Thank you, Jack... (see below) 
 
On Mon, 28 Feb 2005 00:38:18 -0500, "Jack Painter"  
wrote: 
 
Hi Buck, 
 
SNIP 
 
For HF-only feedlines (where an extra 40-60' of coax would add superficial 
loss) there should be no excuse for not bringing all feedlines into the 
structure only at the service entrance.  UHF systems that suffer much higher 
line loss tempt us to bring antenna feedlines directly into the radio shack. 
THAT causes a major bonding headache. This is because we have to achieve 
such low impedance connections to the service ground that lightning will 
never choose a path up from ground, through our equipment, and out via the 
house wiring to get back to the service entrance ground.  We are never fully 
protected from such occurrence if the station ground and service ground are 
apart from each other, no matter how well they are bonded.  But we can be 
reasonably protected in that respect, when the bonding jumper is of 
significantly lower impedance than the AC wiring in the home. 
 
#8 copper is no where near the "significantly lower impedance" we're talking 
about.  Either wide copper strapping or #2 or #4 copper would be a better 
example for the bonding connection between service entrance and station 
ground. The more places along the way that bonding jumper is also bonded to 
the outdoor antenna ground fields, radials, etc, the better.   Voltage 
division plays a big part when everything is bonded and many grounding 
electrodes are used. 
 
Hope this helps, 
73, 
Jack Painter 
Virginia Beach, Virginia 
 
While I am still digesting this a bit, I at least understand why I was 
so confused about the ground loop in the first place.  This also 
explains why some contradict each other. 
 
As for trying to reach the service entrance here, it is almost not 
practical to do so with the antenna elements.  The Service entrance 
here is kitty-cornered from both the shack and the direction of the 
antennas.  The antennas would have an extra 150 + feet to feed to go 
directly to the service entrance.  (dipoles only, no verticals at this 
time). 
 
The more I re-read what you said, the more I think I understand.  I am 
in the process of planning a move so I am not planning to improve 
conditions here but at least I know how to plan for the new QTH. 
 
My battery charger is double fused (positive and negative leads) so I 
would assume that if lightning tried to find its way to the ground 
side, it would blow the fuses first.  Of course, if it takes 10,000 
volts to jump approximately one inch and lightning is typically 
hundreds or thousands of feet high.... little good the fuse would be 
in a direct hit. 
 
One of my plans for my next QTH will be to mount feed-through SO-239s 
on an metal plate and connect my lightning arresters and ground them 
before the antennas come into the shack.  Based on your message, I am 
thinking that a good connection from there to the service panel ground 
would be good too? 
 
Thanks again, 
 
 
-- 
73 for now 
Buck 
N4PGW 
		 
		
		
		
		
		
		
		
		
	
	 |