[TowerTalk] grounding compromises

Red RedHaines at centurytel.net
Sun Aug 6 18:14:22 EDT 2006

Hi, David;

Lightning protection is achieved by minimizing differences among all the 
conductors associated with the station (or computer or other equipment 
or person).

Start by minimizing ddifferences among the various grounded conductors, 
including AC power ground, telephone ground, cable service ground, water 
pipe ground, and all station grounds.

Ground the station equipment, every item associated with the station, on 
a single point or surface that is close to the station equipment.

Add surge suppressors or lightning arrestors to every power line, feed 
line, communication line, control line, and all other ungrounded 
conductors associated with the equipment, so that voltage on those lines 
is confined to a maximum difference with respect to the single point 
ground.  Mount those suppressors at the single point ground.  Mount 
additional suppressors at the feedline bulkhead and at each utility 

High voltage won't hurt you or your equipment unless you or your 
equipment complete the circuit from high voltage to low voltage (or high 
voltage of opposite polarity).  The bird perches safely on the high 
voltage line!  In the extreme case, with lightning, the path is 
completed through the air, via a corona or arc.  If all conductors are 
suppressed as specified, there will not be a voltage sufficient to arc 
from one of them to air.  Ground or suppress every conductor as 
described and stay indoors and you and your equipment will be as safe as 
possible.  Improving the grounding and reducing impedances will improve 
that safety.

73 de WOØW

David Talkington wrote:

>Hash: SHA1
>Salutations --
>I'm trying to arrive at the most appropriate grounding and lightning 
>protection solution for an 80m dipole at my small residence.
>The house electrical system ground is at the opposite end of the house 
>from the station.  To reach it from the bulkhead would require about a 
>50 foot run of either wire or strap, and would require three bends 
>around corners.  There is concrete around the perimeter for the entire 
>distance, and no crawl space or basement for that portion of the trip, 
>so a straight line isn't possible, and I can't put the entry point there 
>To avoid relying on this relatively high-impedance path to ground, I 
>have driven a copper-clad steel bar into the ground near the bulkhead, 
>and have a 10 foot, nearly straight line to it from the bulkhead.  The 
>coax will have a lightning suppressor inline at that point.  The entry 
>is into the basement, and runs up a couple of feet to the first floor 
>where the station is.  I will bond the water pipe (which is yet another 
>path to ground), heating ducts, and house electrical ground in that area 
>to the station ground.
>So ... there are now at least three paths to ground in the structure: 
>the electrical service ground, the copper water pipe, and my 
>supplemental electrode near the coax bulkhead.  This creates the 
>possibility of a potential or rise time difference between grounding 
>points.  Is this worth concern, or simply a necessary compromise in a 
>residential structure pressed into service as a radio station?  How have 
>others approached similar challenges?
>Cheers -d
>- --
>David Talkington
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