I am not sure you can fix the problem as you say, the problem in inherent with the devices we use.
Using filters, mitigating transfomers and such help indeed.
Everyone has their own way, some for different reasons or for different results.
Don, I had a problem/project that I am just finishing. After months of measuring and consulting with suppport enginneering from Cutler Hammer, we eliminated excess heat from the system, directlty caused by harmonics.
The savings are qiute pleasing.
Dnk...
