The "virtual ground" technique we explained operates in order to level the electric potential between the equipments and to avoid them blowing out in the presence of a potential difference. In order to accomplish that one must interconnect the equipment ground wires by means of the voltage stabilizer. The mains plug ground pin must not be cut off as this technique will not work out. Naturally if you don't have a true ground connection, you'll have to let the ground pin of the stabilizer disconnected. That is, the stabilizer will take care of the equipment ground interconnection but its own ground pin will be disconnected.

Several readers asked us to discuss how a true ground can be installed without having to pay for a qualified technician. The most efficient workaround is to look for a metallic point that is connected to the underground of your building. In flats and commercial offices, you may get this point in the water pipe if it is a metallic one, or by means of the building concrete reinforcing bars (note: aluminum window frames will not do it). Therefore just buy a wire with the appropriate length to connect the ground pin of the stabilizer socket to the chosen beam or pipe and voilá, have a nice work!

In case you decide for the water pipe to act as your ground, don't forget to check if pipes are metallic ones, because if they are made of PVC you will not be able to use the piping. Note that, specially in the new constructions, taps are metallic but pipes are plastic. Therefore, take care!

Please do not attempt to connect the stabilizer mains plug ground pin to the mains neutral wire. Unfortunately many people do that. The problem is that if in the future someone wrongly inverts the phase and neutral wires in the distribution frame, your computer will blow up - literally speaking (we've seen this happen).

Another technical detail we forgot to mention in the first part of this series is that we were grounding our discussions on 110 volts mains public utilities. In one of the used configurations, one of the socket pins has a true 220V phase and the other one is the neutral. Else, the other possibility is that both pins are independent 127 volts phases whereas the potential difference between two phases is almost doubled, making up the 220 volts. In 220 volts distributions of this kind, the presence of a ground wire is even more important as the socket may not show a neutral wire (which, as we've seen earlier, has a zero volt potential)