Why do shaver sockets accommodate round pin plugs in the 115V outlet when countries with 100V to 120V mains supplies use type A plugs with flat pins? Is there a country somewhere with a 100V to 120V mains supply that just so happens to use shavers with round pin plugs?
In North America where both HV and LV on the same pole seems to be the norm, the usual practice appears to be to use three separate single-phase transformers, each with a single HV bush connected to a phase. The three transformer tanks are connected together and to an earth electrode. At least in this case with there being a 3-phase supply, the overall earth current will only be the out of balance HV neutral current. In Pusan, South Korea, another user of Single Wire Earth Return, it was normal to see Variacs (variable transformers) in bars and cafes so that as the transformer load increased and the LV dropped, the Variac could be adjusted to increase the voltage so as to keep the lights at their required brilliance.
In North America where both HV and LV on the same pole seems to be the norm, the usual practice appears to be to use three separate single-phase transformers, each with a single HV bush connected to a phase. The three transformer tanks are connected together and to an earth electrode. At least in this case with there being a 3-phase supply, the overall earth current will only be the out of balance HV neutral current. In Pusan, South Korea, another user of Single Wire Earth Return, it was normal to see Variacs (variable transformers) in bars and cafes so that as the transformer load increased and the LV dropped, the Variac could be adjusted to increase the voltage so as to keep the lights at their required brilliance.
