I am going to 'have two bob each way' here. (Australian slang from gambling on horse racing.)
I think GITRDUN has or had multiple problems:
1) Bad noise problems from outside (another, possibly distant, factory, especially at start-up time in the morning)
2) High leg delta transformer system of dubious parentage
3) Poor grounding (high resistance)
4) Possible lightning strikes somewhere else, maybe
One thing which was emphasised to me many years ago by a grid engineer is that the power grid is not a passive collection of zero-impedance wires linking you to the generators. It is an extremely complex electrical system (yes, with inductances and capacitances) which varies hugely over time as people connect and disconnect all sorts of equipment to it. There can be high impedance points in the network, and low impedance points. Some places will see huge noise spikes while other places see little. And this can change during the day.
Point 2 has been fixed. Point 3 can be alleviated with only a small effort - mainly extra ground stakes, but never entirely solved. It's worth doing anyhow. Point 1 cannot be stopped in itself, although a Ferro Resonant Transfomer will block the effects. Point 4 is also blocked by the FR transformer.
A thought, of no consequence really: if GITRDUN instals a large FRT on his factory, this will change the local grid so someone else may now have problems. Such is life.
Cheers