[Elecraft] (OT) Grounding Mat

[David Woolley (E.L)]

Gary Hvizdak wrote:
> Wed Mar 24 22:14:20 EDT 2010 LS (W5QD) wrote ...
> 
> The mat doesn't have to be grounded ...
> 
> 
> WARNING!  The statement W5QD just posted is completely false!  The ESD mat
> must be grounded in order for it to be able to dissipate an electrical

The full reply from W5QD was perfectly correct. Everything conductive 
has to be connected together, but there is no need to connect to the 
earth itself.  In practice, if the soldering station is mains powered, 
the result will be that it is also connected to the green wire in the 
mains, although that can be at a significantly different potential than 
the local true earth.  In fact, unless there is a high resistance in the 
lead to the mat, it can be very dangerous to connect it to true earth, 
as it is usually possible to touch the connection to the mat and 
something cannected to the green wire, at the same time.


> charge.  If you don't ground the mat, then you might as well not have it,
> since your entire work area could very easily be floating at tens of
> thousands of volts above ground, just waiting for "somewhere" to discharge
> "to" and "something" to discharge "through"!

That is perfectly acceptable, as long as there is no way of touching 
something that has a relatively low resistance to true earth. 
(Incidentally, I have a feeling that true earth isn't actually 
electrically neutral, something has to balance the charge in thunderclouds.

In a practical amateur environment, the optimum ground for this purpose 
is the green wire, and bringing any other ground into the situation can 
be dangerous.  However, if you have a battery or gas soldering iron, and 
no conductors which could touch the work, but aren't connected to the 
mat, there need be no connection at all to anything approximating true 
earth.

The green wire is not a best approximation to true earth for this 
purpose, it is actually the ideal thing to connect to, even if it bears 
no resemblance to true earth.

-- 
David Woolley
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