[Elecraft] I need some grounding-strap guidance, if'n you please

[Jim Brown]

On Mon, 31 Aug 2009 21:14:50 -0500 (CDT), Rich wrote:

>Not only does that illustrate how a lousy ground can carry 
>quite a bit of current, but also why it is important to have 
>a good ground rod at your

WRONG!

The earth connection on power systems is a lightning discharge 
path, and it typically has a fairly high resistance to earth, 
especially with lousy soil. The EARTH connection does NOT CARRY 
POWER CURRENT. The HOT and the NEUTRAL do that. 

The "coil" at the base of the pole sounds like lazy 
electricians to me. 

The ground rod at the power system entrance IS very important.

See http://audiosystemsgroup.com/publish and study the tutorial 
on Power and Grounding for Audio and Video. It explains a lot 
about how power systems work. I'm nearly finished with an 
international version. BTW -- I also wrote the Grounding 
section in K7LXC's new book on towers. 

Ken Kopp said:

>As others have said .... NEVER use the "U" hole in the
>outlet for a wrist-strap or anti-static mat connection!

"Others" are wrong. BY LAW, the U hole must be a solid ground 
carried from the power system service entrance. As long as that 
connection is there, it is PLENTY good enough to discharge 
static. 

>Mine goes to the station ground buss ... 2" wide CU 
>strap ... that's connected directly to a number (12)
>of 8' ground rods that are all bonded together with #8
>CU wire.  There is no connection between this ground
>system and the power company's entrance ground.

And you are DEAD WRONG. BY LAW, ALL GROUNDS MUST BE BONDED 
TOGETHER. To do otherwise is UNSAFE. 

>There is often measurable potential between the white
>neutral wire, the green "ground" wire and a ground rod.

There MUST be measureable potential between the white (neutral) 
wire and the ground wire -- the neutral carries the current of 
the load, the green ground wire must NOT carry that current. 

>In some parts of Canada there is just one wire used in
>the power distribution, especially in rural areas.  The
>earth is the other side of the distribution circuit.  

That's also done in Australia, but only for HIGH VOLTAGE 
distribution (tens of kV) (which has proportionally lower 
current for the same power), not for local distribution. The 
earth is FAR too lossy (resistive) to do that for low voltage 
(120V/240V/480V). 

>This was the case for rural phone lines in the US in the past.

Not quite. The use of the earth was for signalling (ringing), 
and was balanced (called simplex, similar to "phantom power" 
used to power professional microphones on balanced cables). An 
audio frequency loop with a single wire and earth as a return 
would be VERY buzzy, because it picks up the magnetic field of 
the power system and the 3-phase noise current in the earth. 
W8IHY and I did that around 1957 between our houses that were 
about three city blocks apart (in Huntington, WV). It was very 
buzzy. :) 

Many major misconceptions have been thrown around in this 
thread. Some of you guys need to study my power and grounding 
tutorial. 

73,

Jim Brown K9YC