What is an inventory?

The unmetered customer should provide an inventory listing the connected equipment by location, Charge Code and Switch Regime.  A full list of all the Charge Codes and Switch Regimes is published on the ELEXON unmetered website. The format of the inventory will be agreed between the customer and the UMSO, a standard inventory format acceptable to all UMSOs can be found in the Operational Information Document (section 8) published on the ELEXON unmetered website.  For new housing developments this may be by provision of a street lighting layout drawing in place of the inventory.  The drawing is converted into appropriate Charge Codes and Switch Regimes to enable energy usage to be determined.  A summary inventory is provided on the UMS Certificate.

Charge Codes are 13 digit numbers which identify the connected equipment and the circuit watts that will be used in the energy consumption.  Switch Regimes are 3 digit alpha-numeric codes that identify the equipment operational hours.  Both these values are used to determine the energy usage.

The customer is required to update the UMSO with any changes to the inventory.  A standard inventory file format is defined in the unmetered Operational Information Document (section 8) published on the ELEXON unmetered website.  In the absence of a regular update the UMSO will request confirmation of any changes at least annually.

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.

HID lamp and cones
Inventory Schedule

UMSO - Unmetered Supplies Operator