Utility meters measure electricity, water or gas.
Under trade measurement laws, specified electricity and water meters used for trade (bill for usage) must be:
- pattern approved
You use a meter for trade if you use the measurement to determine the amount to pay for a transaction, even proportionally.
Pattern approval assesses the meter design to ensure it is:
- fit for purpose
- able to operate in the environment in which it is expected to be used
Your meter design can be examined by:
We evaluate the test results from the examination and decide whether to approve the pattern of the meter. Once approved, we issue a certificate of approval:
Expired or cancelled certificates of approval
You can install and use a meter for trade with an expired or cancelled certificate of approval as long as:
- the Certificate of Approval was valid at the time the meter was manufactured and the National Measurement Institute (NMI) has not withdrawn the certificate
- the meter is verified
A Utility Meter Verifier must test and verify a utility meter before it can be used for trade.
The verifier will use the NITP 14: National Instrument Test Procedures for Utility Meters [517KB PDF] [591KB DOCX]. They will assess to see if it is operating within the acceptable error limits. You can’t verify a meter unless it’s of an approved pattern.
Verified utility meters must have either:
- a verification mark
- a certificate of verification
Only Utility Meter Verifiers can apply verification marks or issue certificates of verification.
Utility Meter Verifiers can apply verification marks as specified in the National Instrument Test Procedures for Utility Meters.
Certificate of verification
Utility Meter Verifiers can issue a certificate of verification as specified in the National Instrument Test Procedures for Utility Meters. Certificates include the meter’s pattern approval number (e.g. 14/3/25) and individual serial numbers (ABC123456).
The certificate of verification format is in the Appendix of the NITP 14: National Instrument Test Procedures for Utility Meters.
Repairing or adjusting meters
If you make a repair or adjustment to a verified meter that affects the metrological performance or breaks the metrological seal, the meter must be re-verified before you can use it for trade. While adjusting or repairing, you must not substantially modify the meter to, in effect, create a different meter design or pattern.
Software and firmware updates
You can make software or firmware changes to pattern approved meters as long as these changes do not affect the meter’s metrological performance. The certificate owner (typically the manufacturer) must submit any changes that do affect the performance to us for approval.
You are not required to have gas meters pattern approved and verified under trade measurement laws.
Gas meters may be assessed for pattern approval in accordance with NMI R 137 Gas Meters [715KB PDF] [323KB DOCX].
All electricity meters must be pattern approved and verified if they:
- were installed on or after 1 January 2013
- measure less than 750 MWh per year
Electricity meters are assessed for approval in accordance with NMI M 6-1 Electricity Meters. Part 1: Metrological and Technical Requirements [359KB PDF] [664KB DOC].
If you operate a building or site with multiple meters and use sub-meters for billing, these sub-meters must be pattern approved and verified. You use a meter for trade if you use the measurement to determine the amount to pay for a transaction, even proportionally.
All cold water meters must be pattern approved and verified if they have a maximum continuous flow rate (Q3):
- equal to or less than 4,000 L/h and were installed on or after 1 July 2004
- equal to or less than 16,000 L/h and were installed on or after 1 July 2014
Hot water meters do not need to be pattern approved and verified.
NMI assesses water meters for pattern approval in accordance with one of the following standards:
- NMI R 49 – meters intended for potable cold and hot water
- NMI M 10 – meters intended for large scale, non-potable applications
- NMI M 11 – meters intended for open channel flow measurement
See Pattern approval requirements for these documents.