CPV code 31230000 designates Parts of electricity distribution or control apparatus in the Common Procurement Vocabulary (CPV 2008), the EU classification used to describe the subject of public contracts.
31230000 is a leaf code — the most specific level of its branch — so it can be used directly as the main CPV code of a contract notice. If it does not quite fit, check the neighbouring codes under 31200000 (Electricity distribution and control apparatus).