PURPOSE: A distribution board with a color steel sheet is provided to reduce vibration and noises by compactly combining an external box base and a door with the color steel sheet. CONSTITUTION: An AISS switches an extra high voltage lead-in line. A branch switch block is installed in a low voltage chamber of an external box base. A door(130) is laminated on a steel sheet. A lateral side is formed by laminating the steel sheet and sound absorbing materials.
