harmonics

That is not universally true. If you go line to line and not line to neutral, then the third harmonic voltage, assuming symmetrical drive and loading, there will be no line to line voltage at the third harmonic.

Bill

-- If there is such a thing as intelligent design, please explain hemorrhoids.

Clarify your question- are you dealing with a transformer? Then it will depend on the connections on both sides including grounding. Ground or a delta winding provides a path for triplen harmonic currents. Transformers are the major source of triplen harmonics.