[TowerTalk] Grounding

[Shawn Donley]

I saw the one post on this topic about PolyPhaser saying grounds further apart than 75 feet "don't (effectively) see each other" during a lightning strike event even though they are bonded together.  I assume this is attributable to the propagation delay (LC time constants) between the distant points as compared to the lightning strike rise and fall waveform.


Brings up an interesting question for my own situation.   My tower is next to a detached garage.  The electrical inspector insisted that my tower, and it's grounding system of radials and rods plus a UFER, be bonded to the sub-panel in the garage for safety per NEC 810.  This sub-panel is bonded to the house service panel by the bare copper conductor in the underground feeder to the garage.


But it's 75 ft between the house and the garage, plus the house service panel is on the opposite side of the house.  So that's a run of about 150 ft between the tower and the house service panel, half if which is along the basement ceiling.


I wonder if bonding the tower to my home electrical system in this fashion is helping or hurting me if Thor decides to visit?


This fall I want to re-do my coax runs and change the entry point to the basement, mid-way between the opposite sides of the house.  I was thinking of running some #4 solid from the tower radial grounding system all the way around the house to the service entrance ground rod.  But this might make things worse by creating a loop that might magnetically couple with the stroke currents?


Sometimes it's really hard to get a good SPG for everything unless you're fortunate enough to be starting from scratch with a new house design..


OBTW... I control my rotor via Bluetooth.  Power for the rotor comes from the garage.


Before I put up my tower, I had one direct hit on a 40M  wire V-Beam fed with window line.  When I'm not operating I took that feeder off the entry panel and put it out in the middle of the yard with a brick on it.  Came home to find the antenna on the ground.  The window line was like a wet noodle.  No copper left in it....just plastic with cracks where the vaporized copper had departed.    The brick was laying at the bottom of a 1 foot hole in the yard.   Nothing in the house was affected.  But the cat was never quite the same after that when a storm came up.


N3AE