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Author Topic: Copper pipe ground bus - QST article?  (Read 32821 times)
DL8OV
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Posts: 1054




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« Reply #15 on: April 04, 2015, 01:43:52 AM »

Add me to the list of copper pipe ground bus users. In my case it's a 30mm copper pipe with each piece of equipment attached using a length of copper braid and a 'P' clip.

Peter DL8OV
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W6UV
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Posts: 1092




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« Reply #16 on: April 04, 2015, 04:00:11 PM »

I would assume using a ground bus helps for lightning protection but if your antenna were struck by lightning I would think your equipment is toast with or withour a ground.

The goal of good station design is to keep lightning energy out of your shack. If you let it in, a ground bus isn't going to save your equipment.
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W8JI
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« Reply #17 on: April 06, 2015, 05:18:25 AM »

I would assume using a ground bus helps for lightning protection but if your antenna were struck by lightning I would think your equipment is toast with or withour a ground.

The goal of good station design is to keep lightning energy out of your shack. If you let it in, a ground bus isn't going to save your equipment.

That is exactly correct.

I have virtually no ground bus at all inside, and never have had one ON MODERN RADIOS. I don't use one in my contest station where multiple radios run at the same time, or in the house.

I DO use ONE IN MY OLD RADIO DESK. Old tube radios use a two wire cord and have line bypasses that make the chassis hot, so they need that safety ground.

New radios do not. They have three-wire cords or polarized plugs, or run from 12 volts.

The desk ground bus will not cause a ground loop, it will reduce chances of a ground loop, but it is largely unnecessary.

Lightning protection does not work at the desk. Lightning protection only works effectively at the cable entrance to the building and room. The same is generally true for RF burns and such, although an improper antenna system or poor wiring that causes RF burns can be band-aided by a desk ground bus.

Because of my tower height, I get a lightning hit almost every thunderstorm. I never get internal damage, and I never disconnect. 

http://www.w8ji.com/ground_systems.htm

 


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W3TDH
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Posts: 17




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« Reply #18 on: June 17, 2019, 04:00:05 PM »

I'm still don't understand why equipment must be grounded. We know there are three types of grounds: RF, electrical and lightning.  I would assume using a ground bus helps for lightning protection but if your antenna were struck by lightning I would think your equipment is toast with or withour a ground.  I've read pro and con on this.  The ARRL handbook says not to ground equipment if your shack is on a second floor (which mine is) so I don't use a ground on my equipment.

Can someone shed some light on this?

Phil
K1PJR
It is true that it is not possible to prevent a voltage rise on your equipment relative to the earth at some distance from the strike but you don't need to.  What you do need to do is to have all of the equipment go on that wild dance to the same music and steps.  The only thing that will cause a destructive current flow through your equipment is a difference in potential between them.  You really don't need to care if the whole station goes to some phenomenal voltage relative to the earth.  What will ruin your day is a difference between the pieces of equipment or any of the conductive pathways which are connected to the equipment.  The whole reason that we bond everything to a single point "grounding" (Actually bonding) busbar is to keep them at or very near the same potential.  The reason that we bond the various protectors for all of the conductors that enter the station operating area to that same bonding busbar is that we need to keep the protectors bonding points at a similar nearly equal potential but only relative to each other. 

--
W3TDH 
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W3TDH
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Posts: 17




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« Reply #19 on: June 17, 2019, 05:40:49 PM »

I used a length of 3/8s inch ID copper tubing for station grounding once. It had several wire "straps" soldered to the tubing spaced equally. It worked fine.
Now I use a single point grounding for the station. A thick copper round plate with heavy braided copper straps that connect the gear to the plate, which is connected to the outside ground rod directly with a single run of 6ga wire.
You must also understand that station grounding serves only two functions. 1. RFI suppression and prevention. 2. Electrical safety grounding.
It is NOT lightening protection. No grounding system in existence can protect your station during a direct lightening strike. Even a nearby strike can induce huge voltages in your station ground system and damage the gear.
I disconnect my station from outside grounds when the station is not in use. Isolating the station from the outside world has protected it so far from several nearby strikes that damaged TV gear in my house. There was no damage to any ham gear.
I re-connect the ground when I'm operating the station. I made it easy, I use a large alligator battery clip that connects a heavy copper braid from the station single point ground plate to an outside grounded plate mounted on my shack wall, well away from my gear.
So far, no RFI, no RFI issues of any kind. No electrical problems, ground loops, etc. My deactivating protocol has protected my gear from numberous nearby strikes.
I think it works. 
 

This belief that there is no practical protection from a direct strike is not born out by the experience of the broadcast industry, emergency communications centers, cellular system operators, electrical utilities, and the list goes on.  A carefully installed least cost grounding electrode system, single point ground busbar for the protectors on conductors that enter your station, and a single point bonding busbar at the operating position does not have to break the bank and if you do it carefully and follow best practices you can have the same resistance to lightning that those activities enjoy. 

--
W3TDH
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