This document provides specifications for various distribution boxes including dimensions, mounting sizes, and number of ways. Low-voltage fixed switchgear GGD series: Mainly used in power industries such as substations and power plants, with high breaking. Wiring diagram shows both PNP and NPN wiring. Actual units use PNP status indicator, NPN status indicator, or neither. Dimensions are shown in mm (in. 81 ft)]. Today, electrical systems are essential for homes and industries. SMART DISTRIBUTION BOXES FOR FLEXIBLE BUILDINGS. Fuses: Act as fail-safes, melting under excessive current to prevent damage.