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Re: [TowerTalk] Grounding, redux

To: Peter Dougherty <>,
Subject: Re: [TowerTalk] Grounding, redux
From: WD0M <>
Date: Fri, 11 May 2007 15:42:34 -0600
List-post: <>
If I may address one point - I'd never invite 
lightning inside the house - put your 
Polyphaser/ICE devices outside on a SPG 
to  preclude allowing Thor's hammer inside the 
house where it may do even more damage.  I have 
them at the SPG at the tower base, as well as in 
a NEMA box on the outside of the house.  I'm with 
you - over engineering is better than being 
sorry.  I live in a lightning center of 
Colorado....severe thunderstorms happen in this 
part of the mountains in Colorado.  Can't be too 
careful.  I've had one hit on the tower and everything worked as planned.



At 03:30 PM 5/11/2007, Peter Dougherty wrote:
>Hi all,
>Getting ready to put my ground system in shortly but will be shopping
>for Polyphasers, etc at Hamvention next week.
>Here's what I have. One 70' crank-up tower about 5 feet from the back
>wall of my house. I've driven in a bunch of ground rods ~16 apart
>(most are down all 8', some only 5 feet due to rocky soil, however)
>going around my house on 3 sides. The fourth side is a paved
>driveway, so that's not happening any time soon. It will eventually
>connect to the service panel once I can get an electrician to come by
>and hook it up, per NJ code.
>I also have a bunch of Cadweld one-shots for AWG-4, but I haven't
>purchased the wire yet. I'm guessing AWG #4 solid is the right choice
>for this application? Given copper prices, 2-gauge is too expensive.
>1) How far below ground should I run these wires? I'm just using
>hand-tools to trench, not a ditch-witch, so the plan was about 3 or 4 inches.
>2) Polyphasers. This is a big question mark. Most things I've read
>say to mount 'em all on a single-point panel inside the house,
>strapped with a 2" or 3" copper bus to a ground rod outside the
>house, which in turn is connected to the ground rod system. I 've
>seen lots of pics online of polyphasers outside, in a NEMA box on
>a  tower leg, others saying I should have them physically connected
>to the tower and the top and bottom, AND inside the house on the SPGP
>panel, etc.
>3) TVSS (transient voltage surge suppressors): Yes? No? Maybe??
>Guys, am I over-thinking this or over-engineering this project for a
>70; crankup?? I've got 3 trees higher than that on the property, as
>do most of my neighbours, 250kV transmission lines at the end of the
>street and a 20 year history of never taking a direct hit at this
>house (100' tower by the previous owner with one ground rod and 4 GA
>round green wire). the only lightning hit that did anything came in
>on the power line as a surge that cooked my motherboard on the radio
>PC, despite an APC UPS.
>I'll be at the lightning panel in Dayton next week (probably asking a
>lot of questions afterwards, too), but can always use more guidance.


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