Technical Assurance of Metering Systems


This page explains how Technical Assurance of Metering (TAM) technique monitors the compliance of Metering Systems with metering requirements. The TAM technique forms part of the Performance Assurance Framework (PAF).

The Technical Assurance Agent (TAA)  demonstration

The Technical Assurance Agent (TAA)  hosted a demonstration of the new upgraded TAAMT system, used for the administration of the Technical Assurance of Metering (TAM) audits. Elexon and the TAA walked through the new system and also give TAAMT users an opportunity to ask questions.

How it relates to you

To check the compliance of Metering Systems, the Technical Assurance Agent (TAA) performs an annual audit made up of individual Inspection Visits.

The annual audit consists of a combination of sampled and targeted Inspection Visits to sites with Half Hourly Metering Systems registered in Supplier Volume Allocation (SVA) and Central Volume Allocation (CVA).

The TAA is a BSC Agent commissioned and managed by Elexon. The TAA is currently C&C Group Holdings Ltd.

The TAA auditors are suitably qualified, trained and experienced to carry out Inspection Visits and have the appropriate authorisation throughout Great Britain. All TAA auditors carry copies of their authorisations to Inspection Visits.

The TAA will notify the relevant Registrant and the appointed agents of a Metering System that has been selected for audit at least 20 Working Days prior to the Inspection Visit date.

The Registrant is responsible for securing access to the site and Metering System that has been selected for audit. The Registrant should ensure that a suitably qualified Meter Operator Agent (MOA) can attend.

For High Voltage (HV) sites and for Low Voltage (LV) sites with remote Current Transformers (CTs), the Registrant will also need to ensure that a Licensed Distribution System Operator (LDSO) engineer can attend.

Planning for an Technical Assurance of Metering Audit

Elexon has developed an online support tool to help organise Inspection Visits and share information with the TAA. The Technical Assurance Agent Management Tool (TAAMT) is a central database that contains all historical data and information for Metering System visits performed by TAA inspectors.

Use TAAMT to view inspection schedules, results, submit data and communicate with the TAA.

If you want to use this system, please contact the TAA Helpdesk to arrange an account. The TAA Helpdesk is available during business hours to answer questions and help with data submissions.

What do the TAA check during the Inspection Visit?

Whilst performing an audit, the TAA perform a series of checks to ensure the Metering Systems are compliant with the BSC and its Subsidiary Documents.

What happens after the Inspection Visit?

After the Inspection Visit, the TAA will show you the results and will share these with Elexon and the associated agents responsible for the Metering System.

You are required to rectify any non-compliance the TAA has identified.

The TAA publishes an Annual Report each year providing a summary of its findings. The Annual Report is presented to the BSC Panel in June each year.

Inspection Visit Health and Safety

Prior to attending site Inspection Visits, BSC Parties must update risk assessments and working practices to accommodate Covid-19 safety measures. The health and safety of attendees is the priority and Inspection Visits will not go ahead if attendees do not have the relevant risk assessments and working practices.

TAA Annual Report

The TAA Annual Report provides the Technical Assurance Agent’s view on the health of the Half Hourly metering population in the SVA and CVA markets. It is based on the findings from the inspection visits and is used to highlight key market issues, particularly those with high potential for materiality or risk to the quality of data used in Settlement.

The TAA’s report is divided into two parts:

  • Non–compliance statistics report
  • Commentary on the statistics

If you have had more than 25 TAA inspections during the audit period, you will receive your individual annual customer reports, and will also be offered a chance to discuss your individual findings with Elexon and the TAA.

We also produce individual confidential reports for Registrants (of Metering Systems) and Meter Operator Agents who receive 25 or more visits during the year.


The size and scope of the sample is set by the Performance Assurance Board (PAB) within the Risk Operating Plan (ROP).

For the audit year 2019/20, the PAB approved a 1% representative sample size for the SVA Metering System population and a 5% representative sample size for the CVA Metering System population.

In addition, the TAA will audit three Offshore wind farms in the 2019/20 audit year.

Technique within Performance Assurance process

Technical Assurance of Metering is a detective technique in Elexon’s Performance Assurance Framework. It provides a level of assurance that the metered values passed into Settlement represent actual consumption.

Non-compliances identified by the TAA assist with measuring the following Risks under the Performance Assurance Framework (PAF):

SVA Risks

  • 003 – SVA Metering Equipment is installed, programmed or maintained incorrectly including where Commissioning is performed incorrectly or not at all
  • 004 – Changes to SVA Metering Equipment are not notified, such that all members of the Supplier Hub do not use the current Meter Technical Details
  • 012 -SVA Metering System technical details are created incorrectly
  • 015 – SVA reference data is not created or transferred correctly, or at all

CVA Risks

  • 019 – A Volume Allocation Unit is registered incorrectly or not at all, such that the CDCA does not collect any or the relevant data
  • 020 – CVA Metering Equipment is installed, programmed or maintained incorrectly including where Commissioning is performed incorrectly or not at all
  • 022 – Changes to CVA Metering Equipment are not notified to CDCA
  • 024 – CVA Metering System technical details are created incorrectly
  • 026 – Aggregation Rules in CDCA are incorrect such that CVA Metered Data is not correctly aggregated and the energy volumes required for Settlement are incorrect or missing

BSC obligations

Elexon monitors the compliance of Metering Systems with the requirements stated in the BSC and Metering Codes of Practice (CoP).


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