Zhaga Book 18

Zhaga Book 18 is the specification behind the small round socket seen on modern European street lights, standardising the mechanical and electrical interface between a luminaire and a sensor or communication node. Its logic mirrors the NEMA socket but at smaller scale and lower voltage: the luminaire provides a sealed receptacle and DALI-based power/data lines, and any certified node — photocell, motion sensor, smart-city controller — twists on, IP-sealed, from any vendor. Book 18 nodes mount on top or underneath the fixture, and the D4i extension of DALI defines how the node reads energy data and diagnostics from the driver. For municipalities the point is vendor independence over a 25-year asset life: the luminaire, the node and the management software can each be replaced separately. Specifying “Zhaga Book 18 / D4i ready” costs little at purchase and keeps every smart-lighting option open.