Plastics manufacturer, ~$8K/month electric. NC requires a predominant-use study from a licensed PE. Quoted $3,500-$5,000 for the study. Sales tax is 7% so refund pool over 36 months lookback is ~$20K plus go-forward savings. Has anyone done one of these end-to-end — any gotchas with the NCDOR review process I should warn the client about?