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Author Topic: Re earlier forum regarding ground wiring in shack.  (Read 222 times)

VK2NZA

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Re earlier forum regarding ground wiring in shack.
« on: September 01, 2020, 05:02:34 AM »

I have been reading through a posting circa Feb/April this year in regard to shack grounding, it was quite detailed and I was interested that most advice was to use braided copper for earthing of equipment to a central copper earthing base and on to ground.
i am not experiencing any common mode current in my shack so no apparent problem, however
 I have though been going to tidy up some of the wiring behind my desk shelf unit housing 8-10 rigs UHF/VHF/HF so there is quite a lot of wiring.

I presently utilise a 3/4" polished copper pipe 14 " long fixed centrally to the wall behind the desk to centralise my earth leads from all rigs and ancilliary items using 2.5mm2 multi-strand covered wire coloured green to iD the wire from others.
They are fixed to the pipe using stainless steel screw type clamps.
The wires do vary in length.

I have recently obtained several meters of 1/2"  diameter woven copper braiding, and intend to replace the multi-strand copper wire, is there an advantage in keeping each individual length the same and does an uncovered earth braid present a worse potential for shorting between equipment in a static charge event?
A full lightening hit would  make this immaterial.
(All antenna's are physically disconnected out side the shack when not in use).

Also the earth from the common equipment grounding pipe utilises approximately 16 feet of copper braid stripped from RG-213 from the 2nd story shack to 3 ground rods directly below.
As has been mentioned in the previous post braid used externally especially can due to corrosion increase resistance.
One poster suggested using copper pipe the full length of the run using short lengths of braid to join each end of the pipe etc. 
I do have enough 3/4 copper pipe to do so ...     
                                                   Any thoughts?
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W9IQ

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Re: Re earlier forum regarding ground wiring in shack.
« Reply #1 on: September 01, 2020, 05:42:15 AM »

I have been reading through a posting circa Feb/April this year in regard to shack grounding, it was quite detailed and I was interested that most advice was to use braided copper for earthing of equipment to a central copper earthing base and on to ground.
i am not experiencing any common mode current in my shack so no apparent problem

Glad that you don't have common mode currents but it is inefficient and often ineffective to attempt to tame common mode current through an earth ground. The use of proper common mode chokes / current baluns is the preferred approach.

I have recently obtained several meters of 1/2"  diameter woven copper braiding, and intend to replace the multi-strand copper wire, is there an advantage in keeping each individual length the same and does an uncovered earth braid present a worse potential for shorting between equipment in a static charge event?

The general concept of this grounding scheme is to attempt to keep all of the equipment at equipotential so that discharge currents don't use a particular piece of equipment as a current path. It also helps to reduce the risk of operator shock during a discharge event.

Most of the energy from a (near) lighting strike is below 1 MHz. So a few inches or centimeters in cable length are a fraction of wavelength from this perspective. There is no inherent danger from using bare conductors for this purpose. Consider that the cabinets to which they connect are also not insulated.

Also the earth from the common equipment grounding pipe utilises approximately 16 feet of copper braid stripped from RG-213 from the 2nd story shack to 3 ground rods directly below. As has been mentioned in the previous post braid used externally especially can due to corrosion increase resistance.

That is correct. The use of unprotected, copper braid is not recommended due to strand corrosion and isolation. This is the same mechanism that causes coax cable that has had water ingress to show increased losses.

One poster suggested using copper pipe the full length of the run using short lengths of braid to join each end of the pipe etc. 
I do have enough 3/4 copper pipe to do so ...

It may be overkill but it certainly would make a good ground conductor. Proper soldering of the joints is essential. If you want a "belt and braces" approach you can also run some stainless steel sheet metal screws or SS bolts with nuts through the soldered joints. Make sure to provide a water drain if your area is subject to freezing conditions.

- Glenn W9IQ
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- Glenn W9IQ

God runs electromagnetics on Monday, Wednesday and Friday by the wave theory and the devil runs it on Tuesday, Thursday and Saturday by the Quantum theory.

WA9AFM

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Re: Re earlier forum regarding ground wiring in shack.
« Reply #2 on: September 01, 2020, 09:05:33 AM »

Get and read "Grounding & Bonding For The Radio Amateur" by Ward Silver, N0AX.  He takes you through the three principle areas of grounding: electrical, lightning protection, and RF.
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VK2NZA

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Re: Re earlier forum regarding ground wiring in shack.
« Reply #3 on: September 01, 2020, 03:13:17 PM »

W9IQ, Hi Glenn,thanks for getting back to me, understood that grounding doesn't neccessarily cure common mode currents, i do have a number of DX Engineering, Balun Designs chokes and baluns in my various antenna feeds.

Take your point re soldering and use of Stainless steel fixtures, i do exclusively use S/S hardware for fastening all hardware in and out of the shack.
I will attempt the copper pipe idea as the length of distance to ground from my upstairs shack is considerable, however do the same wavelength vs length considerations occur with the larger diameter of the copper pipe over say a 15 -20 feet distance.
Glenn freezing conditions are extremely rare in my part of the country, our last winter day here was 28 C or 82 F although the nights cool to maybe 10  c.
Thanks again for your advice, always appreciated,  all the best Ross.

WA9AFM, Hi, I'll have a look online to see if its easily available here.
   All the best , Take care - Ross.
 
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