Three-phase current is three-phase alternating current. The three phases of three-phase current are 120 degrees out of phase with each other. The difference to single-phase alternating current lies in the alternating voltage
and the transmittable current power, since each individual phase can carry as much current in terms of power as the one phase of alternating current. Since AC electrical power is almost always generated in three phases, power transport in high-voltage grids, medium-voltage grids, and low-voltage grids is also always three-phase all the way to the end user, whether an industrial facility or a residential building. Each of the three phase shifted voltages of the three-phase current has an effective voltage of 230 V with respect to the neutral conductor. The effective voltage between any two phases is 400 V. Consumers can use the 230 V or the 400 V, depending on the connection
. The supply of terminal equipment with high power consumption is much more efficient with three-phase three-phase current than with single-phase alternating current. As far as end appliances in residential buildings are concerned, instantaneous water heaters, electric ovens and heat storage units, among others, are connected directly to three-phase current. An advantage of three-phase current also lies in the simpler wiring, as no neutral conductor is required for three-phase connections. On the other hand, for normal household appliances, you can only connect one phase with neutral and have a mains voltage of 230 V.