[Elecraft] K3 ESD

[Fred Jensen]

On 12/18/2010 3:58 PM, Don Wilhelm wrote:
> Fred,
>
> Your statement of connecting to an equipotential plane is a good one,
> but your concern about spikes and inductive reactance back to the
> "planet" should not be a concern. It IS important that all items in the
> protected area be connected to the SAME point on this safety ground.
> Connecting one ESD prevention device to one green-wire ground, and
> connecting yet another device to yet another receptacle's green wire
> ground will cause a difference in potential between those two points on
> the green-wire ground.

I think that's sort of what I was trying [poorly] to get at ... one 
ground point, if you can't do that, don't ground.

EVERYONE:  Listen to Don, he's more precise.
>
> The same principles apply to installations like commercial broadcast
> stations which must remain in operation throughout a lightning storm.
> The solution is to keep everything in the station at the same potential
> through the use of a "grounding window" - which is the single point to
> which *everything* in the station is connected. In the event of a
> strike, it does not matter whether that grounding point raises to
> several thousand volts - everything connected to that point will also
> rise in potential by that same amount.

As a Starving Student at Cal Poly in the late 50's/early 60's, I worked 
at the local TV station on the engineering crew to support myself.  Our 
TX and main studio were co-located next to the 500 ft tower on Cuesta 
Ridge.  We had a single-point ground that involved a lot of copper, and 
we took a lot of lightning hits, mainly on the tower but strangely, 
sometimes to the ground and a few times to the building [concrete 
block].  Maybe it was finding the rebar?  At any rate, all the 
inter-rack and console cabling ran in trenches in the concrete floor 
covered by 3/8" steel trench covers.  For reasons well above my pay 
grade, a lightning hit to the tower would cause a deafening, 
bone-breaking "clang" from the trench covers, until we bonded them 
together along the edges with grounding braid.

73,

Fred K6DGW
- Northern California Contest Club
- CU in the 2011 Cal QSO Party 1-2 Oct 2011
- www.cqp.org