Fundamental Distinction: Terminal boxes utilize structured terminal blocks for organized, accessible connections and frequent maintenance, whereas junction boxes protect permanent wire splices and are rarely accessed after installation. They are not like software terminals such as Mac Terminal or command line interfaces. Choosing the proper terminal installation location. There is a 10-2 (w/ground) UF cable which runs from my main panel in the basement, through the joists in the crawlspace, and exits the house here: Here's the outdoors side, where it connects to the disconnect (which is right out of view at the top of the picture): It doesn't look like whoever did. These are boxes that house insulated terminal blocks that are used in joining two or more wires. Their main application is in factories with the main purpose of having all wires secured and terminated. Pull boxes, junction boxes, and conduit bodies must be sized to allow conductors 4 AWG and larger to be installed without damage to the conductor insulation. The NEC provides sizing requirements in 314. Keep in mind these. To install a junction box correctly, choose a box that matches the wiring method and environment, mount it securely, bring cables in with the right fittings or clamps, make proper splices inside the box, and close it with an accessible cover.