[Elecraft] Grounded or Not? (WAS:] Electrostatic ground)

[Ron D'Eau Claire]

Both Paul and Sandy pointed out that the real issue is the potential
difference between you, your tools and the ESD-sensitive components, so a
completely floating system in which everything on the work area is at the
same potential is perfectly safe for the components involved even if no
ground is present. 

That's true in theory, but I'm personally not comfortable counting on that
being the case. For example, my soldering station, along with all of my of
my AC powered test equipment, is grounded through the AC mains ground
system. So if I, my wrist strap and the components I'm working with are all
carrying an electrostatic charge and I pick up my soldering iron by its
insulated handle and touch it to a pin of the ESD-sensitive part, that
charge will be drained to ground through the iron and sensitive part. The
whole system is immediately defeated.  

My approach is to ensure that the outlet that serves my bench is truly
grounded to the AC mains ground and that everything on that bench is
connected in parallel to the same ground, including myself through a wrist
strap and a 1-megohm resistor. An anti-static pad is nice too. If used it
should be connected to the common ground through a 1 megohm resistor as
well. 

The important point about the work surface is to avoid those that collect
static charges easily. AVOID such bench coverings as rubber or a piece of
carpet!

While a wrist strap is a very good investment, its major benefit is to
protect you if you forget to ground yourself frequently by touching an
unpainted metal ground. Keep in mind that simply squirming around on your
chair can produce a destructive charge, so if you don't use a wrist strap,
have that ground within easy reach, remember to touch it regularly as you
work, use a grounded-tip soldering iron and you'll have no problems with ESD
damage.

Ron AC7AC

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Re: [Elecraft] Grounded or Not? (WAS:] Electrostatic ground)

[Brian Mury]

On Thu, 2006-02-16 at 13:51 -0800, Ron D'Eau Claire wrote:
 a completely floating system in which everything on the work area is at the
 same potential

 For example, my soldering station, along with all of my of
 my AC powered test equipment, is grounded through the AC mains ground
 system.

In that case you do not have a completely floating system. The tip of
your iron is not floating with the rest of the system.

 That's true in theory, but I'm personally not comfortable counting on that
 being the case.

The entire concept of ground is nothing but notation to make life
easier for us. There's no such thing as some point (ground) which has
zero voltage. Since voltage is a potential difference *between two
points*, it makes no sense to talk about the voltage of any single point
(including ground). When we talk about a point having a certain
voltage, what we are really saying is that it has a certain voltage
relative to an arbitrary point which we have labelled ground and will
use as a reference for all voltage measurements.

If it makes you feel more comfortable, designate your floating work area
as ground, and make sure everything has a small enough potential
relative to it - including your iron!
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