Here you have the possibility to calculate the required cross-section of copper connection cables in
the three-phase network. Normal three-phase loads such as three-phase motors are connected here. 

Attention:
Our cable calculator only generates a rough estimate for the cross-section!

For Example:

A 400 volt three-phase asynchronous motor has a rated current of 25 amps, one
cos φ of 0.89, a cable length of 94 m, and the voltage drop of the cable is 2%.
Which cable cross-section results from these specifications?

A = (√3 x I x L x cosφ) / (K x Δv x V)
A = (√3 x 25 A x 94 m x 0.89) / (56 x 2% x 400 V)
A = (3622.48) / (448)
A = 8.09 mm²

The next larger suitable cross-section is 10 mm²!

Measuring Units:

Cross section     A = mm²
Voltage               V = Volt [V]
Current                I = Ampere [A]
Kappa copper    K = 56 [m / Ω x mm²]
Delta U              Δu =%
cos φ                          no measuring unit 
√3 or 1.732                no measuring unit 

To the product page "three-phase motors"