How often do meters need to be re-calibrated?

Issue
Do meters require periodic re-calibration and if so, how often?

Produce Line
Power Metering

Environment
Meter calibration and accuracy

Resolution
All meters are calibrated at the factory to ensure they comply with published accuracy specifications. They do not require periodic re-calibration nor should they need to be re-calibrated over the operational life of the meter. However, some meters may experience an accuracy drift over time due to environmental or other unknown factors. If a meter is suspected to have drifted outside of it's published accuracy range, it can be sent back to the factory for re-calibration and certification.