Devonport Dockyard — Site-Wide Earthing Survey
Site wide earthing survey of an active naval dockyard
The challenge
Devonport is the largest naval base in Western Europe, and the electrical estate reflects more than 50 years of organic growth across multiple voltage levels and two frequencies. There was no single earthing design to measure the survey against, so each substation had to be assessed on its own merits, while also considering how the network as a whole was bonded together and where transfer voltages could flow between systems.
What Aurora did
We carried out a site-wide survey covering the 33 kV, 11 kV (50 Hz) and 6.6 kV (60 Hz) systems, taking in more than a hundred substations from modern installations through to assets several decades old. The survey identified high-risk areas requiring immediate remedial action and set out a longer-term route to a Global Earthing System (GES) classification for the site. The deliverable was as much a strategy document as a set of calculations, because the ongoing programme of work mattered more than any single number.