Standard electrical box dimensions for European concealed wiring systems are typically 80mm in diameter and 55mm in depth, complying with EN 60670 standards to ensure compatibility and safe installation across EU countries. Do Standard Electrical Enclosure Sizes. Electrical control panels and distribution boxes are the backbone of modern electrical systems. From powering homes and industrial facilities to supporting medium-voltage infrastructure, these enclosures ensure safe, efficient, and reliable power distribution. Whether it's a small electrical. trial applications. Different incoming devices are available withi d outgoing devices.