A lock pin assembly is provided. The lock pin assembly is structured to coupled a panel board device to a panel board. The panel board device includes a body defining a number of mounting passages. The lock pin assembly includes an elongated body, a first radial extension, and, in an exemplary embodiment, a biasing device. The lock pin body is rotatably disposed in the panel board device mounting passage. The lock pin body is moved between an unlocked, first radial position, wherein said first radial extension does not engage a panel board back plate mounting tab, and a locked, second radial position, wherein said first radial extension engages a panel board back plate mounting tab.