Shag Floor danger?

How dangerous is it from a grounding standpoint to do work inside a
computer while standing on a shag floor? I currently work out of my
home, and the only room in the house with sufficent lighting to do work
inside a PC has a shag floor. I have taken every other precaution to
avoid ESD -- I put the PC on a desk on an anti-static mat, I touch the
chassis before starting, I wear a wrist strap, I even strip to the waist
to avoid possible ESD from my clothes. Yet, I have had two systems now
unexpectedly go totally dead on me, and I'm wondering if it could
possibly be because I'm standing on a shag rug where I work?

Dave

Dave Hardenbrook

"Dave Hardenbrook" <> wrote in message
news: k.net...
> How dangerous is it from a grounding standpoint to do work inside a
> computer while standing on a shag floor? I currently work out of my
> home, and the only room in the house with sufficent lighting to do work
> inside a PC has a shag floor. I have taken every other precaution to
> avoid ESD -- I put the PC on a desk on an anti-static mat, I touch the
> chassis before starting, I wear a wrist strap, I even strip to the waist
> to avoid possible ESD from my clothes. Yet, I have had two systems now
> unexpectedly go totally dead on me, and I'm wondering if it could
> possibly be because I'm standing on a shag rug where I work?
>
> Dave

Shag, as in shag carpet? That's shagalicious, baby!

Seriously, you need humidity. Check ebay for a sling psychrometer, measure
the humidity, and get a humidifier. With the right amount of humidity your
static problems will go away.

-John O

John O

John O wrote:
> "Dave Hardenbrook" <> wrote in message
> news: k.net...
>> How dangerous is it from a grounding standpoint to do work inside a
>> computer while standing on a shag floor? I currently work out of my
>> home, and the only room in the house with sufficent lighting to do work
>> inside a PC has a shag floor. I have taken every other precaution to
>> avoid ESD -- I put the PC on a desk on an anti-static mat, I touch the
>> chassis before starting, I wear a wrist strap, I even strip to the waist
>> to avoid possible ESD from my clothes. Yet, I have had two systems now
>> unexpectedly go totally dead on me, and I'm wondering if it could
>> possibly be because I'm standing on a shag rug where I work?
>>
>> Dave
>
> Shag, as in shag carpet? That's shagalicious, baby!
>
> Seriously, you need humidity. Check ebay for a sling psychrometer, measure
> the humidity, and get a humidifier. With the right amount of humidity your
> static problems will go away.
>
> -John O

Another trick is a mix of fabric softener (like Downy) and water
in a spray bottle. In the dry months when humidity is low,
mist the carpet around the work area. Also, motion causes
static to build up. Once you've grounded yourself don't move
around any more than you have to, and especially don't sit on
a chair and rub your feet on the carpet. Don't walk around
with sensitive components (mobos, memory sticks, drives, etc.)
unless they're in Faraday cage (metalized/shielded) bags or
boxes. Test the integrity of the ground you're connecting
to. Make sure it's not open. Wear cotton clothes. Keep
plastics out of the work area. Cellophane tape and styrofoam
cups are especially static prone. An ionizer and static meter
can be helpful as well. It doesn't help to touch the chassis
if the mains (AC supply) cord has been unplugged. The key to
an anti-static mat is the star ground point. A ground (Earth)
reference is brought to the star ground point and everything
else is connected to that point. The wrist strap connects
there. A clip lead to the computer case connects there (so the
case is at ground without the mains cord). And any conductivity
the mat material provides flows to that point. That's the big
idea; everything at an equal potential (voltage) thus preventing
unexpected current flow through sensitive paths that can not
handle it.

And what does "totally dead" mean? What actually failed?
Static discharge damage isn't voodoo. It's possible to find out
whether static discharge was present or not. Static
discharge damage is often cumulative. Much of it happens
during manufacturing before the products are even in the field.
A good analogy is to arteriosclerosis (narrowing of arteries).
Static discharge damage can narrow conductive pathways without
completely opening them. If a pathway can still do its job
(pass enough current without opening up like a fuse), it appears
as though no static discharge damage ever took place. It's
only when the hard failures and intermittent problems occur
that any thought is given to static discharge damage. Then
it's assumed that a perfectly good device was zapped into its
present state by one recent occurrence. That's not necessarily
true. It can be that a previously narrowed pathway fails
because it was barely capable of conducting the necessary
current over a period of time. Mild surges, which aren't
necessarily abnormal over the course of typical operation,
can cause damaged pathways to open up without any recent
static exposure. What I'm trying to say is that over time
the odds of failure due to manufacturing and other handling
pile up. Your two failures may only have been coincidental
with your handling of the systems. And even with in depth
analysis you'll never know for sure whether it was your
handling, previous handling, or a combination that caused
the failures. And that assumes it is determined that static
discharge damage was the cause--which isn't always the case.
Devices fail for other reasons. And if you're really
concerned about the carpet (which I don't think you should
be), you can get or make a conductive floor mat and foot
straps for the work area. If you habitually rub your feet
on the floor or move around a lot when you work, that might
be worthwhile.

Always remember the golden rule: everything at an equal
potential. Earth ground isn't the only reference potential--
but it's common and handy in that static charges will
dissipate into it. Movement (motion) and objects brought
into the work area promote static, while humidity, ionization,
and the fabric softener/water blend work against it, and
a low resistance ground path dissipates/absorbs it.

I hope this helps.
--

Bill Eitner

Dave Hardenbrook wrote:
> How dangerous is it from a grounding standpoint to do work inside a
> computer while standing on a shag floor? I currently work out of my
> home, and the only room in the house with sufficent lighting to do work
> inside a PC has a shag floor. I have taken every other precaution to
> avoid ESD -- I put the PC on a desk on an anti-static mat, I touch the
> chassis before starting, I wear a wrist strap, I even strip to the waist
> to avoid possible ESD from my clothes. Yet, I have had two systems now
> unexpectedly go totally dead on me, and I'm wondering if it could
> possibly be because I'm standing on a shag rug where I work?
>
> Dave

I forgot to add a link:
http://en.wikipedia.org/wiki/Electrostatic_discharge
Good article and external links.

Bill Eitner