In-service testing group 3 report

In-service testing governance arrangements for gas and electricity meters.



The Industry Metering Advisory Group (IMAG), sponsored by ELEXON and Ofgem, set up the in-service testing (IST) and post-Measuring Instruments Directive (MID) expert group (IST 1), to develop proposals for the in-service accuracy monitoring of MID approved domestic type gas and electricity meters. A further expert group (IST 2) was subsequently established to develop additional proposals to ensure the other legislative requirements aside from meter accuracy were also covered.

The combined proposals of these groups were published in the IST group 1 and 2 report that was accepted by IMAG and Ofgem in 2008. These proposals set out a methodology based on sample testing whereby energy suppliers and asset owners can demonstrate they are fulfilling their statutory obligation to keep their meter populations in proper order for correctly registering the quantities of gas and electricity consumed.

A further expert group (IST 3) was then established to consider the costs of the IST scheme and possible governance arrangements. The findings of this group were published in the IST group 3 report in 2009. IMAG and NMRO then published a joint consultation on the governance options and, following the transfer of responsibility for the metrological performance of gas and electricity meters from Ofgem to NMRO, it was agreed that NMRO would assume responsibility for governance of the IST scheme.


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

Gas and electricity metering team: In-service testing

Utilities Business Team
National Measurement Office
Stanton Avenue

TW11 0JZ