Mitchell from Amarillo. Client's tariff specifies demand measured in 15-minute intervals. The utility has been billing demand based on 30-minute intervals. In months with brief demand spikes this distinction matters because a 15-minute spike spread across a 30-minute average looks smaller. Found this only because the client happened to have a logger recording at 15-minute resolution. Has anyone else found interval granularity errors?
Demand charge dispute — 15-minute vs 30-minute interval granularity
Walt. This is a real error and the billing should follow the tariff. If the tariff says 15-minute intervals the utility must use 15-minute intervals regardless of their legacy billing system configuration.
The utility's response was that their meters only record at 30-minute intervals for this account class and that the tariff language refers to the measurement capability of the billing period not the actual interval resolution.
Mike D. That is a creative but weak argument. The tariff language specifying 15-minute intervals exists precisely to limit demand to actual 15-minute peaks. If their meters cannot measure 15-minute intervals for this account class they need to upgrade the meters.
Derek. File a formal complaint with the PUC citing the tariff language. The utility's meter configuration limitations are their problem to solve, not a reason to override tariff language in their favor.
Filed the complaint. PUC agreed the tariff was clear and ordered the utility to replace the meters with 15-minute capable units and recalculate demand for the prior 18 months using reconstructed 15-minute data where available.