On our house we have a 3 pole / 3 phase main breaker but then everything else is 240v single phase inside the house, what sort of wiring connection happens between the 3 phase power and the rest of the house?
In: 1
Along with the 3 phases you will also have a neutral.
The 3 phase system can come in 2 different configurations, regsrding how you connect stuff. Referred to as “star” and “triangle”
Star you could see as a Y., the line peaces of the letter are connecttions. Each points of the Y is phase. And the center the neutral. In Europe, the voltage between 1 of the points and the center will be 230v. So one socket is between the centre and left top of the Y, the other socket between center and bottom of the Y, the third between center and top right etc. So each connection is 1 phase + neutral. Ideally the load (power demand) on all phases is the same. In that case there will be no current flowing through the neutral line. If there is an imbalance between the loads, there will be a current on the neutral. For this reason electricity companies will split connections evenly over the phases and not put an entire street on the same phase.
In Triangle, or Delta, it is in the form of a triangle and you don’t have a neutral. Your connection is between two phases, so between 1 and 2, 2 and 3, 3 and 1.
This results in not 230v, but 400v. Which is very useful for larger machines etc. However, both lines in the socket in this case are live and can shock you… where in star only 1 is live. (Unless te star is not completely balanced, in that case there is a small current in the neutral and thus also a small voltage compared to ground).
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