[RFI] Station ground - more

[Jim Brown]

On Wed,9/28/2016 9:37 AM, Kenneth G. Gordon wrote:
> For instance, when I was wiring our new addition, the wiring included a sub-panel,
> connected to the main panel by a run of #00 4 wire cable. With the assistance of our
> youngest son, we drove an 8' ground rod directly under the sub-panel with the thought that I
> had to connect that to the sub-panel's ground lug.
>
> Yet I was told by the electrical inspector that this was NOT allowed, but that we had to run a
> separate ground wire from the sub-panel at least 30 feet to the main-panel's ground lug and
> connect them together there.
He's partly right and partly wrong. Under the current NEC, you MUST 
carry ground from the main panel. Under older versions, (10 years or 
more) you did not need to carry ground between two buildings (but you 
MUST carry ground everywhere in the same building).  Where he's wrong is 
that you can ADD as many grounds ANYWHERE and connect them to the 
equipment ground (the green wire, which MUST be bonded to the enclosure 
of every electrical enclosure) ANYWHERE in the building. Fundamental 
rule -- you can have as many grounds as you like, but they MUST all be 
bonded together.

> I was also told that the ground-rods we drove (3 ea 8 footers, separated by at least 6 feet
> and all tied together) must be the ONLY such ground system in the entire home,

WRONG

> and that
> every grounded item in the entire home must be connected to that and only to that.
>
> So, why the apparent discrepancy?

He is ignorant of the code. Not all that uncommon -- electricians 
sometimes get to be inspectors by longevity as electricians, or through 
"connections" within the industry.

> For one thing, I suspect that the ~30' long ground wire from the sub-panel to the main panel
> is conducting RF, especially on 40 meters, into some of the electrical appliances in the new
> addition. I also believe that the present ground system in the shack is not adequate, since at
> present it is only being connected to the panel-ground through the green grounding wires of
> the electrical service.

The earth is NOT a sump into which hum, buzz, and RF is poured. A 
connection to earth matters ONLY for lightning protection. Bonding 
(connecting all grounds together) is critical for lightning protection, 
electrical safety (shock, fires), and to some extent, hum, buzz, and RFI.

I've written extensively on this, and the writing is not 
"pronouncements" but is accompanied by discussions of WHY.

73, Jim K9YC
>
> Ken W7EKB
>
> ---
> This email has been checked for viruses by Avast antivirus software.
> https://www.avast.com/antivirus
>
> _______________________________________________
> RFI mailing list
> RFI at contesting.com
> http://lists.contesting.com/mailman/listinfo/rfi
>