A 480 Volt Wye (or Star) has 480 Volts between legs and 277 Volts from any leg to neutral.
It sounds like they tried this 'grab one leg and the neutral' stunt and ended up feeding the panel with 277V instead of 110V, thus frying it.
The math works regardless which side of the ocean you're on. The guy seems to have no clue what he's talking about.
I had a somewhat similar situation with a Japanese guy on a machine that I was installing. I could point things out and explain them until I was blue in the face, but he never wavered from his beliefs. If was funny to watch his face when the machine finally ran exactly as designed while I handed him all the 'required' stuff that he insisted was needed.
