When installing environmentally friendly flame-retardant cables, the determination of the bending radius needs to comprehensively consider the cable type, structure, material, and industry standards. The specific determination method is as follows:

1、 Determine the foundation coefficient based on cable type and structure

1. Unarmored cable
   ***Small bending radius ≥6 times the outer diameter of the cable.
   For example, for an unarmored cable with an outer diameter of 10mm, the bending radius must be ≥ 60mm.

2. Armored or copper tape shielded cable
   ***Small bending radius ≥12 times the outer diameter of the cable.
   For example, for armored cables with an outer diameter of 10mm, the bending radius must be ≥ 120mm.

3. flame retardant cable
   ***Small bending radius ≥8 times the outer diameter of the cable.
   On the basis of this standard, it is necessary to further verify whether the flexibility of environmentally friendly materials (such as low smoke and halogen-free sheaths) meets the standards for environmentally friendly flame-retardant cables.

4. Special material cable

• Fluoroplastic insulated and sheathed cables≥ 10 times the outer diameter.

• optical cableStatic ≥ 15 times outer diameter, dynamic ≥ 20 times outer diameter.

• Fieldbus communication cableSingle bending ≥ 10 times the outer diameter, continuous bending ≥ 20 times the outer diameter.

2、 Validate based on industry standards and regulations

1. ***Standard reference

• GB 50303-2002 "Code for Acceptance of Construction Quality of Building Electrical Engineering"：
  It is stipulated that the bending radius of the cable shall not be less than the diameter6-25 timesThe specific values need to be determined according to the product manual or regional standards.

• IEC standards：
  The International Electrotechnical Commission (IEC) also has clear requirements for the bending radius of different types of cables, which need to be cross validated with domestic standards.

2. Manufacturer Technical Parameters
   Environmentally friendly flame-retardant cables may experience changes in bending performance due to the use of special materials (such as low smoke halogen-free flame-retardant layers) or structures (such as reinforced armor). The small bending radius data provided by the manufacturer shall prevail, which is usually clearly indicated in the product manual or technical manual.

3、 Practical points for on-site installation

1. Avoid excessive bending

• A too small bending radius can cause damage to the internal structure of the cable, such as tensile deformation of the insulation layer, loose conductors, wrinkling of the metal shielding layer, etc., which can lead to a decrease in electrical performance or a risk of short circuit.

• Example: If the outer diameter of an environmentally friendly flame-retardant cable is 15mm, according to the standard of 8 times, the bending radius needs to be ≥ 120mm; if it is an armored structure, it needs to be ≥ 180mm.

2. Consider installation environment

• space constraintsWhen laying in narrow areas such as cable trenches and bridge bends, it is necessary to plan the path in advance to ensure that the bending radius meets the requirements.

• temperature effectHigh temperature environment may reduce cable flexibility, and it is necessary to increase the bending radius appropriately; In low-temperature environments, cables need to be preheated before bending.

3. Use professional tools to assist

• By using tools such as cable bending guide wheels and spring pipe benders, the bending angle can be controlled to avoid the radius being too small due to human operation.

4、 Supplementary explanation for special scenarios

1. Cable conduit laying
   If the cable needs to pass through a cable conduit, it is necessary to ensure that the conduit diameter is large enough to accommodate the shape of the cable after being bent with a small bending radius. Usually, the inner diameter of the cable conduit should be ≥ 1.5 times the outer diameter of the cable.

2. Parallel laying of multiple cables
   When multiple cables are bent in parallel, it is necessary to consider the mutual compression between adjacent cables. It is recommended to increase the bending radius appropriately (such as by 10% to 20%) to avoid local stress concentration.