What Is a Junction Box?

Whether there is an electrical circuit present in a home, commercial building, or an aircraft, it is very important to implement organizational tools and equipment to ensure that circuits and other electrical components are well managed. An electrical junction box is the solution for such needs, and they come in the form of enclosures that may be used to house various electrical connections. Beyond serving organizational needs, a junction box may also be used to protect electrical connections from weather and may guard individuals from shock.

For the construction of a junction box, metal or plastic may be used, though stainless steel is the most beneficial for high-temperature applications or when fireproofing is necessary. Junction boxes also commonly serve as a part of an electrical conduit or thermoplastic-sheathed cable wiring system, and they are commonly mounted to the framing of a building, placed in a floor or ceiling, or contained within an access panel. When junction boxes, electrical conduit components, and other parts are replaced, it is important that the same materials are used for fabrication to ensure proper protection and functionality.

When designing a junction box or deciding between options, it is important that the construction permits easy access to terminals, wires, and other installed items. It is also important that there is proper grounding and insulation for the junction box, as any overload conditions or surges need to be mitigated so that they cannot destroy sensitive electronic equipment. For the ease of proper circuit management and inspections, never mount any wires or components to the access door of the box, otherwise it will be very difficult to determine proper clearances while the door is shut.

When a junction box is used for aircraft parts and electrical circuits, they should be mounted to the structure of the aircraft in a way that permits easy access and inspection. It can actually be useful to have the opening either face downwards or at an angle, thus ensuring that any loose fasteners or aircraft parts fall out of the assembly instead of becoming caught between terminals. As aircraft systems are best designed with possible future installations in mind, the junction box or electrical conduit assembly should have ample space for wires or aircraft parts that may be added later. With the use of lacing or clamping, wire bundles can safely be separated from one another.

For buildings, junction boxes and electrical conduit assemblies may be required by electric code for any wire splice. Wire splices can be dangerous if unprotected or unmanaged, often presenting the possibility of sparks and shock which can be dangerous for surrounding individuals and flammable materials. As such, it is important to ensure that no wire splices are missed and that all are safely contained within a junction box. Splices are useful for joining together conductors when new terminations are needed, thus storing them in a junction box can make finding them easier when the time comes.

With the use of junction boxes, electrical conduit equipment, thermoplastic-sheathed cable wiring systems, and other such devices, the electrical circuits and components of a building, home, or aircraft may be protected. Aerospace Store is a trusted distributor of aircraft parts and electronic equipment, and we are your one-stop-shop for all the junction box components that you need for your circuit management endeavors. As the only independent distributor with a strict no China sourcing pledge, we choose to only work with top global manufacturers that we trust. To begin the part procurement process for parts that you are interested in, fill out and submit an Instant RFQ form as provided on our website and a dedicated account manager will reach out to you in 15 minutes or less with a personalized quote for your comparisons.


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