How do you apply the wye delta transformation in complex electrical circuits?

[Domenico94]

Homework Statement

What can be special cases, in the study of electrical circuits, in which one can not apply wye delta transformation? Can someone graph them in some way?

Homework Equations

The Attempt at a Solution

 

[PietKuip]

The cube with resistors on all sides is an example.

 

[Domenico94]

Alright..other cases instead?

 

[PietKuip]

You can probably figure out how to obtain the resistance between opposite corners when all edges of the cube have equal resistance, but how would you do the general cube?

Other examples are messy nets of resistors, current sources, and voltage sources.