An electrical connection box for wall mounting provides a recessed external plug for receiving or transmitting power to electronic components. The clearance space of a direction of a second axis perpendicular to the first axis is dimensioned to be greater than the clearance space of a direction of the first axis. The unit grid straps form a grid structure that have inner grid holes into which the dual-cooled fuel rods are held, and the held dual-cooled fuel rods are each supported in four directions by the upper and lower dimples. The optical bypass circuit transports traffic that originates at the node plus transient traffic that the node receives from other nodes.