ANSI C12.1-2022: Code for Electricity Metering

Line up of 4 ANSI C12.1-2022 watthour smart meters.

The total electricity installed capacity in the US hit around 1.4 billion kilowatts at the end of 2021, and the nation’s electrical power industry grows by over $300 million every year. Electrical power and access to electricity is so essential to our lives that it has become a necessity comparable to food and water. Standards change and grow to keep up with the developments in electricity metering. As mentioned in the foreword of ANSI C12.1-2022: Electric Meters – Code for Electricity Metering:

“The Code for Electricity Metering is a body of work that originated over 110 years ago with the first edition released in 1910. Since then, a great many people have dedicated themselves to updating and modernizing this work. This latest edition is dedicated to all the past and present committee members who have demonstrated a passion for Electricity Metering standards development, and upon whose shoulders this latest version stands.”

Foreword of ANSI C12.1-2022

What is ANSI C12.1-2022?

ANSI C12.1-2022: Electric Meters – Code for Electricity Metering is the current edition of the American National Standard that specifies 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.

ANSI C12.1-2022 also deals with the testing and installation of the meters. These address a variety of issues that can naturally be presented to the meters throughout their life usage, such as the effect of radio frequency interference. This gives utilities, manufacturers, and even legislative bodies the ability to secure the usage of meters over time.

Also covered in the ANSI C12.1-2022 standard are accuracy class designations, current class designations, voltage and frequency ratings, test current values, service connection arrangements, pertinent dimensions, form designations, and environmental tests.

Developments in Electric Meters and Impact on the ANSI C12.1-2022 Standard

In the time since the 2014 edition of the ANSI C12.1 standard (which was published in 2016) was revised, the electric meters industry has undergone some significant technological advancements, which are reflected in the current standard. In the North American market, electromechanical meters are no longer manufactured, and tests related to them have been deprecated. There have also been developments in the field of electromagnetic compatibility and auxiliary communications device influence, which have been included in ANSI C12.1-2022.

Changes to ANSI C12.1-2022

ANSI C12.1-2022 revises two standards: ANSI C12.1-2014 (the previous edition of the code for electricity metering) and ANSI C12.20-2015. While ANSI C12.20 was previously another standard in this series, its content has been merged into ANSI C12.1, so there is now a singular document that covers the entire code for electricity metering. Blondel and non-Blondel meters are both covered by this new version of C12.1. C12.20 will be withdrawn with the publication of this version of C12.1.

Anyone interested in the past edition of ANSI C12.20 and the new ANSI C12.1 can get them together as the ANSI C12.1 / ANSI C12.20 – Electric Meters Set.

Specific major changes made to ANSI C12.1-2022 include:

  • Polyphase loading was mandated for all type testing of polyphase meters
  • Voltage tests for meters with wide input voltage ranges were simplified
  • Test No. 4: Effect of variation of power factor was greatly simplified
  • Test No. 7: Equality of current circuits was simplified
  • Test No. 10: Effect of register friction was deprecated
  • Test No. 12: Effect of tilt was deprecated
  • Introduction of the Critical Change Value concept for certain External Influence tests
  • Test No. 17: Effect of high-voltage line surges was modernized
  • Test No. 18: Effect of external magnetic field was modernized
  • Test No. 26: Effect of radio frequency interference was modernized
  • Test No. 28: Effect of electrostatic discharge (ESD) was modernized
  • Tests 39 through 44: Harmonic Influence were carried over from ANSI C12.20
  • Appendices A and B were modernized
  • A section on non-Blondel metering was added to Appendix A, “Measurement of Power, Energy, and Related Quantities”

How Does ANSI C12.1 Relate to ANSI C12.10?

Another American National Standard in the series of standards for electric meters, ANSI C12.10-2011 (R2021): Physical Aspects Of Watthour Meters – Safety Standard, covers the physical aspects of detachable and bottom-connected watthour meters and associated registers. In its scope, ANSI C12.1-2022 states:

“Where differences exist between the requirements of this standard and the most current version of ANSI C12.10, the requirements of this standard shall prevail.”

What About Smart Meters?

Smart meters, which are being installed nationwide, offer numerous key benefits for customers, the state, utilities, and even the environment. In 2020, U.S. electric utilities had about 102.9 million smart metering infrastructure installations. The rapid installation of these meters is considered the first step toward developing smart grids, in which digital technologies are applied to every aspect of the industry, from generation, to transmission, to distribution, to the customer interface.

Currently, the infrastructure for a smart meter type system is covered by several standards in the ANSI C12 series:

ANSI C12.18-2006 (R2016): Protocol Specification For ANSI Type 2 Optical Port

ANSI C12.19-2021: Utility Industry End Device Data Tables

ANSI C12.21-2006 (R2023): Protocol Specification For Telephone Modem Communication

ANSI C12.22-2012 (R2020): Protocol Specification For Interfacing To Data Communication Networks

These standards, ANSI C12.1, and other meter standards are available as part of the ANSI C12 Smart Grid Meter Package.

ANSI C12.1-2022: Electric Meters – Code for Electricity Metering is available on the ANSI Webstore.

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