[RFI] 2 Questions on Grounding & bonding multiple items

Jim Brown jim at audiosystemsgroup.com
Wed Oct 5 12:12:32 EDT 2016

On Wed,10/5/2016 8:58 AM, Huff David J wrote:
> I am helping a friend setup a station, and I have 2 basic questions on bonding and grounding.
> 1.       We have some GFCI outlets that were showing RF issues, so I added ferrites around the 120Vac wires leading into the GFCI to solve the problem, but someone asked if that violates NEC code.  I am unable to find anything for or against this in NEC, but I am not an expert.  Does anybody know if this is acceptable?  Do I need any specific mounting, banding, or grounding to meet NEC code with ferrites.

It is acceptable. But better to replace the GFCI with one that does not 
have RFI issues.

> 2.       There are multiple HF radios next to each other, and someone had the bright idea of running a single ground wire around the shack, then tied to a single ground rod.  I found during testing that a single ground wire acted like an antenna, causing lots of interstation interference.  Adding ferrites to a ground wire seems to work, but causes some people to question if this is acceptable.

It is not.

>   I realize lightning and high voltage will blow right past the ferrites, but is it acceptable to add a ferrite to prevent interstation interference?  I personally think the people driving this do not understand the concept of grounds, but that is another whole topic.
You are correct.

Study http://k9yc.com/GroundingAndAudio.pdf

What are your antennas?  I would suspect problems there. If, for 
example, you have an end fed antenna that ends in the shack, it needs a 
counterpoise. If it does not, return current from that antenna will flow 
in whatever return path is provided, including the green wire in your 
home, that ground wire, and all the wiring in the shack.

73, Jim K9YC
> Thanks,
> David J. Huff
> W0im
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