A troll giving potentially dangerous advice about a subject he
apparently knows nothing about.
I'm not a troll. That is seriously what I read a few years back. But
accepting that that may have been BS info I have decided to revise
that info and go with this latest info. Personally, I don't use a
wrist strap because as you can see from this article it isn't so
simple to just stick on a ten dollar Radioshack wrist strap and think
you are properly protected. I've never fried a component yet, and as I
said before, any computer store I've been into where I've seen them
working on people's PC's they are not wearing wrist straps. Not saying
they shouldn't be, but they usually don't.
http://www.esdnw.org/Newsletters/05-08-02 Newsletter/Page 4.htm
The All Important Wrist Strap
By Bill Metz
Given that a worker can generate potentials of 5,000 volts (50
times higher than the level considered safe for modem electronic
components) by simply walking across the floor, a comprehensive
program to control ESD is an absolute requirement for manufacturing
quality electronic products.
The problem for most managers and engineers is determining which
ESD control products are appropriate for their particular application.
The first place to start is at the individual workstation. The best
way to remove the threat of ESD at the workstation is to discharge
conductors using grounded wrist straps, table mats and floor mats. But
it is important to prevent isolation at any point in the workstation
grounding system. One way to ensure this is by completing all
grounding to the safety ground in the facility grounding system, not
earth ground.
The general consensus is that the first element in any ESD control
program is personnel grounding. The most familiar tool, and one that
is often mistaken as sufficient protection from ESD by itself, is the
common wrist strap. Wrist straps come with a variety of bands ranging
from conductive plastic and bead chain to Velcro and conductive fiber.
The strap itself is usually comprised of multi-strand wire, but also
comes in solid conductive plastic and nylon. Most wrist straps include
a one megohm series resistor to limit current through the body in the
event of accidental contact with 120 volts AC.
The biggest problem with wrist straps is intermittent or permanent
discontinuity. Daily or more frequent testing of wrist straps is
extremely important to any ESD control program. This is why it is
recommended that wrist strap checkers be used to test for continuity,
and that the checkers be fitted with an alarm or have LED's that light
up when an open circuit or high resistance condition occurs. Many
discontinuities can be attributed to improper connection of the wrist
strap. Most experts warn that wrist straps should never be connected
through the work surface as a path to ground. Common work surfaces add
too much resistance for effective personnel grounding. The best
solution, say experts, is to use a separate, hard wired path to a
connecting socket or bus for the strap connection.
Another often-overlooked cause of discontinuity is the connection
to the wrist. The outer layer of the wrist often has a dead skin layer
that acts as an open circuit, particularly in dry climates. Body hair
can also act as an insulator. One way to avoid this problem is to use
ESD lotion. ESD or IC lotions are wetting solutions that are solely
designed to improve the electrical contact between the wrist strap and
the wearer. ESD lotions should never be used as hand cream. They lack
the key ingredients that are needed to make them a good hand cream.
Even though there are many other equally important elements in a
good ESD prevention program, the wrist strap can certainly be looked
upon as the first line of defense.
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