The Unmetered Supplies Operator (UMSO) is a role defined by the electricity industry to ensure the arrangements for unmetered supplies are correctly applied. Each electricity network operator appoints an UMSO who will:

  • ensure there is a connection agreement using the National Terms of Connection
  • ensure there is an accurate inventory of unmetered equipment agreed with the customer, and
  • create and update an UMS certificate

An accurate inventory of unmetered equipment is based on trust, but the National Terms of Connection enable an audit regime which is defined further in Managing Unmetered Energy Street Lighting Inventories (MUESLI). The MUESLI document also outlines the process for correcting any identified errors with the inventory.

There are two types of electricity network operators, Independent Distribution Network Operators (IDNO) and Distribution Network Operators (DNO). The 14 DNOs cover 14 defined geographic areas of the country. IDNOs have introduced competition into the distribution of electricity and operate across the country. IDNO networks are often referred to as Embedded Distribution Networks because they are generally embedded within a DNO’s network.

Although Power Data Associates are not formally an UMSO we use our expertise to assist organisations to perform the role. If you would like more information of how we can assist, please contact us. For more information on the UMSO role visit