Current

Phases

Wiring system

Overhead lines

Cables

DC

2 w

1

1

2 w, earthed midpoint

1/4

1

3 w

0.3125

1.25

AC

1

2 w

2/cos²ϕ

2/cos²ϕ

2 w, earthed midpoint

0.5/cos²ϕ

2/cos ϕ

3w

0.625/cos²ϕ

2.5/cos²ϕ

2

4 w

0.5/cos²ϕ

2/cos²ϕ

3 w

1.457/cos²ϕ

2.914/cos²ϕ

3

3 w

0.5/cos²ϕ

1.5/cos²ϕ

4 w

0.583/cos²ϕ

1.75/cos²ϕ