A junction box – also known as an ‘electrical box’, ‘jbox’, ‘or ‘terminal box’ – is a protective box where wires are interconnected. Junction boxes are often built into the plaster of a wall, in the ceiling, or within concrete. They are standard within most homes, buildings, and factories.Junction boxes are found both indoors and outdoors. Waterproof junction boxes are commonly used outdoors.Junction boxes are typically made of metal or plastic. There 4 main electrical junction box types: Metal