I would complain to the power company, 524 vac is too high, way too high. They need to adjust the taps at the substation.
The highest taps on those is 504V, that will not fix his 524V service problem. For that he needs to call the utility service commission in his state, if the utility refuses to fix the problem.
In my experience this is one of the things they don't try to wiggle out of, even if it's just one small customer. It's too easy for the customer to test and show that they're outside of their public utility requirements. If they don't respond and you call the utility commission, they will still have to fix it, and deal with all the utility commission red tape as well.They're not going to do anything, we are the only ones complaining. 🤷♂️