Common Problems with Junction Boxes & How to Fix Them

Junction boxes: Provide a safe "home" for the secure connection of electrical protection.

As an expert in the field of high-protection electrical engineering, this blog will introduce the problems of junction boxes and their solutions based on extensive factual evidence, providing valuable help for your daily selection and use.

Composition of Junction Boxes

Mainly consist of an outer casing, a casing cover, and a sealing ring.

They are equipped with cable entry/exit holes / cable glands, as well as screws, mounting lugs, hanging feet, and DIN rail buckles. Inside the casing, there are terminal blocks, fixing bases, grounding terminals and brackets.

These components mainly help with waterproofing and fixing of the outer casing, laying a solid foundation for building a stable and safe electrical system.

Sealing Problems

In addition to the inherent waterproof performance of junction boxes from the factory, their sealing is also greatly related to the edges of the openings and contact parts. There is usually a sealing ring inside the casing to assist with edge sealing, and the tightness of the connection between cable glands / cable connectors and the edges of the outer casing is also critical.

Structural and Material Problems

Poor-quality plastic materials lack impact resistance, corrosion resistance and high-temperature resistance, resulting in severe cracking of the outer casing.

There are usually two options for bolts: metal bolts and plastic bolts. Selecting inappropriate materials will lead to rusting in humid environments and poor smoothness in high-intensity operations.

Loose-fitting covers with warped edges are most likely caused by poor mold precision and deviations in buckle holes.

Insufficient cover strength cannot withstand high-intensity impacts, resulting in damage to components inside the casing.

Electrical Safety Problems

Internal terminals, casing or partitions, grounding terminals and flame retardant ratings.

This is usually caused by loose crimping of terminal wires and poor contact leading to heat generation, which causes the circuit to contact the outer casing and generate heat. In this case, the flame retardant rating of the casing must meet the standard to withstand the generated temperature. Grounding terminals can prevent electric shock when personnel inspect without safety measures, playing a protective role. Therefore, careful selection is essential for safety.

Installation and Adaptation Problems

Before selecting a suitable junction box, first confirm whether the dimensions on the drawings match your project.

Check if the mounting hole spacing is compatible without deviations, the number of inlets, the suitability of hole positions, and whether the internal space can accommodate sufficient cables.

Environmental Adaptation Problems

Select according to the environment: weather resistance, corrosion resistance and high-temperature resistance are three essential requirements.

Certification and Compliance Problems

CE, RoHS, IP testing are mandatory for export customs clearance and reporting.

How to Solve These Problems? --- Let Me Tell You How to Choose

High-quality sealing materials must be weather-resistant silicone rubber and EPDM (Ethylene Propylene Diene Monomer), which feature strong weather resistance, excellent anti-aging sealing performance, ideal for making sealing rings, with great resilience and not easy to fail in long-term outdoor use.

*EPDM: Can be used for a long time at -40℃～120℃, suitable for high-quality weather-resistant silicone rubber. The material itself is relatively saturated with a very stable chemical structure, not easily damaged by sunlight, ultraviolet rays, ozone and moisture, and has excellent stress resilience. (Full molecular structure, uniform cross-linking, strong elastic framework, saturated structure)

Material Safety Selection

Must choose brand-new PC/ABS/nylon engineering plastic raw materials, reject recycled materials and inferior fillers, to ensure the toughness and impact resistance of the material.

Select bolts with galvanized / nickel-plated anti-rust treatment.

Solution to Insufficient Strength

Strictly select mature and stable injection molding technology, and the strength of one-piece injection molded products must meet the standard before leaving the factory.

*Brand-new PC/ABS/nylon engineering plastics have high purity and uniform strength, and UV stabilizers can be added normally.

*Galvanized and nickel-plated bolts form a protective film on the surface, preventing rust from the root cause.

*Uniform wall thickness + formal technology ensure high strength. We understand the problem of stress points: when a single stress point is compressed, sufficient edge wall thickness can disperse the force evenly, avoiding single-point cracking.

Conclusion

The difference between choosing good materials and inferior materials is never a slight difference in cost, but a vast disparity in the safety risks of electrical systems.

CNPNJI, with 18 years of experience in manufacturing high-protection electrical equipment, has always used brand-new engineering plastics to create high-quality products, eliminating hidden dangers from the source and providing a real home for electrical safety.