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 ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
