A comprehensive review of the precautions for the use and installation of fire-resistant bridges!

Traffic bridges are ubiquitous in our daily lives. They not only protect cables and wires from external factors but also ensure electrical safety. There are many types of cable bridges, one of which is fire-resistant cable bridges. Today, we'll discuss the precautions for using and installing fire-resistant cable bridges.

What precautions should be taken when installing fire-resistant cable bridges? Let's take a brief look.

All non-conductive iron parts of the cable bridge should be connected and bridged to form a continuous conductor and grounded as a whole. Braided copper wire should be used as the grounding jumper between each bridge. When installing fire-resistant cable bridge horizontally, the support span is generally 1.5-3 meters. When installed vertically, the distance from the fixed point should not exceed 2 meters. The cable bridge should be straight, free of distortion, and free of burrs on the inner wall. All accessories should be complete. The cable bridge joints should be straight, and the seams should be tight and straight. After installation, the cover plate should be flat, without corners, and the air outlet should be facing correctly. When installing within a suspended ceiling, an inspection hole should be left if the ceiling cannot reach this area. When a bridge passes through a building's expansion joint, the bridge itself should be disconnected, and the slots should be bridged with connecting plates, not fixed. Allowances should be left for the protective ground wire and the conductors in the slot. For straight steel bridges, strict construction regulations and systems should be followed, construction personnel management should be strengthened, technical measures for fire-resistant bridge construction should be implemented, and safety measures should be inspected and supervised for safe operation, ensuring civilized construction.

Construction personnel should be trained in construction standards and understand construction drawings. Construction should be carried out strictly in accordance with the plan and relevant specifications, procedures, and standards. Construction quality should be inspected regularly, and any problems identified should be promptly corrected. Scaffolding, parallel erection systems, electromechanical equipment, and safety devices used at fire-resistant bridge construction sites must comply with relevant regulations and must pass inspection before use.

What are the precautions for using fire-resistant bridges? Let's take a brief look.

1. Cables and wires should not be placed in the same slot. Reason: The permissible temperatures of the two types of wires are different. The thin insulation layer of the wires is easily pulled by the cables, and the mechanical strength of the wires is insufficient, making them prone to breakage.

2. Designers should familiarize themselves with the specifications and ensure that the volume occupied by the cables meets the requirements, generally 40%. Try not to exceed the specified density to avoid accelerating cable insulation aging, which will require larger cables and increased investment.

3. The cable capacity of a cable tray should be considered based on the number of cables in the tray and the ambient temperature. Generally, it should be 60%-80% of the rated cable capacity. Plastic trays, due to poor heat dissipation, should be 50%-70%.

4. Cables of different types should not be laid in the same tray, primarily due to different operating temperatures. For example, the VV series is rated for 65°C, while the YJY series is rated for 90°C. If laid in the same tray, low-temperature-resistant cables will experience accelerated insulation aging.

5. Due to its unique structure (internal fireproofing with fireproof cotton and fireproof panels), the internal space of a fireproof cable tray is smaller than that of a standard cable tray. When selecting, pay attention to the cable volume ratio. 6. Due to its unique structure (internal fireproofing cotton and fireproof panels), fire-rated bridges are heavier than ordinary bridges. When designing fixed supports and hangers, the standard spacing specified in the steel bridge design specifications cannot be used. Instead, the spacing should be increased. A spacing of 1-1.5m is recommended, depending on the size of the designed fire-rated bridge.

7. Due to the unique structure of ventilation duct fire-rated bridges (internal fireproofing cotton and fireproof panels), heat dissipation conditions are poor. Therefore, the cable current carrying capacity should be 40%-60% of the rated current carrying capacity of the cable.