The National Measurement Institute (NMI) plans to lift the current exemptions for electricity meters and will introduce new legislation on 1 January 2013. The new legislation will remove the current exemption for some categories of electricity meter under the National Measurements Act 1960.
The legislation will have a significant impact on the selection of meters to be installed on projects where those meters are to be used for trade, in particular for embedded metering systems where electricity is on-sold by landlords to tenants in shopping centres, commercial office buildings and multi-residential developments.
The lifting of the exemption will apply to:
- Meters with a throughput of less than 750MWh per annum
- Meters in use, or intended for use, for trade.
The exemption will only be lifted for meters installed after a certain date, currently anticipated to be 1 January 2013.
What this means for electrical contractors:
- Meters intended for trade use must not be supplied and/or installed unless they are of an approved pattern, and
- Meters must not be used for trade unless they are verified.
Under the National Measurements Act 1960, you will be committing an offence if you supply and/or install meters which are used or intended to be used to bill tenants, calculate monetary transactions or calculate taxes, if these meters are not pattern approved and verified.
Any existing non-pattern approved meter that is used for trade will have to be replaced with a pattern approved meter when it fails. Furthermore, meters that are not pattern approved cannot be relocated and meters that are pattern approved but not verified, must be verified if they are relocated.
What is Pattern Approval and Verification?
Pattern approval is a process of evaluating the performance of a type or model of meter under various influences and disturbances such as temperature variations, electrical interferences, voltage fluctuations and harmonics. The requirements for pattern approval are set out in NMI Specification NMI M-6 which has been harmonised with the recommendations of the International Organisation of Legal Metrology. NMI-M-6 is a direct reflection of OIML-R-46.
Verification is the process of assessing whether an individual meter operates within the specified limits of error. To be verified, a meter must be of an approved pattern and comply with the certificate of approval. The verification must be performed by an appointed utility meter verifier.
Meters manufactured overseas must be tested in the country of manufacture by an accredited testing and calibration laboratory. Sample testing of a batch of imported meters must be carried out in Australia by an appointed utility meter verifier.
Verification ensures that meters are tested by laboratories accredited by the National Association of Testing Authorities (NATA) and supplied complete with traceable Calibration Certificates. This leads to cost savings where non-utility meters are for National Australian Built Environment Rating System (NABERS) and Commercial Building Disclosure (CBD) certification purposes because each meter is individually calibrated, so there is no need to further prove the meter accuracy; unlike meters designed to comply with IEC 62053 Standards only, which are generally not individually tested or validated.
Why is the exemption being lifted?
Lifting the exemption will bring the requirements for the metrological control of electricity meters into the Australian system of weights and measures under the National Measurement Act in the same way that other industries are regulated. The aim is to increase confidence in the measurement of electrical energy for consumers and industry.
The changes will also introduce national consistency of metering requirements since the National Electricity Rules (NER) do not cover all of Australia, and do not cover all meters used for trade within regions covered by the National Electricity Market (NEM). For example, tenants in apartments, commercial buildings and retail developments with sub-meters may not be covered. In addition, the NER do not require verification, so even if a meter is of an approved pattern, and covered by the NER, there is no requirement for that individual meter to be verified.
Billing errors remain a significant reason for consumer complaints to jurisdictional energy ombudsman schemes. The reasons for these complaints vary and can be related to such issues as unseasonal or unusually high demand, retailer error and sometimes metering errors. In a large number of cases it is necessary for the meter to undergo testing for accuracy, at the customer’s cost, if there is no error subsequently identified. It would therefore be valuable to know whether a meter which is the subject of a complaint had already been tested and verified.
Sub-metering and embedded networks
NMI makes no distinction between meters and sub-meters. Sub-meters (sometimes called ‘private’ meters) are installed downstream from a metered connection point to the local distribution network.
When the exemption is lifted, the National Measurement Act will apply equally to sub-meters, so if you are designing and installing embedded metering networks in buildings and precincts where energy consumption is charged to tenants based on the sub-meters installed, you must comply with the Act.
Which meters can electrical contractors use?
Many electricity meters are already of an approved pattern and are verified.
The exemption has been in place to allow manufacturers and distributors of metering and billing systems to get their meters NMI pattern approved, and to sell existing stocks of non-pattern approved meters.
The NMI (formerly the National Standards Commission) has provided services for the pattern approval of electricity meters since 2001 and has established the system for verification.
The NER make reference to pattern approval for meters installed in the National Electricity Market (NEM), and it has become common practice for utilities to specify that meters must be of an approved pattern in their purchasing contracts.
Many pattern approved meters are available with multiple communications options including:
- ZigBee™ Mesh and ZigBee™ Smart Energy Profile
- RS232 (includes modem power from meter)
- RS485 Multi-drop
- GSM/GPRS Push (initiated by the meter)
- Modbus RTU to allow 3rd Party BMS system integration.
Additionally, pattern approved meters are supplied with large non-volatile memory capacity and, in some cases can store up to 24 years of half-hourly interval data (2 channels), removing the requirement for external data logging and ensuring that consumption data is never lost.
What does this mean for electrical contractors and designers?
Primarily, you will need to consider the spatial requirements for the installation of the meters. At this stage, there are no smart DINrail mount or panel mount meters (96mm x96mm) that have NMI pattern approval. Why? Because you can’t easily fit the necessary electronics required to make a compliant meter, into a 96 x 96mm case.
There are a number of manufacturers currently working hard to try to get a pattern approved DIN-rail meter designed, but it is a difficult task.
Therefore switchboard metering enclosures will need to be increased in size and where meters are installed in subswitchboards or to meter final-circuit distribution boards, riser and electrical cupboards spaces will have to be re-considered.
If you already have an existing non-compliant metering system, for instance, using non-complaint panel-mount meters or DIN rail mount meters, and one of those meters fails after 1 January 2013, legally you will have to replace it with a pattern approved meter. This may cause some installation headaches as it is unlikely that the replacement meter can be fitted in the same space.
You may also have some issues interfacing the new meter to an existing system as there are very few pattern approved meters which have MODBUS or BMS interfaces. Most use highly secure proprietary protocols as required by the utilities.
Summary
The proposed lifting of the exemption on electricity meters will have significant implications for electrical designers and contractors installing sub-metering systems for multi-tenanted developments where there is the intent to on-sell electricity to the tenants.
It will become a legal requirement to supply and install pattern approved and verified meters, and consideration must be made in both building and switchboard design for the increased space required to install these meters.
However, the benefits, in terms of increased confidence in the accuracy and long-term reliability of energy metering systems, outweigh the impact of the increased physical dimensions of the meters.
For more information visit Smart Building Services at www.smartbuildingservices.com.au.