Found a Sangamo mechanical meter from 1978 still in service at a client's warehouse in Charlotte. Duke Energy is claiming it's been under-registering for years and wants to bill $18,000 in adjustments. The meter still spins and looks to be in decent condition, but I'm wondering about accuracy after 33 years of service. Has anyone dealt with really old mechanical meters and their reliability? Duke's meter shop says anything over 20 years is automatically suspect, but the client swears their usage patterns haven't changed.
Old Sangamo meters - accuracy after 30+ years?
Derek, those old Sangamo meters were built like tanks. We've got some from the early 1980s still running accurately here in Knoxville on TVA's system. The key is the maintenance history and installation environment. A warehouse with stable temperature and minimal vibration could preserve accuracy for decades. I'd demand an independent meter test before accepting any adjustments. Duke's 20-year rule sounds like a convenient excuse to avoid proving actual inaccuracy. The burden should be on them to demonstrate the meter was reading incorrectly.
Terry's right about Sangamo quality. MLGW has some meters from the 1970s still in service and passing accuracy tests. The mechanical components were over-engineered compared to modern meters. However, 33 years is pushing it even for Sangamo. I'd focus on whether Duke can prove when the alleged drift occurred. If they can't demonstrate a specific timeframe, limiting any adjustment to recent years would be reasonable. Also check if there were any facility changes that could explain usage variations - warehouse operations, lighting upgrades, HVAC modifications, etc.