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The most common three-phase system will have three hot legs, 208 V to each other and 120 V each to the neutral. An older, but still widely used, high-leg delta system uses three phases with 240 volts phase-to-phase for motor loads, and 120 volts for lighting loads by use of a center-tapped transformer; two of the phases are 120 volts to neutral ...
As in the UK, 240 V is within the allowable limits and "240 volt" is a synonym for mains in Australian and British English. In the United States [12] [13] and Canada, [14] national standards specify that the nominal voltage at the source should be 120 V and allow a range of 114 V to 126 V (−5% to +5%). Historically, 110 V, 115 V and 117 V ...
They are also found on some RVs for connecting to shore power. RVs in the US are equipped for 120 V 30 A or 240 V 50 A service, and use a cord to connect to a receptacle at the campsite, usually on a power pedestal with one or more receptacles providing 120 V 30 A (TT30R), 240 V 50 A (14-50R), or 120 V 15/20 A (5-20R) service.
However, 130/225 V, three-wire, two-phase electric power discontinued systems called B1 are used to run old installations in small groups of houses when only two of the three-phase high-voltage conductors are used. The phase shift in Europe is 120°, as is the case with three-phase current. That is why we calculate 130 V × √ 3 = 225 V.
The three-wire and four-wire designations do not count the ground wire present above many transmission lines, which is solely for fault protection and does not carry current under normal use. A four-wire system with symmetrical voltages between phase and neutral is obtained when the neutral is connected to the "common star point" of all supply ...
For example, in North America, a unique split-phase system is used to supply to most premises that works by center tapping a 240 volt transformer. This system is able to concurrently provide 240 volts and 120 volts. Consequently, this allows homeowners to wire up both 240 V and 120 V circuits as they wish (as regulated by local building codes).
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This practice arose from the three-wire system used to supply both 120 volt and 240 volt loads. Because these listed appliances often have components that use either 120, or both 120 and 240 volts, there is often some current on the neutral wire. This differs from the protective grounding wire, which only carries current under fault conditions.