Question of the Day 02/03/06
Hello,
I am a manufacturing engineer
from Connecticut. We are setting up an assembly line where
ESD protection is needed for the components that will be
handled. Our line will have benches and various equipment.
There will be many people working in the cell and I am
concerned how to ensure that everything will be at the same
electrical potential. I am not familiar with ESD protection
so I am looking for help.
I reviewed the materials on
your website and I found them useful. It seems that an epoxy
floor system would best meet my needs. I saw the
illustration regarding bonding the floor to beam structure
for earth ground but I did not see how equipment would be
bonded to the floor. I will need to bond workbenches to the
floor. How is this done?
Do you strictly sell the
materials or do you also perform installations. I would be
interested in having someone install a floor system. Can you
recommend someone if this is something you do not do.
Regards,
Dan
Answers
Hi Dan,
Thanks for taking the
time to visit our site!
Your right on track
with using the
ElectraGuard ESD Epoxy flooring. The ElectraGuard can
indeed be grounded to a column (if convenient) however I
prefer to ground it to an AC electrical bldg ground as in
http://ultrastat2000.com/electraguard_grounding.html.
The ElectraGuard flooring has a bit of resistance built
into it for safety reasons (I.E. in case an errant electrician
happens to touch a hot wire;) so I wouldn't recommend
grounding your bench (s) and equipment directly to the
floor. I recommend that they too are attached to the
electrical ground system of the building. In the case
of the bench
this can be the center screw of AC electrical face plate
(fully compliant). The benches can be permanently
mounted to the ElectraGuard / Concrete substrate using
standard concrete fasteners.
The metal equipment framework typically get
it's ground from the ac electrical system (via the power
cord). In the case of non powered metal equipment (like
conveyors) attach a cable from the framework directly to AC
electrical ground. I like to test the resistance of the
metal framework of the equipment to AC electrical ground just to be
sure it is indeed grounding via power cable. FYI, the ESD
Association has shied away
from having us ground to copper ground rods that are not
attached to the ground system in the building (like I used
to do in the military). Independent ground rods can be at a
different potential very easily so it's bad juju;)
The potential or your
esd system will vary somewhat for safety
reasons and for controlling the discharge of static in a
timely manor. Sometimes discharging too quickly get's
you into more trouble than not discharging at all.
ANSI ESD S2020 recommends that the flooring system be in the
conductive range (resistance to ground <1.0E06. They will
let a static dissipative floor slide by for now (1.0E06 to
1.0E09). However conventional industry wisdom (as well
as the ESD Association are recommending (more and more) that the
range falls below 1.0E06. It will be mandatory in a year or
two (in my opinion).
Each operator is to
wear heel grounders (with 1 meg safety resistors).
They also recommend
that table tops or bench matting fall in the static
dissipative (>1.0E06, <1.0E09) range. If you are using
table top mats (and not esd laminated bench tops) and want
to ALWAYS be fully compliant, use a trilayer or dual layer
bench mat material (like our and
UltraComfort,
UltraTough or ElectraTherm
ESD rubber matting. The materials work great with
constant monitors too negating the need to test the
bench top material and wrist straps (saves a lot of
logging). I'd stay away from humidity dependant bench
matting (we clearly define the material's need for humidity
on our site's bench
mat menu). Humidity dependant materials are slightly
less money but not worth the headaches. Seems the humidity
(hence mat conductivity) drops drastically in esd audit
situations!
As you know along
with the operators wearing heel grounders they are usually
attached to ground with wrist straps (here again with each
strap having a 1 meg safety resistor built in). It's
important to have the GROUND for these wrist straps and the
mat (or bench laminate) all at the same potential.
Common point ground
blocks like our 113 AS makes this grounding requirement
fully compliant with the "grail."
Along with supplying
materials we often provide installation of the flooring,
equipment mats etc. Upon completion we provide
certification of flooring, benches, chairs and more all
tested to the latest industry
standards. Our ESD product certifications are typically good for a
year and really help keep the ISO boys happy.
Please let me know if
you have any further questions, never hesitate to email me
(or contact me on my cell) and thanks again for taking the
time to visit!
Ernie C.
At United
We take
static control seriously but make compliance easy!®
CONTACT
UNITED STATIC
CONTROL PRODUCTS!
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Colorado City, CO 81019
United States of America
Phone: 719 676
3928 Fax: 719 676 3929
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This page last updated on
08/23/2010
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