Just looked over some power quality studies and an associated string of emails. The expert commented that the high harmonics on the neutral (49% and 51%, two panels) were a major problem, and required “doubling the neutral”.
Of course, the fact that the actual neutral currents averaged 10-15 amps, and never exceeded 250 Amps maximum (on a service entrance panel rated for, oh, 800 Amps) apparently got by this expert. And the voltage harmonics, 2% maximum on one panel, 3% on the other, were a little elevated, but not in any way problematic.
This, my friends is why I treat every diagnosis of high harmonics as suspect unless I see the data and run the numbers. Because too many people know how to hook up meters, push the “automatic report” button, and jump to conclusions. And not enough people have a clue what it all means.