Executive summary
Date(s) of inspection
- August 2026
Aim of inspection
This inspection was planned to gain assurance of the arrangements for installation and commissioning of HV switchgear. It aimed to gain assurance that priority actuation control system commissioning is adequate, and issues identified during manufacture are adequately resolved.
Subject(s) of inspection
- LC21 - Commissioning - Rating: Green
Key findings, inspector's opinions and reasons for judgement made
This Licence Condition 21 (Commissioning) compliance inspection was undertaken as part of ONR’s planned intervention programme at Hinkley Point C. The inspection was originally intended to sample High Voltage (HV) switchgear commissioning activities related to the LG system. As no HV commissioning activities were available during the inspection period, the intervention was refocused on the electrical commissioning arrangements supporting future HV commissioning activities.
The inspection focused on temporary modification control, configuration management, SQEP arrangements, commissioning issue management and observation of commissioning testing activities. The intervention also included a plant walkdown.
Overall, the activities sampled were being undertaken as described by NNB GenCo and in accordance with the arrangements reviewed during the inspection. I observed effective oversight of personnel competence and work allocation, robust temporary modification arrangements and strengthened configuration control through the use of dedicated configuration sheets within commissioning documentation.
I selected a temporary modification and traced it from the approved records through to physical implementation on plant. The walkdown confirmed alignment between the approved records, commissioning documentation and plant condition.
The inspection also identified several measures introduced by the electrical commissioning team to improve awareness of energised equipment and associated hazards. These included energisation status diagrams located at access points to switchgear areas and detailed visualisation tools developed to improve workforce understanding of energised cable routes. The visualisation tools had subsequently been shared more widely within the Commissioning Operations team for consideration and potential future application.
A small number of observations were raised relating to current injection testing documentation. These observations did not significantly affect the adequacy of the arrangements sampled.
Conclusion
Sampling of commissioning activities, competence and authorisation arrangements, temporary modifications and plant condition provided confidence that the electrical commissioning arrangements examined during the inspection were being implemented as intended.
I also observed measures introduced by the electrical commissioning team to improve awareness of energised equipment and associated hazards, including energisation status diagrams and three-dimensional cable route visualisations.
I identified a small number of opportunities for improvement during the inspection. These did not significantly affect the adequacy of the arrangements sampled.
On the basis of the evidence sampled, I judge that NNB GenCo has implemented adequate arrangements for the control of the electrical commissioning activities examined during this inspection and that these arrangements support compliance with LC21 (Commissioning).
Upon consideration of ONR guidance in relation to inspection ratings, I judge that a Green (No Formal Action) rating is appropriate.