why 3 phase electricity instead of 4 or 5, etc?

Question

why 3 phase electricity instead of 4 or 5, etc?

In: 1

Answer 1

Efficiency vs Cost

Single phase power takes 2 wires and has 70.7% efficiency. The voltage is low in parts of the cycle.

Three phase power takes 3 wires and is 93% efficient. That’s a big improvement for 50% more wires

Four phase might be 99% efficient, for four wires. That’s not much improvement for 33% more wires.