The waterproof performance of the terminal box

Core concept: Protection level (IP code)

The waterproof capability is usually indicated by the IP (Ingress Protection) protection level, followed by two digits:

The first digit (0-6): Rating for preventing solid foreign objects (such as dust).

The second digit (0-9): Water resistance rating. This number directly indicates the strength of the waterproofing performance.

Common waterproofing grade explanations:

IP65: Completely dust-proof and capable of resisting low-pressure water jets from all directions. This is a common standard for outdoor applications and can withstand rainwater splashes.

IP66: Completely dust-proof, and can also prevent powerful water jets from all directions (such as waves, strong splashes).

IP67: Completely dust-proof, and capable of being briefly submerged in water (typically meaning immersion in water up to 1 meter deep for 30 minutes).

IP68: Completely dust-proof, and capable of being continuously submerged in water to a certain depth (the specific depth and duration are specified by the manufacturer). Suitable for long-term underwater environments.

The key design and technology for achieving waterproof functionality

Sealing ring (Gasket)

This is the most crucial component. Between the lid and the body of the box, there is a high-quality silicone or rubber gasket. When the screws are tightened, the gasket will be uniformly compressed, forming a waterproof barrier.

Waterproof cable connector (Cable Gland)

The inlet of the terminal box uses waterproof cable connectors. They usually have threads and sealing rings. After being tightened, they can tightly enclose the outer sheath of the cable to prevent water from seeping in through the cable inlet.

Box material

Waterproof terminal boxes are usually made of materials that are resistant to corrosion and weathering, such as high-quality engineering plastics (PP, PC) or stainless steel (SS304, SS316), to ensure that the enclosure itself does not rust or degrade in a humid environment.

Integrated design or glue application

Integrated Injection Molding: For products with high protection requirements, the box body adopts a seamless integrated design, fundamentally eliminating the possibility of water seepage.

Gel-filled junction box: After the wiring is completed, epoxy resin or polyurethane waterproof glue is injected into the box. After the glue cures, it can completely seal all the wire ends and terminals, achieving an extremely high level of waterproof and moisture-proof performance (usually up to IP68), and even resistant to acid and alkali corrosion. It is commonly used in underwater lights, photovoltaic power stations and other extreme environments.

Application scenario suggestion:

IP20/IP40: Only applicable to dry and clean indoor environments (such as inside control cabinets).

IP65/IP66: Suitable for outdoor use, car wash areas, food and beverage industries (frequent rinsing), and humid industrial environments. This is the most common choice.

IP67/IP68: Suitable for scenarios where there is a possibility of water immersion or where equipment needs to work underwater for an extended period, such as manholes, underwater equipment, docks, sewage treatment plants, etc.

Important Note:

Proper Installation: Even if you purchase a high IP-rated junction box, if the installation is incorrect (such as the sealing ring not being tightened properly, the cable connector not being tightened, or the wrong specification being chosen), the waterproof function will fail.

Regular maintenance: After long-term use, the sealing ring may age and crack. It is necessary to conduct regular inspections and replacements to ensure the protective performance.

In summary, the terminal box indicates its waterproofing capability through the IP rating, and achieves protection through designs such as sealing rings and waterproof connectors. Choosing the appropriate IP rating based on the actual application environment and correctly installing it are the key to ensuring the safe and stable operation of the circuit.