[ale] Should I ground a ethernet switch?

[Mike Harrison]

> Indeed DO use the ground rod as Jim suggests (make it as long as possible) 
> but don't use simple wire for lightning protection.  You should instead use 
> copper strap (http://www.dxengineering.com/parts/dxe-cs2-25 plus the ground

The strap, with a large flatish surface, is used because lightning level 
strikes travel on/near the surface of such straps. I've seen it described 
as 'plasma', but more importantly, I've seen it with my own eyes. It's 
impressive.

Now a lesson in grounding: At the normaal residential level, you want a 
SINGLE point of ground, typically tied to the ground/nuetral buss at the breaker 
panel. Beware of having two (or more) physically separate grounding 
points, there can and often is a small voltage difference between them.
Small, but the kind of things that can cause noise in audio gear.

IF you are a ham radio operator, your tower and radio shack might have 
it's own ground, and while commonly not done, it should be isolated from 
the your house. Isolation transformers are used.

If you are a wireless ISP (I was), my tower and all of the associated 
electronics (Motorola Canopy gear, GPS Clock.. etc.. ) was isolated with 
it's own big flat grounding strap and ground field (collection of copper 
rods in ground, meshed together), a proper isolation transformer that did 
not pass 'ground' and a fiber optic ethernet connection. A configuration 
which later owners of the business did not understand and it cost them 
replacemment gear several times...

Measured with a standard Fluke volt meter, the ground on the gear
was often several volts (AC) different from the main building ground,
but this place pulled some serious juice and lots of things bled to 
ground. And more than once I've seen a ground wire to a plumbing pipe..
that itself was isolated by some PVC adapter or fitting.

=======================================================
Now the big question:

   WHY is there a grounding tab on that ethernet switch?
=======================================================

It has a metal case, but an isolated "wall wart" style power supply. The 
grounding lug is therefor required by law because the metal case (an 
excellent heat sink and very sturdy industrial case) might shock you if 
there is current leakage from the electronics. Any device with a 
conductive case is supposed to be grounded, to bleed off the leakage from 
inductance, capacitance and just plain broken parts/wiring.
It -MIGHT- help you in a lightning or other strike if it were grounded,
or it might just be a good path to ground if there was nothing else
and blow everything attached to it. It's purpose is your safety.

Personally, I've never grounded them....

Signed: a former biomedical engineer, who used to have to worry about 
ground loops and static electricity as a source of ignition for flammable 
(explosive) anesthetics.., and sources for issues (15 uA can 
cause fibrilation) with people with electrodes on or in them..