Bismarck client on MDU Schedule 31 Large General. Their interval data shows peak demand of 780kW in July, but MDU billed them for 820kW demand. Utility claims "instantaneous peak" vs "15-minute integrated demand." Is this legit?
Montana-Dakota Utilities interval billing discrepancy
Most utilities use 15-minute integrated demand, not instantaneous peaks. Check MDU's tariff definition of "demand" - should specify averaging period. If it says 15-minute, then 780kW is correct billing demand.
MDU in Billings uses 15-minute demand windows for all commercial accounts. I've never seen them bill instantaneous peaks. Get a copy of the actual meter data download to verify your interval calculations.
Requested formal meter test from MDU. They found calibration error in demand calculation. Meter was reading 5% high on peak demand measurements. Getting 6-month billing adjustment.
Nice catch! Meter calibration errors are rare but when they happen, the billing impact is huge. Always worth requesting formal testing when interval data doesn't match billed demand.
Demand measurement discrepancies require careful analysis of both interval data and tariff definitions. When in doubt, request meter testing - utilities will usually perform calibration verification at no charge.