Every new electricity meter or gas meter installed for billing purposes must be approved to MID (Measuring Instruments Directive) regulations. MID legislation came into effect in October 2006 and ran alongside the original Ofgem legislation for 10 years until 2016. In October 2016, MID superseded Ofgem legislation completely.
The Measuring Instruments Directive (MID) is a European directive (2004/22/EC) that corresponds with the requirements of 10 different measuring instrument types, including gas and active electrical energy meters. MID approved instruments have to pass specific conformity assessment procedures and have set MID markings which allow the instruments to be used within the EU.