[Elecraft] Ground Strap

Mon Oct 7 13:10:01 2002

Paul,

Let me second what George has said.

What you are proposing has a few problems.

First, with a ground system, your goal is to remove voltage surges (lightning, power 
events) from the equipment rather than distribute them. With this in mind, you want 
the "star" or "single point" wiring method. With what you are proposing, a "problem" 
on one piece of equipment will be shared with all of them on your "buss" rather than 
delivered to the closest ground. Stated another way, a surge has to flow by your 
other equipment to get to ground. You don't want to do this.

Next problem is that you will create a serious single-point failure issue. If you buss 
fails at any one point in your distribution wiring, other components will be at risk and 
will be left unprotected.

Lastly, this approach runs afoul of NFPA and NEC specs.

Bottom line suggestion. Establish a low resistance ground (< 5 ohms), and use a #2 
stranded cable to bring your ground to a copper distribution plate. Use #6 (solid or 
stranded - I suggest stranded, it is easier to install) jacketed wire to ground each 
piece of equipment to the distribution plate.

For great specs, see NFPA 70, NEC Section 250, and a very practical document put 
out by Motorola called R56, which brings all these specs, practices, and procedures 
into one document.

Chuck - n6dbt

Note George, W5YR's stunning brilliance and Chuck's apt reply (gack!)

From:           	"George, W5YR" <[email protected]>
Organization:   	AT&T WorldNet Service
To:             	[email protected]
Copies to:      	[email protected]
Subject:        	Re: [Elecraft] Ground Strap
Date sent:      	Mon, 07 Oct 2002 11:17:57 -0500

> Look at dealers who handle craft supplies and sell copper sheet of various
> widths in rolls. You will probably have to piece together several pieces to
> make the entire run.
> Also building supply houses might carry small rolls.
> 
> From an engineering viewpoint, the distributed equipment ground that you
> describe is not as good as the "star" ground system in which a separate
> conductor runs from each piece of equipment to a central "ground" point.
> Sounds like your layout would not permit this, however.
> 
> The piece of gear at "the far end" can be at some r-f, a-c and audio
> potential above the piece nearest the actual "ground" connection with the
> serial layout you want to use. This largely tends to defeat the use of a
> station ground arrangement in which you want the chassis, etc. of all
> pieces of gear to be at the same potential.
> 
> 73/72, George    
> Amateur Radio W5YR -  the Yellow Rose of Texas
> In the 57th year and it just keeps getting better!
> Fairview, TX 30 mi NE of Dallas in Collin county EM13qe
> K2 #489      Icom IC-765 #2349     Icom IC-756 PRO  #2121
> 
> 
> [email protected] wrote:
> > 
> > George,
> > I will not be running all that far to ground, I need the length to connect
> > roughly 27 linear feet of radios.  I'm planning to hop from one radio to the
> > next with ground strap (flattened, soldered, and then the hole drilled through
> > the strap for the ground lug). From there, it's on to the cold water pipe and
> > earth ground only 8' away. Thus, at minimum, I'll need 35'.
> > 73
> > Paul
> 
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