PIN-BOARD TYPE MAIN DISTRIBUTION FRAME

PURPOSE:To reduce the occupying area of a main distribution frame (MDF) by coordinating a wiring function to connect the outside and the inside of a switching office at will while giving a safety function to the pin itself, and a safety function to protect the units in the container from the abnormal voltage and current. CONSTITUTION:In a pin-board 1 with contact points 2 at crossing points of X axes and Y axes, and in a pin-board type main distribution frame (MDF) to connect the inside and the outside of a switching office by inserting pins 3 at the contact points 2, the pins 3 have built-in protective elements against the overvoltage and overcurrent by themselves. The pins 3 with the safety function have triode lightning gas pipe GP between the grounding GND at the outside of the container OP as a protective element to an overvoltage, and two positive thermistors PTC between the outside OP and the terminals of the inside CO of the switching office. In such a composition, the occupying area of the MDF is reduced and the number of the connecting points is also reduced.