National sample survey for electricity meters

The national sample survey is used to ensure only meters operating within prescribed statutory limits remain in-service for billing purposes

GB nationally approved meters

The Electricity Act 1989 requires that the majority of domestic electricity meters are certified in accordance with the Act. Certification also forms an important part of consumer protection by helping ensure meters register within the prescribed limits of accuracy.

Where certification is required, meters can no longer be used for billing when the certification period expires. However, the Office for Product Safety & Standards (Safety & Standards) will consider extending the certification period of any meter type where there is sufficient evidence to do so. This evidence can be obtained through the National Sample Survey (NSS) which is carried out following consultation with the industry.

Certain meter types where the certification period is due to expire are selected, and samples of these are tested in a laboratory. For each meter type, if the majority of meters tested are operating within the statutory limits, then Safety & Standards will consider extending the certification period by up to 5 years. Conversely Safety & Standards may decide that the certification period should remain the same or, for poorly performing meter types, that it should be reduced. Schedule 4 is then updated to reflect any changes to the certification period.

The NSS enables suppliers and asset owners to maximise the life of their assets while ensuring that only meters operating within the prescribed statutory limits remain in-service for billing consumers.

MID meters

Safety & Standards, in consultation with the Industry, has developed In-Service Testing (IST) procedures for monitoring the performance of gas and electricity meters approved under the Measuring Instruments Directive (MID). These procedures will enable suppliers and asset owners to demonstrate that they are fulfilling their statutory obligation to keep their meter populations in proper order for correctly registering the quantities of gas and electricity consumed.


If you wish to speak to a member of staff please contact:

Gas and electricity metering team: In-service testing

Utilities Team

Office for Product Safety and Standards
Stanton Avenue

TW11 0JZ

Published 13 March 2014