Calculating electric motor cable size

[tobias]

How do I calculate cable size for 2x 22kw motors, power factor 0.86. One will be running whist the other one is for standby, but in case of high load both motors can run together, but it's very rare to have high loads.

 

[Pete999]

Calculate as two circuits

 

[fall-apart-dave]

Will they ever surge at the same time, or are they lead & lag?

 

[Darkwood]

Lots of factors to take into account...

Type of starting - DOL, Star/Delta, VFD, Soft start unit etc etc can all effect the wiring size to the motor
Starting duty - With some loads like high inertia loads the extra time taken to get to speed means cables may need to be larger to allow for the longer starting loads.
Installation methods - as with all circuits the install methods may mean derating factors are applied thus larger cables may be needed to compensate.

What are these motors doing exactly, I assume in asking the question then this isn't your normal field so I would be very cautious to taking on this work as so many factors can mean the difference between a installation that is correct and free from nuisance tripping.
What will the front end device be for your short circuit protection of the circuit and what size are you choosing?