3.2.4.4 Test Frequency 1. Place the wristband on the wrist. 19250 2. Open the clasp by pulling upward on the tail of material that extends out from the clasp. 19350 19246 3. Tighten or loosen the elastic material through the clasp Figure 4. Wrist strap testers until the wristband fits snugly but comfortably. Desco has several wrist strap testers available for this purpose. For more information ask for specification technical drawings or technical bullitens by item number. If you obtain a high or low reading from the tester you should stop work and test the wristband and coil cord individually to find out which item has failed. ESD lotion can be applied to the wrist 4. We recommend that you close the clasp and wear the area to improve the users interface with the wearers skin. band with the excess tail extended for a day to be sure Replace the bad component and test the system again. the adjustment is snug, comfortable, and has the proper Obtain a Pass reading before beginning work. electrical contact with the skin before cutting. 5. Test the wrist strap system to be sure of proper electrical Per ANSI/ESD S20.20-2007 section 7.3 Compliance resistance and skin contact. Use the procedure described verification records shall be established and maintained to under testing. provide evidence of conformity to the technical requirements. 6. When you are ready to cut off excess material, mark with The test equipment selected shall be capable of making the a pencil where excess material is to be trimmed. measurements defined in the Compliance Verification Plan. 7. Remove band from wrist. Open clasp. Cut off excess Cleaning material about 1/4 short of pencil mark so that the end of material is concealed by the cap. This will eliminate the For proper operation, the wrist strap, especially the wristband possiblity of exposed frayed ends. strip, must be kept clean. All wristbands should be cleaned 8. Close clasp and use as a fixed elastic wristband. with a mild detergent on a periodic basis. Be sure that metallic expansion wrist bands are thoroughly dried to prevent corrosion. DESCO WEST - 3651 Walnut Avenue, Chino, CA 91710 (909) 627-8178 DESCO EAST - One Colgate Way, Canton, MA 02021-1407 (781) 821-8370 Website: Desco.com 2014 DESCO INDUSTRIES, INC. TB-2005 Page 2 of 3 Employee Owned