Complexity of a HAM shack safety earth (ground)

  It has been a while. Unfortunately personal things happened. And we all got covid-19. So, we had some difficult times the last 2 weeks. Hope to pick up writing again anyway.

Due to being not able to get to my job I had some free time after I had some health issues due to the virus. I decided to do some work in the shack. Something I should have done months ago. But....no time and didn't feel like I had to do it. Might be not to urgent although the problem I want to write about gave some serious safety issues.

For the last couple of months I had serious problems to get power into the shack. When switching on the mains the earth leakage circuit breaker would trip most of the times. Unfortunately replacing the switches wasn't that easy so the problem was getting worse in time. It was indeed that worse that at some moment I couldn't even switch power off because the contacts were simply welded together! Well, I finally had some time to take a closer look. As seen on the photo, the switch was not repairable. I didn't want to use the same switches as well because it is evident that they are not good for this task.

I did invest in some better switches. Of course they cost at least 5 times more as these simple switches. But hope they are a lot better. Previously I switched both L and N. Now I only switch the live wire.

The photo shows when I just removed the old switches. I use one switch to power on the computer and other appliances. The other switch is for the transformers feeding only the transceiver. The PSU in use is galvanically not connected to the mains of the house. It is separated by a 1:1 transformer. I really don't know if this helps to minimize interference for all kind of switching transformers on the mains net. But at least I like to believe so.

The new switches are installed now. I also renewed the cabling. I have to say it looks very nice but different from what I use to have installed. I did a search in my archive and found some post I made in 2013 about the electricity in my shack: https://pe4bas.blogspot.com/2013/08/radioshack-update-6-electricity.html

Another issue I had was with my safety earth system. Since I do power my transceiver through a "safety" transformer I don't use the house safety earth system. However, the computer does ( I thought it didn't). I also have a separate earth rod outside especially for the shack which is connected with a thick copper cable to the coax entrance patchpanel near the wall. It is not a RF ground but just for safety in case of static or worse a direct lightning hit into the tower. What happens is when I want to plug in the USB cable from the computer to the IC-7300 I get shocked! I measured why and there is at least 100V between my computer and my IC-7300. Clearly this is a earth potential problem, as long as the USB cable is connected there is no problem because everything has the same potential. I didn't have a simple solution for it since whatever I thought I should do it would give me a groundloop which I want to prevent. I didn't want to disconnect the house safety earth from the computer as well. The main problem in a HAMshack is probabely the outer screen of the coax, since that is also a conductor and connected to everything earthed from your transceiver. I actually used it as my "safety" earth and did not connect the starpoint of my counterpoise/RF earth to the earth rod because it would make a groundloop. But what if I disconnect the coaxcables from the entrance patch panel? In that case the earth connection would be gone. A dangerous situation in case of a malfunction. Yes, the USB cable would still ground my radio to the house "safety" earth. You see, but what if....the question kept playing in my head. Even reading my own article about the subject didn't give me the right "feel".

In the end I think for a good safety earth everything should have equal potential. You can only get that by bond all wires together and don't rely on the outer screen of your coax cables and yes it will give you groundloops. And yes, I know the separate groundrod should be connected to the house safety earth groundrod to prevent these kind of problems. But unfortunately this is impossible since I have no access to the house groundrod. I decided to minimize the groundloop effect by using a few #31 material ferrite clamps at least every meter and wind the earth wires through it. At the moment I have permanent earth wires to the wall socket of my computer and connected both house safety earth wire to my shack ground as well as the starpoint of my counterpoise. The PSU is grounded to the starpoint and again used ferrite to break groundloops. 

Finally the 100V difference between computer and TRX is gone now. I didn't notice any difference in receive or transmit yet. But didn't try all bands yet either. At least I feel a little safer now, though in a few years I could have a different view on this complicated matter.

Sorry if you find this blogpost a bit chaotic. It looks like the virus has blurred my mind. The whole installation of the switches and adding a few earth cables took me at least 2 days. Normally it would only took me a few hours. I had to think long before every step.

Update 21-12-2021: 

I'm more and more convinced I'm on the wrong "earth" path. Not only that but considering electrical installations differ in other countries it is quite dangerous to write about something like a safety earth. What works well in the Netherlands can be dangerous in the UK or the USA or any other country. I suggest to read MW1CFN's blogpost about some dangers of misunderstanding protective earth. At first I was thinking about deleting this post. However, I leave it as it is since I want to work to a safe solution for a safe earth. For now I warn everyone not to modify your home electricity wiring including the safety earth which is part of the whole installation. 

However, many HAMs use a separate groundrod for their shack. What to do with it? Read my post from 2013 why I wanted something like a separate ground in the first place:

https://pe4bas.blogspot.com/2013/08/shack-rf-ground.html

But in time it only gave me questions. Is it really necessary to have something like a separate groundrod for your shack if a house safety ground is already there?