What is Junction Box

Generally speaking, the electrical junction box is a necessity for every modern electrical system. Commercial electrical systems, however, are frequently exposed to more demanding conditions than residential systems. Therefore, the junction box for a commercial is built for a stricter standard and equipped with commercial-grade features.
But what is a junction box for commercial use? And how can you find a junction box which aligns with the needs of your application? Luckily, today, we will discuss these in the following sections.

What is Junction Box?

An electrical junction box is an electrical enclosure that is designed to house one or more wiring connections. The enclosure could protect the connections and keep the vulnerable points such as wire splices, from environmental conditions and accidental contact.

Materials: Plastic VS Mteal Electrical Box

The electrical junction box can be made either of metal (usually aluminum or stainless steel) or plastic (usually polycarbonate or ABS). The material of the junction box requires different wires.

Therefore, the selection between metallic and plastic junction boxes is one of the essential decisions when specifying a junction enclosure type for a commercial application. Use the metal electrical box when metal-sheathed cable (also called armored BX cable) or metal conduit is running in or out of the box.

Also, the metal-sheathed cable and metal conduit usually need an electrical aluminum box or stainless steel electrical box. Plastic electrical enclosures are the standard choices for non-metallic wires. YONGU offers superior electrical aluminum box and customized aluminum box.

How to Get Right Size Junction Box

The size of the junction box is the second thing we need to take into consideration. The size of the enclosure determines the number of contained cables. In the previous posts, I illustrate this issue thoroughly, you could click this title to read:How to Size a Junction Box

Essential Features for Junction Box

Expect the material and size, there are others factors you should think about when selecting a junction box. The box features that we ’ll discuss below are also relevant in many different commercial applications.


Rating System: NEMA Rating or IP Rating

Both of these rating systems are used for measuring the protective qualities of electrical enclosures, including the junction box. They help you a lot in finding the right enclosure that offers the level of protection your wiring connections required. Before selecting the enclosure, you should check the local commercial electrical codes to learn whether you need to use an electrical junction box with a specific NEMA or IP rating.

Custom Cutouts/Knockouts

Because of the actual application, the junction always requires cutouts and/or knockouts to achieve the function. And, most junctions boxed will need cutouts for cables and conduits to enter and leave the enclosure. Meanwhile, it also means that the junction box should maintain the rating system where the cables enter or exit.
YONGU’s customization enclosure could fulfill the specific requirement, giving the perfect and right cutouts.


The junction box in the commercial systems often to be marked with identifiers or instructions to guide the technicians to know which specific connections a box houses or which boxes require extra safety precautions. For this reason, YONGU offers a silkscreen printing service for the customized enclosure, which could guide the technicians to make the right operation.

Surface Mounting Hardware

The junction boxes are usually mounted on walls or other flat surfaces, and you’ll need mounting hardware to attach the junction box securely. Mounting feet and flanges are some of the most common and practical ways to add mounting hardware to an electrical junction box. YONGU is professional enclosure manufacturer in China, you could contact us to find the best solution to get a great electrical box to mount on the wall.

The 3 Best Commercial Junction Boxes from YONGU

YONGU is one of the comprehensive and professional electronic enclosure manufacturers in China, and also a manufacturer of aluminum enclosure box. In this section, we’ll highlight some of our most popular electrical junction boxes

●Top1:This junction box is regarded as the best Industrial aluminum box which can be applied to many fields. First, the enclosure is composed of three parts: shell+ front/rear panels+ 8 crews, adopted the AL6063S materials.
Second, the internal card slot design is easy for PCB assembly installation. It is the perfect option for equipment for communication, medical, teaching experiment, environmental monitoring and testing, industrial control, rail transit, vehicle terminal, security and protection, electronics, instrument, and meter industrial.

●Top 2: This split aluminum enclosure is the classic one. Three colors are available in this enclosure: grey, blue, and silver. P.C.boards mount horizontally by sliding into internal slots extruded into the enclosure body. It is customizable in length, cutouts, milling, L shape, and panels.

●Top3: This 205x73.5mm H40 enclosure accepts OEM & ODM. It is one of the electronics component protection junction boxes can be DIY. One of the superiority is a two-piece body with an easily removable belly plate for easy access to the top interior of the enclosure. It is widely used in equipment for communication, medical, teaching experiment, environmental monitoring, and testing, industrial control, rail transit, vehicle terminal, security and protection, electronics, instrument, and meter industrial.


The junction box plays an important role in the electrical system in the modern-day. The junction box not only houses the important cables but also ensures the cables work normally. If you are finding the best electrical enclosure and components enclosure, you could get the perfect one from YONGU, an enclosure manufacturer specializing in split aluminum enclosures and plastic electrical enclosures.