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Securing Access for Technical Assurance Agent (TAA) Inspection Visits

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Securing Access for Technical Assurance Agent (TAA) Inspection Visits

Guidance Note


This guidance describes best practice for Half-Hourly Suppliers / Registrants and Meter Operators when arranging access and equipment needed to assist the TAA in performing inspections on Half Hourly (HH) Metering Systems.

What are TAA Inspection Visits?

The Technical Assurance of Metering technique is designed to assess the ‘health’ of the Half Hourly market by performing inspections on a proportional sample of Metering Systems and then extrapolating the findings to the whole of the market.

The TAA inspects 1% of the Supplier Volume Allocation (SVA) population and 5% of the Central Volume Allocation (CVA) population in every audit year.

The TAA requires a representative from the appointed Meter Operator Agent (MOA) to attend the planned inspection. The TAA may also require the Licensed Distribution System Operator (LDSO) to attend the planned inspection to provide access to Meter rooms and substations, under their control, and for Health and Safety reasons, e.g. to oversee work carried out near exposed Low Voltage (LV) and High Voltage (HV) conductors. These obligations are detailed in BSCP27.

BSCP27 states that the TAA should give a minimum of 20 Working Days' notice of an inspection to the Supplier / Registrant and the MOA, unless it is an urgent targeted visit directed by the Performance Assurance Board (PAB).

Metering Systems registered in a Licenced Distribution System Operator’s (LDSO) Supplier Meter Registration Service (SMRS) are known as SVA Metering Systems and Metering Systems registered in the Central Meter Registration Service (CMRS) are known as CVA Metering Systems.

The Balancing and Settlement Code obligates Suppliers to provide access to the site and Metering System.

Equipment requested on site

MOAs are requested to take their laptops out to Inspection Visits (where possible) to assist the TAA in identifying phase failures.

While on site the MOA should be able to identify when/if an alarm was flagged historically on the Metering System being inspected, and when/if a D00011 flow was sent as a result.

This will assist the TAA inspector with the accurate identification of non-compliances while on site.

Documentation to be provided to the TAA (where possible)

What is the impact of failing to secure access?

In 2017/18 the TAA could not access 10% of sites visited. This is estimated to have cost over £59,000 to the industry. We report the no access levels monthly, and both the Performance Assurance Board (PAB) and the BSC Panel have expressed concern about it, although they are pleased to have seen an improvement over the last seven years.

The level of no access for BSC Audit Year 2018/192 is currently 10% which is in line with previous audit years. The PAB is very keen to see the level of no access continue to fall so that the TAA can operate at its optimum level and so that you receive value for money. The following table shows the percentage of Inspection Visits which resulted in no access per audit year:

% No Access

BSC Year



























The cost of the TAA service is split proportionally across all signatories to the BSC, as with other services under the BSC. However, it is important to note that all MOA, LDSO or Supplier representatives required to accompany the TAA do so at their own cost. Ensuring that all actions have taken place to secure access will reduce costs or, at the very least, ensure that the cost is an effective one.

It is the responsibility of the Supplier / Registrant to ensure access is secured and also to make sure that the TAA is aware of any specific arrangements that are in place for a particular inspection. The Supplier / Registrant is usually able to do this because of the collaborative approach taken with the MOA, the LDSO and the TAA.

What is the main cause of failing to secure access?

78% of the instances of no access recorded in the 2016/17 audit period are as a result of closed / unoccupied sites and the customer being unable/ unavailable to provide access. These reasons can be mitigated by the Supplier / Registrant making sure that customers are available and know what is expected of them.

No Access Reason3

% of no access visits

Approx. Cost

Site visited customer unavailable to provide access



Site visited customer unable to provide access



Premises closed/unoccupied and no-one available to provide access.



Customer unable to find keys



MOA unable to secure access



Customer unwilling to provide access



MOA Representative did not attend



Unsafe access.


£ 700

MOP Representative did not attend


£ 700

Supply disconnected


£ 700

Other onsite


£ 700

There will always be isolated incidents of no access that may be due to weather conditions or the designated contact is unexpectedly absent on the day of the inspection. Many instances could be avoided with additional effort by the Supplier / Registrant to contact the customer and pass on detailed access information to the TAA. Contacting the head office for the customer informing them of a planned TAA inspection may not be sufficient – getting hold of a named contact at the site is more likely to lead to access to the Metering Equipment.

Special requirements to ask about include:

1.Is site unmanned?

2.Is the site seasonal (a school or a farm for example)?

3.Are there access or safety restrictions to the site / Meter?

4.Is a key required to access the Meter or other Metering Equipment e.g. any current and voltage transformers which provide measurement signals to the Meter

    1. These could be located in a locked substation either on or just off site?

    2. Who holds the key & will the key be available at the visit?

5.Is the Meter located in a hard to access place?


Key steps in securing site access (for Suppliers and MOAs)

1. Once the Supplier / Registrant has received notification of an impending inspection visit, they should call the customer to arrange access to the site.

    1. They should ask about all special requirements for the site and request contact details of a named individual who will be on site at the time of the inspection and can assist in securing access to the Metering Equipment.

    2. If a site is suspected to be closed or unoccupied (e.g. there has been no successful contact with the customer), they should work with the DC to look at the level of consumption for the site and see how that fits with expectations.

    3. If a site is proven to be closed or unoccupied and taking very little or no energy, then this may be grounds for removal of this site from the sample and inclusion of another in its place. The Supplier / Registrant will firstly need to liaise with the DC, and then with the TAA to discuss/arrange this.

2. Once the MOA has received notification of an impending inspection visit, they should ensure that all data and information is available necessary to be able to access the property, the Metering System and ALL Metering Equipment. They should liaise with the Supplier / Registrant as necessary to arrange access.

3. Once the DC has received notification of an impending inspection visit, they should ensure that they has all data and information available to provide to the TAA. They should also check consumption values over the last 12 months to check for signs that the customer is no longer there or if there is little or no energy being measured. They should ensure that this information is passed to the Supplier / Registrant and included in the data passed to the TAA.

4. The Supplier / Registrant should also liaise with the MOA (and LDSO if necessary) to confirm attendance and share customer contact details and special site requirements. The Supplier / Registrant should make sure that the MOA is already aware of the impending inspection and should support the MOA as necessary in working with the TAA.

5. It may be necessary at this point for the Supplier / Registrant to liaise with the TAA because they may need to reschedule the visit (e.g. the site is seasonal or unmanned and further notice for the customer may be required).

6. The Supplier / Registrant should update the TAA with any special requirements (via the TAAMT, preferably) and provide contact details for the named individual in step 1.

7. Once the Supplier / Registrant has secured access, they should send a follow up letter to the customer confirming the arrangements for the visit. It may be helpful to use the wording in the sample letter shown below.

8. If the customer cannot be reached by phone, the Supplier / Registrant should advise the TAA and the MOA that visit details have been forwarded but not confirmed by the customer.

9. In all scenarios the Supplier / Registrant should update the TAA/customer/MOA of any changes in arrangements prior to the site visit.

If you have questions or comments about this guidance or any area of Technical Assurance of Metering, please contact us:

Sample Letter

Customer Address

Customer Address

Customer Address

Customer Address


Inspection Visit Reference: YYYY-XXXX

Technical Assurance Inspection of Electricity Metering System for MPAN ID: 1234567891234

Dear Sir/Madam,

Further to our telephone conversation, the Technical Assurance Agent (TAA) will be coming to inspect the electricity metering system at your premises. The TAA is an agent under the Balancing and Settlement Code (BSC), which is administered by Elexon Ltd.

All electricity suppliers must sign up to and adhere to the BSC. It is part of the industry governance arrangements managed by Ofgem – Office of the Gas and Electricity Markets.

The BSC allocates energy used by you to your electricity supplier. The BSC requires that these meters are inspected to check they are accurate. This is done using the TAA who inspects a sample of meters each year.

Your metering system is going to be inspected. The TAA will visit the site, with a representative from your meter operator, to perform the inspection. The results are used to detect any problems with the way in which the meter is set up or is recording energy used. Any problems found will be rectified through your electricity supplier.

The TAA and your meter operator will be visiting your premises [week commencing DD- MMM-YYYY or SPECIFIC DATE DD-MMM-YYYY].

Please can you ensure that there is safe access to the site and that relevant personnel and keys (if required) are available to access the electricity metering system.

There will be no interruption to your supply and there will be no charges incurred to you for this inspection.

If the date & time is not convenient or you require further information regarding Elexon Ltd, the TAA or the work being carried out, please do not hesitate to contact us and we will be happy to discuss this with you.

Thank you for your co-operation in this matter.

Yours faithfully

Need more information?

For more information please contact the BSC Service Desk or call 0370 010 6950.

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If you have questions or comments about this guidance or any area of Technical Assurance of Metering, please contact:

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1 Fault investigation flow

2 Year to 08 November 2017.

3 Year to date no access up to 13 November 2017