[TowerTalk] Grounding, redux

[Peter Dougherty]

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.

Questions:
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.



Cheers,

Peter,
W2IRT