Requirements for incoming and outgoing lines of explosion-proof distribution boxes

Explosion-proof distribution boxes require bottom-positioned inlet and outlet ports, explosion-proof steel pipe or cable wiring, proper sealing, and compliance with IECEx, ATEX, and national standards.

Wiring Methods

Incoming and outgoing lines in explosion-proof distribution boxes typically use explosion-proof steel pipes or cables. Thick-walled pipes are preferred, and some installations may require pressure testing to ensure integrity. For cable wiring, overhead lines of 10 kV and below should not cross hazardous areas, and if adjacent, the distance must be at least 1.

5 times the tower height to prevent accidental ignition.

Inlet and Outlet Line Positioning

The inlet and outlet ports should be located on the lower bottom surface of the box. Avoid positioning on the top, sides, back, or door. Special designs (e.g., top-in/top-out or top-in/bottom-out) require enhanced sealing, including regular inspection, tightening of compression nuts, and secondary sealing with explosion-proof cement.

Wire Selection

Choose wires according to the rated current, environmental conditions, and safety factors. The conductor's allowable current must be at least 1. 25 times the rated current of the fuse or circuit breaker.

In hazard level 2 zones, power lines should use aluminum core wires ≥4 mm², and lighting lines ≥2. 5 mm². In hazard level 1 zones, copper core wires or cables are required.

All cables must pass through rubber sealing rings and be compressed with washers and nuts to ensure flameproof sealing. Loose cables are prohibited, and unused ports must be sealed with gaskets and metal covers.

Marking and Protection

Wires should be clearly marked for easy maintenance and repair. Power cords must not be connected via plugs. Inlet and outlet cables should be sheathed, bundled, and waterproofed, avoiding direct contact with the box openings.

Compliance with StandardsExplosion-proof distribution boxes must comply with IECEx, ATEX, and national standards such as IEC 60079 series. These standards define equipment protection levels (EPL), zone classifications, and flameproof construction requirements. Proper certification ensures safe operation in Zones 1, 2, 21, 22 or Class I/II Division 1 hazardous areas.

Summary

To ensure safety and compliance: Use explosion-proof steel pipes or cables. Position inlet/outlet ports at the bottom. Ensure proper sealing and compression.

Select wires according to current rating and hazard level.

Follow IEC

Ex, ATEX, and local regulations for installation and maintenance. These measures prevent ignition of explosive atmospheres while maintaining reliable operation in hazardous environments.