The maximum number of wires permitted in a junction box depends on the box size, wire gauge, and the number of devices (switches, receptacles) present; there is no single, fixed number. Think of a junction box as a safe haven for your electrical connections. It's essentially an enclosure, usually made of plastic or metal, where wires join together. Their main job? To protect those connections from the elements and, more importantly, from you accidentally touching them and getting. But there is a limit on how many wires in a junction box are acceptable. Most non-metallic boxes on the home stores will have a Cubic Inch per junction box printed in them. Many people miss these steps and face problems during.