[RFI] w7ekb & ground rods

[EDWARDS, EDDIE J]

Rik, 

In quick scan couldn't find anything on NEC Article 250 supporting your statement.  Did you find anything in 250?  I only found a reference to "6 ft minimum" distance, but that might be old reference and depend on length of the ground rod.  This makes sense for NEC since it's worried more about AC electrical safety not RF grounding.  In comm buildings R56 calls for using both an underground ground ring/buss and bonded ground rods as a single system bonded together.

However, your statement about rods closer than twice the length being unproductive is true.  It is a waste of money and has little effect on ground resistance, but I doubt it does much harm if any overall.  And the "two-times length" maximum is also true.  

I'd rather have any and all above ground, bonding connections from/to each service (AC, cable TV, ham radio, telephone) as short of a run as possible to the earth (e.g. buried, bonded ground rods) even if that meant the 8 ft rods were only 6-8 ft apart.  This would be required for an RF single point ground system as I know it.

These are interesting NEC links for those with time on their hands:

http://www.necconnect.org/resource/?Id=1000027&Asset=c67370a9-8aa8-4606-a9c9-bb631a89c2e2 

http://fyi.uwex.edu/mrec/files/2011/04/W4.-Biesterveld-NEC-grounding-MREC2010.pdf 

73, de ed -K0iL

-----Original Message-----
From: RFI [mailto:rfi-bounces at contesting.com] On Behalf Of Rik van Riel
Sent: Saturday, January 17, 2015 11:09 AM
To: rfi at contesting.com
Subject: Re: [RFI] w7ekb & ground rods

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Hash: SHA1

On 01/15/2015 04:45 PM, EDWARDS, EDDIE J wrote:

> Excellent point Jim.  All services' grounds (AC, telephone, 
> television, internet and ham shack cable entry point & ham tower) 
> must be bonded to a single-point ground system.  There's no limit
> on number of ground rods as long as they're bonded (i.e. tied to
> the same grounding system).  8 foot ground rods need to be within
> 16 ft of each other, but can be closer if needed to shorten cable
> run to each service ground connection.

I thought NEC specified the opposite, specifically that
ground rods had to be at least twice their length apart,
in order for each rod to have its own independent
connection to ground.

In other words, ground rods spaced closer together than
twice their length will not result in as large a reduction
in ground resistance as ground rods spaced the recommended
distance.
- -- 
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