Saturday, March 12, 2005

Ground Map at AA6E

The figure shows the house plan at AA6E and how I am looking at the grounding problem. (Click for full scale view.)

Map of Proposed Grounding

The proposed stages of the grounding project, in order of increasing difficulty:

  1. Cross-connect ham radio "Single Point Ground" bulkhead to AC Service Ground at water pipe entrance using 1.5" or 3.0" copper strap.

  2. Develop a new buried ground system outside radio room. This would involve ground rods or cable buried in a trench in our shallow soil over rock ledge.

  3. Run a perimeter ground cable connecting the two lightning grounds, the AC service ground, and the ham SPG.
There is also an option 0, much inferior, which is to connect to the copper pipe hot water heating system that runs immediately adjacent to the SPG. This has a good DC connection, but obviously much higher inductance than other options.

One fairly strong argument for option 3 is that the tower is bonded to the lightning ground system (the bottom one), which could lead to problems if the ham SPG is not cross-connected.

6/16/2006 Note: Finally installed the 1.5-inch strap -- about 30 feet -- from the SPG panel to the waterpipe entrance ground (1-inch copper pipe). Before connecting the strap to the SPG, I measured a 3 mV AC differential. That's somewhat reassuring. "Soundings" in my lawn show that there is only 4 to 10 inches of soil above our rock ledge. That limits my ability to make a good new exterior grounding system.
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