Following with the overall info I was discussing in my previous article: http://hermeticoguitar.blogspot.com/2013/05/accessories-how-to-troubleshoot-noise.html, I made myself with a Low Voltage Detector and a Socket Tester.
The Low Voltage Detector came before and, I tested it on the whole rig, confirming that everything was ok, what probably meant that I had a good ground at home. But I was waiting for that Socket Tester to see if that was really true and, if I had all my gear correctly plugged and... I had some surprise!.
It was harder than expected to get an European Socket Tester for 220V but, I've finally found one I liked in UK, here: http://www.groundology.com/earthing/accessories.
Since, I have an extension sockets rule plugged to the wall socket, then a Phonic 9000E Power Conditioner, then a air schuko cable for each amp and, for one more extension rule, where I plug my two Voodoo Lab Pedal Power 2 Plus to feed pedal effects, and one more extension rule to plug the Zoom Q3HD recorder, I had several spots to test.
I've started with the wall sockets and they had good readings. Then, I've tested the first extension rule and, realized that isn't the same to plug your cord in one or the other way. To have Line (Hot) and Neutral (Cold) in the right side, you have to properly plug your cords.
Look at this picture:
If Line and Neutral are in the proper position and you have a valid ground, the three leds will light .
As soon as your Line and Neutral are swapped, just the right led will light.
Ok. On the wall socket, everything was correct. Then, I've realized that the cord from the extension sockets rule had also that bigger ground so, I plugged that cord with that bigger ground on top and, then, I've read rule' sockets.
You can plug the tester up or down and, you have different readings. In one direction you get the three leds light and, in the other, the right led alone so, there is just one correct way to plug any other thing to that rule!.
I saw that I had my Power Conditioner reversed so, I flipped the cord's plug to plug it in the rule in the right way.
From the Power Conditioner, I've got 8 outputs with an aerial cord ending in a schuko female. I had to test every output cord to determine how to correctly plug the three amps there. I had some reversed, also.
In one of those aerial cords I have one more extension sockets rule (for my pedalboard) and, once more, I had some plugs facing one direction and others facing the opposite one, some were correctly plugged, some were reversed!.
Finally, in that extension rule, I've got one more extension rule plugged, for the recorder and, sockets worked in the opposite way as the previous rule!. What a nice!.
Well, it was easy and quick to do all this, thanks to that awesome inexpensive device.
I don't know how important can be that you swap Line (Hot) and Neutral (Cold) and, if it has any real impact in tone (as any phase issue), as the lack of ground or grounds with different potential have (if some electrical schooled mate wants to chime in, he/she will be very welcome!) but, at least, now I am 100% sure that everything is "in-order" and, that I did everything it was on my hands to get rid of electrical issues.
For sure, I will bring with me this little device to my next gig.