Watt-Hour meter certification


Watt-Hour meter certification

Watt-hour meters have typically been owned and maintained by a power company or utilities that supply power to a facility. Generally, this is the case throughout the world. Energy represents a major expense for both commercial and residential customers, and there are pressures from consumers, corporations and politicians to reduce the cost of purchasing electrical power, although the cost of producing power is increasing. The short answer for many is deregulation – and the theory behind this is that competition will result and the cost of buying power will decrease. Well, the jury is still out on this, but deregulation has certainly resulted in one major change – and that is that new opportunities have been created in the market.

Test setup for ANSI C12 meter.JPG

Under deregulation, electric power may be purchased by individuals or organisations and resold to others. Sub-meters allow landlords, owners of shopping malls and the like to make a profit by buying power at a bulk rate and selling it at the small users’ rate. Also, a tenant is more likely to conserve power when he is paying for it separately. Deregulation also opens a large market for meter manufacturers to have a customer base that was not available when the one major purchaser of power meters was the utilities.

In the United States, Canada and several other countries utilities are exempt from many local building and all electrical codes. Local electrical inspectors were often not involved in utility systems, because of their huge electrical networks and unique electrical equipment and apparatus. Electrical inspections of homes and businesses, when required by a country, were usually performed by some municipal or regulating authority.

Electrical inspectors usually look for a mark on electrical products or apparatus in determining that new electrical equipment is safe. Electrical inspectors rely on this mark to attest to the fact that the product was independently tested to national standards. National standards in the US are usually Underwriters’ Laboratories’ standards and in Canada they are CSA standards. Internationally they are known as international standards or ISO standards.


In Europe the CE marking is the required marking that an electrical inspector would look for to determine that the metering device meets national standards. In the US and Canada the mark is that of nationally recognised testing laboratories, accredited by the country. Other countries, such as South Africa and Australia, do not recognise the CE marking system. These countries have their own certification requirements with their own special certification marks.

The major difference between the European CE marking system and the US, Canadian and other country requirements are that the CE marking is a manufacturer’s declaration. No third party involvement is required for a CE mark, and there are no requirements to accredit the manufacturer’s test laboratory. Most other countries require that their country certification mark can only be applied by an accredited third party recognised in that country.

One additional situation as a result of deregulation is that watt-hour meters are now part of a building electrical system and come under the jurisdiction of the electrical inspection authority. Jurisdictional control of electrical systems always started at the primary source of supply to the facility – usually the utility meter. The power company was always responsible for the supply connection, to the utility service, to the meter. The connection from this main service meter to everything within the building was under the jurisdiction of an electrical inspection authority. This means that all sub-meters are part of a building’s electrical systems and are subject to approval by the electrical inspection authority.


MET certification mark.JPG

Electrical inspectors have become accustomed to not considering meters as an item of electrical equipment on an electrical system. Since deregulation, however, an electrical power meter has become part of a building’s electrical system and is therefore now subject to their authority. As increasing numbers of these sub-meters are installed, it becomes more and more likely that inspectors throughout the world will begin looking at watt-hour meters for certification marks.

A watt-hour meter certification programme provides independent assurance that all applicable regulatory requirements have been met. It also assures users that the meters have been certified to meet all requirements for accuracy, environmental stresses, electromagnetic interferences and other international requirements that will be recognised by electrical or building regulators as acceptable in their jurisdiction. Meeting the requirements of the various regulators is becoming more important to customers, and meter manufacturers are seeing the value of obtaining certification for their products.

Standard designations for standards around the world vary, although the requirements are basically the same. Testing to the different standards requires taking into account all of the differences, and ensuring that the tests that are performed cover all the requirements. A list of the primary standards follows. Test and certification to these standards by accredited laboratories will generally ensure that watt-hour meters will be acceptable in any country where the applicable test’s standard is the requirement and the testing laboratory is accredited.

Standards for electrical safety

For electrical safety the standards are basically harmonised, although the designations are slightly different.

US: UL 61010-1,

Canada: CSA C2.22 No 1010-1

Europe and International: IEC 61010-1

Standards for acuracy, environmental streses and electromagnetic compatibility

US, Canada and International: ANSI 12-1 and ANSI C12-20

Europe: EN 62052-11 and EN 62053-2