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What is Joint Box
A junction box is an essential part of the electrical wiring systems for homes and commercial buildings. These metal or plastic boxes house and safely protect a structure's electrical connections. The electrical casings come in many sizes and types for various applications. National and local building codes necessitate the type of junction boxes needed for certain applications.
Benefits of Joint Box
Secure
Most weatherproof junction boxes are built from robust and sturdy material like stainless steel, thermoplastic, or ABS, and as such can withstand both high impacts as well as multiple challenging conditions. Due to their robust material composition, these boxes afford a decent security level; not just for safety but to also prevent unauthorized removal or tampering.
Durable
As previously mentioned, weatherproof electrical boxes are built using robust materials designed to work effectively no matter the weather conditions. Weatherproof junction boxes made of stainless steel assure resistance to various environmental concerns resulting in long and durable product life.
Shock Resistant
Depending on the material used to build a weatherproof electrical box, it can offer a degree of impact resistance. In particular, the high dimensional stability of polycarbonate enclosures allows these boxes to provide shock resistance.
Aesthetic Appeal
Polycarbonate weatherproof electrical boxes are remarkably appealing. While other materials such as fiberglass tend to create a surface degeneration which is noticeable in gloss and color loss due to prolonged exposure to UV rays, polycarbonate or aluminum materials retain their look. What's more, junction boxes made from stainless steel allow for great visibility that facilitates easy connections even in dark conditions.
Protect Against Extreme Weather Fluctuations
Sometimes when junction boxes are exposed to severe cold and hot weather or UV light, they tend to deteriorate and their ability to safeguard your electrical elements is compromised. Nonetheless, weatherproof junction boxes can effectively tackle this imminent weather threat since it features quality material designed to withstand extreme weather flux. These junction boxes are available in various robust materials including polycarbonate, aluminum, FRP (fiber reinforced polyester), and stainless steel.
Protect from Accidental Damage
Weatherproof junction boxes offer protection against accidental damage on the elements due to heat, loose connections, sparks, and short circuits. What's more, these boxes also conceal the cables, keeping them dust, dirt, and dampness free.
Types of Joint Box
Standard Residential Boxes
The most common junction box inside houses is the standard residential box. They're usually plastic enclosures with enough space to house plenty of residential wiring.
Round Junction Boxes
These metal boxes are standard in small residential and commercial spaces. They're strong enough to support up to 50 pounds, so they're good for supporting electrical appliances on ceilings or walls.
Outdoor Junction Boxes
These junction boxes have increased durability to withstand weather conditions and shield vulnerable wires from heat, rain, and vandalism.
Ceiling Junction Boxes
As the name suggests, ceiling junction boxes are for mounting on ceilings. They offer exceptional strength and durability, making them ideal for accommodating a lot of wiring in its interior and supporting anything that may hang from it.
Application of Joint Box
Office and Retail
Commercial office and retail buildings are typically the least demanding applications for junction boxes. However, these applications still need basic protection against unauthorized access and accidental contact, and they also usually need junction boxes with more space than you'll find in standard residential boxes.Sometimes, these applications don't require NEMA or IP enclosures. However, outdoor junction boxes might still be required in areas that will be exposed to adverse conditions. Specifying a junction box that slightly exceeds requirements can be a smart strategy for building resilience into a system.
Warehouses and Distribution Centers
Most warehouses and distribution centers aren't subject to harsh environmental conditions, but they're demanding applications nonetheless. These facilities often use a lot of electricity to power lighting systems, climate control and other essentials.Commercial enclosures for warehouses and DCs need an impact-resistant build, enough space to accommodate large numbers of connections and often a UL 94 flame rating. Logistics applications like these may also need outdoor junction boxes for loading docks and other partially exposed locations.
Marine Environments
Marine applications such as cargo ports, marinas or seafaring vessels are among the most demanding for any type of electrical component. Electrical connections in these areas have to withstand waves, wind, corrosive salt water and possibly even submersion.It's thus not surprising that these environments call for enclosures rated at the highest level of the NEMA and/or IP scales.
Manufacturing Facilities
The manufacturing industry requires extremely reliable and well-protected electrical systems. High voltage loads are often distributed through extremely complex systems across numerous branch circuits. Many manufacturing facilities also present hazards like flying debris and splashing water. All of these factors can add up to an extremely demanding set of conditions. enclosures are a good choice for less strenuous manufacturing environments. More hazardous environments, on the other hand, may need outdoor rated boxes like 3R enclosures or enclosures. Finally, manufacturing is another sector in which a UL 94 flame rating is often required.
Medical Facilities
Medical facilities also have large and complex electrical systems that require tough junction boxes. Reliability and ease of access are particularly important in medical applications, since an electrical failure can put lives in danger. Indoor junction boxes, such as , are common choices for medical facilities. However, many medical facilities are also part of large medical campuses with multi-building electrical systems. In such cases, outdoor rated enclosures (often buried underground) are an essential part of a safe and functional local power grid.
Essential Features for Junction Boxes
These two rating systems measure the protective qualities of electrical enclosures, including junction boxes. (Read our NEMA vs. IP guide to understand the differences!) Basically, these enclosure ratings allow you to choose an enclosure that offers the level of protection your wiring connections require.Check local commercial electrical codes to learn if you need to use junction boxes with a specific NEMA or IP rating. In most cases, the commercial electricians and engineers who are working on your electrical system will be able to point you to the right NEMA or IP rating as required by local codes.
By definition, junction boxes almost always require cutouts and/or knockouts in order to fulfill their function. Most junction boxes will need cutouts for cables and conduits to enter and leave the enclosure. However, this also means making sure that the enclosure maintains its NEMA or IP rating where the cables enter or exit.Polycase's custom CNC machining options make it easy to get the exact cutouts that you need on your commercial junction boxes. What's more, we offer several different models of cable glands for protecting cable entries into enclosures. For truly instant customization, we offer the SK Series, with built-in knockouts designed to fit standard cable sizes.
Junction boxes in commercial systems often need to be marked with identifiers or instructions. Technicians might need to know which specific connections a junction box houses or which boxes require extra safety precautions. For this reason, businesses may hire specialty printing companies to customize their junction boxes, or they may print labels and attach them in-house.
Some connection points need to be easily accessible to technicians for troubleshooting, especially junctions that supply power to critical system components. Enclosures with hinged covers make excellent junction boxes for these applications.Fortunately, Polycase's hinged enclosures give you these benefits without sacrificing security and protection. An enclosure with a hinged cover can still be waterproof and/or dustproof with the addition of a gasket seal on the door. For security, we include built-in lock hasps on our hinged enclosures to allow easy attachment of a padlock.
Sizes
The typical junction box size for residential use is a 4-inch square box, which is roomy enough for multiple wires and cables. Residential junction boxes come in other sizes, as well. These boxes are usually much smaller than a junction box used in a commercial setting which will have more connectors in one spot.
Materials
Junction boxes are made of either metal or plastic and each material has its pros and cons.Metal boxes are strong, and fireproof, and must be used with metallic-sheathed wire to provide proper grounding. They are a little more complex to work with because they have knock-outs for clamps and tricky sharp edges. Metal boxes can be recessed in walls and they are designed to mount heavy items.Plastic or PVC boxes can be used indoors with non-metallic wires but not with metal conduit since there is no grounding provided. They are not as strong and can melt in a fire, but they are less expensive than metal boxes, are lightweight, and have built-in clamps. Plastic cannot be recessed in walls.
Covers
All junction boxes must be covered, installed correctly, and in compliance with the applicable building codes. The cover protects the wires, keeps out dirt and dust, and prevents moisture from getting inside the box. The cover also prevents any sparks from igniting combustible materials should arcing occur due to a loose connection or short circuit.
Safety First
Always turn off the main power before working with a junction box. It can sometimes be a guessing game to figure out which breaker switch controls the room you're working on and often several different branch circuits feed through a single junction box. Turning off the home's power eliminates any confusion and removes the risk of a potentially fatal situation.
How To Wire a Junction Box?
Prepare the junction box
You need to choose the appropriate junction box based on your needs and mounting location. Now, ensure that it's securely fastened to a wall, ceiling, or other structure using the appropriate hardware.
Strip wires
The next step is to strip the insulation from the ends of the wires you plan to connect inside the junction box, typically about 1/2 inch to 3/4 inch.
Connect ground wires
If present, connect the green or bare copper ground wires together using a wire nut. Attach an additional ground wire if required by local codes.
Connect hot (black) wires
Now it's time to twist the exposed ends of the hot (black) wires together with a wire nut. Ensure a secure connection. If you have multiple wires to connect, use a pigtail (short wire) to connect them to the junction box's terminal.
Connect neutral (white) wires
Repeat the same process for the white neutral wires, connecting them securely with a wire nut.
Secure the wiring
Carefully fold the connected wires into the junction box and ensure there is enough space for them without overcrowding. Also, don't damage the wires during this process.
Install the junction box cover
Place the junction box cover over the open box and secure it using the provided screws.
Turn the power back on
Once the junction box is securely closed and the wires are safely enclosed, turn the power back on at the circuit breaker or fuse box.
Test the circuit
Use a circuit tester to verify that the circuit is functioning correctly.
Label the junction box. If necessary, label the junction box to identify the circuit or its purpose for future reference.
How to Maintain Joint Box
Inspect Annually
Junction boxes should be inspected at least once a year. Check for damage, loose connections, frayed wiring, corrosion, dirt buildup, and other safety issues. Address any problems immediately.
Keep Them Accessible
Junction boxes should not be hidden behind drywall, furniture, or insulation. Ensure they remain accessible for inspection and maintenance. Cover plates should be removable without tools.
Use Caution When Wet
If wetness penetrates a junction box, thoroughly dry the interior before restoring power. Employ a GFCI circuit breaker for added protection in damp locations. Never handle a wet junction box while energized.
Replace Damaged Parts
Replace any cracked, warped, or otherwise damaged box components. Use the matching size and type specified by the manufacturer. Upgrade to a weatherproof box in harsh environments.
Torque Connections
Check clamps and screw terminals periodically to ensure they are torqued to spec. Loose connections cause heat buildup. Use torque screwdrivers to avoid under/overtightening.
Add Extra Space
Crowded junction boxes should be replaced with a larger size to accommodate added wiring devices or conductors. This improves ventilation and reduces fire risks.
Our Factory
Shandong Haihong Power Equipment Co., Ltd. is located in wordwide cultural city - Qufu City,Shandong Province，China.Established in 2007.Our factory size is 20,000 square meters.it is specializing in the production of domestic ground beforehand with the optical fiber cable and line hardware production enterprise.Our production operation scope is involved in electric power,communication,railway,and many other fields.Through a modern scientific management,we have get a remarkable economic benefit.
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FAQ
As one of the most professional joint box manufacturers and suppliers in China, we're featured by quality products and competitive price. Please rest assured to wholesale high quality joint box in stock here from our factory.
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