This is an example of why it is very important to have the electrical panel boxes inspected closely as apart of a home inspection. During this inspection which occurred in Parker Colorado, I checked this sub-panel located in an out building. The image on the right is the panel with the cover on, and the image on the left is with the cover off. As you can see, the panel looks OK from the outside and the dead front (panel cover) is clean, although it was apparent that the cover screws were not correct and were not installed tightly. When the cover was removed, I discovered that the interior was rusty in places, indicating moisture may have gotten into the panel. This can present a serious safety concern. In addition, holes in the panel box allowed insects to build a hive on the neutral wiring inside. Lastly, the neutral bus bar on the right, (which is the one with the white colored wires attached) was not bonded to the ground wiring (the copper wires) which are in the system to transfer current safely to the grounding rod outside in the event of a lightening strike or system malfunction. In this case, it was important that the client make sure to have this sub panel corrected by a qualified electrical contractor.