NEMA Publishes Code for Electricity Metering - NEMA ANSI C12.1-2008

August 19, 2008 // Published as a news service by IHS

This code establishes acceptable performance criteria for new types of AC watthour meters, demand meters, demand registers, pulse devices and auxiliary devices.

It also describes acceptable in-service performance levels for meters and devices used in revenue metering.

According to Scott Weikel, chairman of the NEMA ANSI C12.1 committee, the Code for Electricity Metering continues to provide the basic requirements for both electronic and electromechanical kilowatt hour metering.

It includes information on related subjects, such as recommended measurement standards, installation requirements, test methods and test schedules.

It is designed as a reference for utilities, manufacturers and regulatory bodies involved with the art of electricity metering.

While most of the meter specifications have been retained from the previous edition, several changes were made in the area of surge withstand. Additions to the text clarify test procedures and criteria to pass the tests, said NEMA.

"This version of [NEMA ANSI] C12.1 has been modified in several areas in an effort to respond to a changing industry and to improve the clarity of some of the tests," Weikel said. "The changes, while not extensive, aim to improve the consistency of test procedures and improve the quality of the metering products. This standard continues to form the basic requirement for all kilowatt hour metering instruments - both electronic and electromechanical."

According to NEMA, minor changes to the temperature rise test were implemented to make testing more uniform. Supplementary information was added to the equality of current circuits test, the electrostatic discharge test and the relative humidity test to clarify the testing process. References to external documents were updated.

Another standard in this series, NEMA ANSI C12.20, provides different test tolerances and a few different tests that are required for higher accuracy metering devices.

Source: National Electrical Manufacturers Association (NEMA).