This one still bugs me. Large manufacturing facility in Tulsa, PSO service territory. Three years of bills, everything looked normal except the usage seemed a little low for their size. Turns out the meter had a 200:1 CT ratio but PSO was only applying 100:1 in their billing system. Client had been underbilled for two years to the tune of about $75K. PSO caught it during a routine meter inspection and back-billed them. Could have caught this earlier if I had just questioned why their usage was so low compared to similar facilities. Always verify those meter multipliers folks.
Missed a $75K refund because I didn't question the meter multiplier
Steve that's rough. Had something similar happen with PG&E in California. Client's meter multiplier was wrong for six months after a transformer upgrade. They were overbilled about $40K before I caught it. Now I always request a copy of the meter installation sheet and verify the multiplier matches what's on the bills.
Lewis that's smart - getting the installation documentation up front. I've started doing meter readings myself on larger accounts just to verify the multiplier is working correctly. Takes extra time but saves headaches later. PSO was actually pretty good about working with us on the payment plan for that back-billing situation.
I always include a meter verification as part of my standard audit process now. Avista here in Spokane has had several meter multiplier errors over the years. Simple math check - does the recorded demand match what you'd expect from the kWh usage? If something seems off, dig deeper. Saved a client $25K last year by catching a CT ratio error.