IP68 16A 3-Way Weatherproof Junction Box - Clear Polycarbonate

The Knightsbridge JB004 is an IP68 rated 3-way junction box designed for permanent outdoor and underwater cable connections up to 16A at 450V. The clear polycarbonate housing contains a 3-terminal strip connector fixed inside, with three cable entry ports sealed by black threaded glands. Each gland accepts cable diameters from 5mm to 10mm, covering H07RNF 3-core flex from 0.75mm² to 4.0mm² cross-section.

Built for garden lighting circuits, pond pumps, outdoor security cameras and external sensors, the junction box provides a waterproof method of extending cable runs, repairing damaged outdoor cables, or splitting a power feed to multiple devices. The IP68 rating certifies submersion resistance to 2 bar pressure, making the box suitable for underwater installation in ponds, water features and irrigation systems as well as above-ground outdoor use. The polycarbonate housing resists UV degradation and impact damage better than standard ABS junction boxes.

The silicon sealing gasket between the lid and base compresses when the six Phillips-head screws are tightened, creating a continuous waterproof seal around the perimeter. Inside, the 3-terminal strip uses screw terminals to clamp each conductor, allowing cables to be connected and disconnected for maintenance without cutting. The clear housing allows visual inspection of connections without opening the box. The unit is certified to EN 50262 and rated T85 for ambient temperatures up to 85°C.

Product Specification Sheet

Product Manual

What does IP68 mean in practice?

IP68 certifies the junction box is dust-tight (the '6') and can withstand continuous submersion in water (the '8'). This specific box is rated to 2 bar pressure, equivalent to approximately 20 metres water depth, making it suitable for pond installations, underground cable runs and permanent outdoor exposure.

What cable sizes does it accept?

Each of the three cable glands accepts cables from 5mm to 10mm outer diameter. This covers H07RNF 3-core flexible cable from 0.75mm² to 4.0mm² cross-sectional area. Thinner or thicker cables will not seal properly in the glands.

Can the box be opened for maintenance?

Yes. The six Phillips-head screws securing the lid can be removed to access the terminal strip inside. When reassembling, ensure the silicon gasket sits cleanly in its channel and tighten all six screws evenly to maintain the IP68 seal.

Is it suitable for mains voltage outdoor lighting?

Yes. The 16A 450V rating covers standard 230V mains circuits. The junction box is commonly used for extending garden lighting runs, connecting outdoor sockets and linking security lighting to mains supply cables buried in garden borders.