not at risk of becoming live should any overhead distribution conductor be fractured by, say, a fallen tree or branch. In pre-RCD era, the TT earthing system was unattractive for general use because of the difficulty of arranging reliable automatic disconnection (ADS) in the case of a line-to-PE short circuit (in comparison with TN systems, where the same breaker or fuse will operate for either L-N or L-PE faults). But as residual current devices mitigate this disadvantage, the TT earthing system has become much more attractive providing that all AC power circuits are RCD-protected. In some countries (such as the UK) TT is recommended for situations where a low impedance equipotential zone is impractical to maintain by bonding, where there is significant outdoor wiring, such as supplies to mobile homes and some agricultural settings, or where a high fault current could pose other dangers, such as at fuel depots or marinas. The TT earthing system is used throughout Japan, with RCD units in most industrial settings or even at home. This can impose added requirements on variable frequency drives and switched-mode power supplies which often have substantial filters passing high frequency noise to the ground conductor. IT network In an IT network (isolé-terre), the electrical distribution system has no connection to earth at all, or it has only a high-impedance connection. Comparison Other terminologies While the national wiring regulations for buildings of many countries follow the IEC 60364 terminology, in North America (United States and Canada), the term "equipment grounding conductor" refers to equipment grounds and ground wires on branch circuits, and "grounding electrode conductor" is used for conductors bonding an Earth/Ground rod, electrode or similar to a service panel. The "local" Earth/Ground electrode provides "system grounding" at each building where it is installed. The "Grounded" current carrying conductor is the system "neutral". Australian and New Zealand standards use a modified protective multiple earthing (PME ) system called multiple earthed neutral (MEN). The neutral is grounded (earthed) at each consumer service point thereby effectively bringing the neutral potential difference towards zero along the whole length of LV lines. In the IEC 60364 terminology this is called TN-C-S. In North America, the term "multigrounded neutral" system (MGN) is used. In the UK and some Commonwealth countries, the term "PNE", meaning phase-neutral-earth is used to indicate that three (or more for non-single-phase connections) conductors are used, i.e., PN-S. Resistance-earthed neutral (India) A