[TowerTalk] [RFI] Back of desk grounding buss

[Jim Lux]

On 3/21/14 6:28 AM, n8de at thepoint.net wrote:
> I've been following this thread for a while and wonder why no one has
> mentioned that a 'ground bar' is NOT a single-point ground.
>
> Think of the 'ground bar' as a series-string of very low value RESISTORS.
>
> Now ... think of your equipment as being connected to the 'nodes'
> between each of those resistors ... rig A at one end, then rig B at the
> first 'node' ... rig C at the second 'node' ... etc.
>
> During a lightning strike, the huge voltage of the strike MIGHT appear
> across that 'string' of resistors, causing each 'rig' to be at a
> DIFFERENT potential.
>
> POOF !!
>
> I suggest that each piece of equipment have its own 'ground wire' and
> those all be connected to a SINGLE point, perhaps at a point closest to
> the ground rod.  (Mine are all connected to a #0 wire going through the
> wall to the ground rod about 7' from the 'single point'.
>
> G



One hopes that the current is not flowing along your grounding bar.  The 
big reason for a bar along the back is that it's easy to connect wires 
to it, rather than having a rats nest of longer wires all going to some 
common point.

I doubt that in a typical "bench" or "table" scenario, that there is any 
real difference in chassis potential between a "bus bar with short 
stubs" and "radial grounding to a single point".

The big thing is to make sure that they're all bonded together, and that 
that bonding is to something relevant to where the transient is coming 
from.