a junction box assembly includes first and second structures , such as upper and lower cases . t - shaped aligning protrusions extend beyond an edge of a sidewall of the second structure and mate with a receiving member contained in the first structure . when the first structure is being aligned with the second structure , chamfers on the t - shaped aligning protrusion may be provided to help start the alignment process before the first and second structures are joined together . this allows for faster and easier assembly of the junction box and helps to reduce the mating forces between the first and second structures .