Desco TB-5527 Service Manual

TB-5527 December 2008 Page 1 of 2

Wrist S trap s
Grounding, Testing and Maintenance

ESD Systems.com • 432 Northboro Road Central • Marlboro, MA 01752 • [phone] • Fax [phone] • Website: ESDSystems.com

Location of Proper
Ground Point

Wrist straps, work surfaces, and
floor mats which are to be
grounded for protection against
electrostatic discharge (ESD)
should be grounded to a common
point. The common point should be
connected to the “green wire”
equipment ground.

Figure 1. Common point ground for
each workstation

This may be accomplished in a
variety of ways utilizing common
point ground blocks, ground buses,
or connecting directly to the
nearest utility “green wire” ground
point. In a properly wired building,
the nearest reliable ground point
will be the center screw of the
standard 110VAC outlet.

Figure 2. “Green wire” equioment
ground

Each individual workstation must
be individually grounded to the
ground bus or “green wire”
equipment ground. Do not wire

work surfaces or other ESD
devices in series or “daisy
chain” them. This can create

unknown resistance and
unacceptable grounds.

Test The Ground Before
You Use It And Periodically
Thereafter

Do not assume that any AC
electrical outlet is properly wired.
Even if it was originally wired
correctly it can become
ungrounded due to corrosion and
wear. Test the ground you intend
to use before you hook up. SPI
Westek recommends that you use
the AC Outlet Analyzer & Wrist
Strap Tester Item 94380.

A Banana Jack Is
Recommended

Almost all wrist strap
manufacturers terminate wrist
ground cords with banana plugs.
This is because the banana plug
and jack have proven to be a fast
and reliable way to attach to
ground. If you must use another
method such as snaps or alligator
clips, due to your particular
environment, be sure to test the
connections often.

Note: Many wrist strap users clip the
wrist cord to the edge of an ESD
protective mat. This process is not
recommended as it can increase the
total system resistance to ground to
over the 35 megohm limit
recommended in ESD S 20.20. (ESD
Handbook TR20.20 section 5.3.2.2.2
Wrist Strap Ground Cord)

Compliance Verification of
the Ground System

Set up a schedule to be sure that all
ESD grounds are inspected and
tested periodically, every six months
for example.

TECHNICAL BULLETIN TB-5527

Made in America

© 2008 DESCO INDUSTRIES INC.

Employee Owned

BENCH MAT

WRIST STRAP
WITH COIL CORD

COMMON POINT
GROUND #09826

FLOOR MAT

FLOOR MAT
GROUND #09814

GREEN

WIRE

EQUIPMENT

GROUND

WARNING!

DO NOT

DAISY CHAIN

THE WRIST STRAP!

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 resistor), and
the interface with the wearer’s skin.

SPI Westek has several testers
available for this purpose. For
more information, see our web site
for tester models and detailed
technical bulletins.

If you obtain an open or bad reading
from the tester you should stop work
and test the wrist band and cord
individually to find out which item has
failed. Replace the bad component
and test the system again. Obtain a
“Pass” reading before beginning work.

Cleaning

For proper operation, the wrist
strap, especially the wrist band,
must be kept clean. All wrist band
should be cleaned with a mild
detergent on a periodic basis. Be
sure that metallic expansion wrist
bands are thoroughly dried to
prevent corrosion.

Woolite™ works well. Liquid
detergents are better than dry in that
there is less caking and frictional
wear. Launder elastic wrist band strips
in cool or warm water, tumble dry with
low heat or hang dry. This works well
if using a standard house machine on
gentle cycle. Industrial machines are
fine if "Pony" (typically under 200
pound loads) machines are used. It is
not recommended to launder .. in
heavy industrial laundry machines as
it will lead to premature wear. Should
be tumbled dry using low heat. DO
NOT BLEACH.

NO

Limited Warranty

SPI Westek expressly warrants that
for a period of one (1) year from the
date of purchase, SPI Westek Wrist
Straps will be free of defects in
material (parts) and workmanship
(labor). Within the warranty period,
the product will be tested, repaired,
or replaced at our option, free of
charge. Call our Customer Service
Department at 909-664-9986 for a
Return Material Authorization (RMA)
and proper shipping instructions and
address. Include a copy of your
original packing slip, invoice, or other
proof of purchase date. Any unit
under warranty should be shipped
prepaid to the SPI Westek factory.
Warranty repairs will take
approximately two weeks.

If your unit is out of warranty, call
Customer Service at 909-664-9986
for a Return Material Authorization
(RMA) and proper shipping
instructions and address. SPI
Westek will quote repair charges
necessary to bring your unit up to
factory standards.

Warranty Exclusions

THE FOREGOING EXPRESS
WARRANTY IS MADE IN LIEU OF
ALL OTHER PRODUCT
WARRANTIES, EXPRESSED AND
IMPLIED, INCLUDING
MERCHANTABILITY AND FITNESS
FOR A PARTICULAR PURPOSE
WHICH ARE SPECIFICALLY
DISCLAIMED. The express warranty
will not apply to defects or damage
due to accidents, neglect, misuse,
alterations, operator error, or failure
to properly maintain, clean or repair
products.

Limit of Liability

In no event will SPI Westek or any
seller be responsible or liable for any
injury, loss or damage, direct or
consequential, arising out of the use
of or the inability to use the product.
Before using, users shall determine
the suitability of the product for their
intended use, and users assume all
risk and liability whatsoever in
connection therewith.

TB-5527 Page 2 of 2

ESD Systems.com • 432 Northboro Road Central • Marlboro, MA 01752 • [phone] • Fax [phone] • Website: ESDSystems.com

© 2008 DESCO INDUSTRIES INC.

Employee Owned

Wrist Strap silver fibers are sensitive
to heat and should not be exposed to
laundering heat in excess of 120°F.
Use only non-ionic softeners and
detergents when laundering."

Size Adjustment of
Wristbands

Metal Expansion Wristbands

1. Insert the link end of the
wristband into the slotted opening
on the cap. Insert it at a downward
angle to allow the links to slide
inside the channel in the backplate.

2. Change the size of the band by
sliding the links in or out of the
stainless steel backplate. For extra
small users you can cut off excess
links with cutters.

3. Lock the links into place by
pulling down on the band, seating
the band securely over the lip on
the edge of the backplate.

4. Test the wrist strap system to
be sure of proper electrical
resistance and skin contact. Use
the procedure described under
“Testing” section on reverse side.

Note: SPI Westek’ wrist straps and
coil cords are UL Listed for safety.
However, this product is not recom­mended for use on equipment with
operating voltage exceeding 250 VAC.

CAUTION: The ESD Series is for
electrostatic control. It will not reduce
or increase your risk of receiving
electric shock when using or working
on electrical equipment. Follow the
same precautions you would use
without wrist straps, including:

• Make certain that equipment having
a grounding type plug is properly
grounded.

• Make certain that you are not in
contact with grounded objects other
than through the ESD Series.