Introduction 引言

The proper selection and installation of cable grips, particularly Kellem grips (also known as mesh grips or wire mesh grips), is critical for ensuring safe vertical suspension of heavy-duty cables in industrial environments. This is especially important for (N)SHTÖU cables, which are specifically designed for reeling applications in demanding conditions such as mining operations, port container handling equipment, and mobile industrial machinery. 正确选择和安装电缆夹具，特别是Kellem网套（也称为网状夹具或金属丝网夹具），对于确保工业环境中重型电缆的安全垂直悬挂至关重要。这对于(N)SHTÖU电缆尤其重要，这些电缆专为采矿作业、港口集装箱处理设备和移动工业机械等苛刻条件下的卷筒应用而设计。

Kellem grips were originally developed by Hubbell Wiring Device-Kellems and have become the industry standard for cable pulling and support applications worldwide. These wire mesh devices provide uniform compression over the cable surface, preventing damage while maintaining secure holding power under heavy loads and continuous stress conditions.

Source: Hubbell Wiring Device-Kellems Wire Management Solutions

Understanding (N)SHTÖU Cable Specifications (N)SHTÖU电缆规格说明

(N)SHTÖU cables (also written as NSHTOEU or NSHTOU) are heavy-duty rubber-insulated flexible reeling cables designed according to German standards DIN VDE 0250 Part 814 and HD 308 S2. These cables are specifically engineered for applications involving very high mechanical stresses, including simultaneous tensile and torsional forces. (N)SHTÖU电缆（也写作NSHTOEU或NSHTOU）是根据德国标准DIN VDE 0250第814部分和HD 308 S2设计的重型橡胶绝缘柔性卷筒电缆。这些电缆专门设计用于涉及极高机械应力的应用，包括同时承受拉伸和扭转力。

Technical Characteristics 技术特性

Sources: Eland Cables – NSHTÖU Cable Specifications, Tampereen Sähköpalvelu – Drum Cable NSHTÖU-J Technical Data

Vertical Reeling Variant: (N)SHTÖU-V 垂直卷筒变型：(N)SHTÖU-V

For vertical reeling operations and spreader applications, the (N)SHTÖU-V variant is specifically designed to handle the extreme stresses encountered in vertical suspension systems. This cable type features enhanced construction with reinforced strain relief elements to support its own weight over extended vertical distances. 对于垂直卷筒操作和吊具应用，(N)SHTÖU-V变型专门设计用于处理垂直悬挂系统中遇到的极端应力。该电缆类型具有增强的结构，配有加强的应变消除元件，以支撑其在延伸垂直距离上的自重。

Source: Hybird Resources – Vertical Reeling Cable (N)SHTOEU-V Technical Information

Cable Grip Types and Functions 电缆夹具类型和功能

Support Grips vs. Pulling Grips 支撑夹具与牵引夹具

It is essential to distinguish between two fundamental categories of cable grips when planning vertical suspension systems:

Support Grips (Strain Relief Grips): These wire mesh devices are specifically designed to hold the weight of suspended cables in vertical runs and prevent strain, pullout, and damage caused by vibration, flexing, or movement. Support grips distribute compressive force uniformly over a large area of the cable jacket, ensuring continuous cable support without damaging the insulation or conductor. 支撑夹具（应变消除夹具）：这些金属丝网装置专门设计用于在垂直走线中承载悬挂电缆的重量，并防止因振动、弯曲或移动引起的应变、拉出和损坏。

Pulling Grips: These are temporary installation tools used to pull cables through conduits, trenches, or cable trays during installation. While pulling grips use similar mesh construction, they are not designed for permanent vertical weight support. Using pulling grips for long-term vertical suspension applications is a serious code violation and safety hazard. 牵引夹具：这些是临时安装工具，用于在安装期间通过管道、沟槽或电缆桥架拉动电缆。虽然牵引夹具使用类似的网状结构，但它们不是为永久垂直重量支撑而设计的。

Sources: Hubbell – Cable Strain Relief Grips, GlobalSpec – Pulling and Support Grips Selection Guide

Selection Criteria for Cable Grips 电缆夹具选择标准

1. Cable Diameter Range 电缆直径范围

Each Kellem grip is manufactured for a specific cable diameter range, typically spanning approximately 0.5 inches (12-13 mm) within each size designation. The grip must match the actual outer diameter of the installed cable, including all jackets and sheathing. Using an incorrectly sized grip will result in either insufficient holding power (too large) or potential cable damage (too small). 每个Kellem夹具都是为特定的电缆直径范围制造的，每个尺寸代号通常跨越约0.5英寸（12-13毫米）。夹具必须与安装电缆的实际外径匹配，包括所有护套。

For (N)SHTÖU cables, common outer diameters range from approximately 15 mm (for 4-core 1.5 mm²) up to 80 mm or more (for 45-core 16 mm² configurations). Always measure the actual cable outer diameter and select grips accordingly.

2. Breaking Strength and Working Load Limits 断裂强度和工作负荷极限

Cable grips are rated by their minimum breaking strength, which represents the load at which failure occurs under test conditions. However, the critical specification for installation planning is the Working Load Limit (WLL), which is typically 20% of the breaking strength, providing a 5:1 safety factor in accordance with industry standards. 电缆夹具按其最小断裂强度额定，这代表在测试条件下发生故障的载荷。然而，安装规划的关键规格是工作负荷极限（WLL），通常为断裂强度的20%，根据行业标准提供5:1的安全系数。

Sources: Grainger Canada – Kellems Cable Support Grip Specifications, Griplock Systems – Weight Load Guidelines

3. Cable Weight Calculation 电缆重量计算

To properly select cable grips, you must calculate the total suspended weight. This includes:

• Cable weight per meter multiplied by total vertical distance 电缆每米重量乘以总垂直距离
• Safety factor for dynamic loads (typically 1.5x for moving applications) 动态载荷的安全系数（移动应用通常为1.5倍）
• Additional weight from cable movement or ice/environmental accumulation 电缆移动或冰/环境积聚的额外重量

Example calculation for a 50-meter vertical run of (N)SHTÖU-J 18G2.5 cable:

4. Material Selection 材料选择

Kellem grips are available in different materials to suit various environmental conditions:

• Galvanized Steel: Standard choice for most indoor and general outdoor applications 镀锌钢：大多数室内和一般室外应用的标准选择
• Stainless Steel: Required for corrosive environments, marine applications, and chemical processing facilities 不锈钢：腐蚀性环境、海洋应用和化学加工设施所需
• Tin-Coated Bronze: Premium option providing excellent corrosion resistance and conductivity 镀锡青铜：提供出色的耐腐蚀性和导电性的高级选项

Source: Graybar – Kellems Strain Relief Cable Grip Material Options

Installation Standards and Requirements 安装标准和要求

NEC Article 300.19 – Supporting Conductors in Vertical Raceways NEC第300.19条 – 垂直线槽中的导体支撑

The National Electrical Code (NEC) provides specific requirements for vertical cable support. Article 300.19(A) mandates that one cable support shall be provided at the top of vertical raceways or as close to the top as practical, with intermediate supports installed at intervals determined by the conductor size. 美国电气规范（NEC）为垂直电缆支撑提供了具体要求。第300.19(A)条规定，应在垂直线槽的顶部或尽可能靠近顶部提供一个电缆支撑，并按导体尺寸确定的间隔安装中间支撑。

Source: Wire & Cable Tips – Hanging Tough with Vertical Cable Supports

Proper Installation Technique 正确的安装技术

Correct installation of Kellem grips requires attention to several critical details:

• Mesh Orientation: The mesh must be installed so that tension causes the grip to tighten around the cable. The “throat” or narrow end should face the load direction. 网格方向：必须安装网格，使张力使夹具在电缆周围收紧。
• Taping Requirement: Always apply vinyl electrical tape starting 2-3 inches (5-7.6 cm) from the grip tail and extending 2-3 inches onto the cable jacket. This prevents accidental release and ensures maximum reliability. 胶带要求：始终从夹具尾部开始2-3英寸处应用乙烯基电工胶带，并延伸到电缆护套2-3英寸。
• Swivel Integration: For applications involving cable rotation or twist, always install a swivel between the grip eye and the mounting point. This allows the cable to rotate freely without transferring torque to the support structure. 旋转整合：对于涉及电缆旋转或扭曲的应用，始终在夹具环和安装点之间安装旋转接头。
• Protective Covering: Use rubber or plastic tape over the grip surfaces that contact cable trays or sheaves during installation to prevent scoring or damage. 保护性覆盖：在安装期间，在接触电缆桥架或滑轮的夹具表面上使用橡胶或塑料胶带，以防止划伤或损坏。

Sources: Hubbell – Wire Management Solutions Installation Guide, J Harlen Co – Kellems Grip Installation Guidelines

Application-Specific Considerations 特定应用注意事项

Mining and Underground Operations 采矿和地下作业

(N)SHTÖU cables in mining applications face extreme conditions including abrasion, chemical exposure, and temperature fluctuations. Cable grips must be selected with adequate corrosion resistance (stainless steel or tin-coated bronze recommended) and installed with additional support intervals beyond NEC minimums to account for shock loads from mobile equipment. (N)SHTÖU电缆在采矿应用中面临极端条件，包括磨损、化学品暴露和温度波动。

Port Container Handling and STS Cranes 港口集装箱处理和STS起重机

Ship-to-Shore (STS) cranes and container handling equipment require (N)SHTÖU cables that can withstand continuous flexing and high-speed reeling operations. Vertical suspension systems must account for wind loads and dynamic forces from crane movement. Marine-grade stainless steel grips are essential due to salt spray and humidity exposure. 岸到船（STS）起重机和集装箱处理设备需要能够承受连续弯曲和高速卷筒操作的(N)SHTÖU电缆。

Spreader Applications (Vertical Reeling) 吊具应用（垂直卷筒）

Spreader bars and lifting frames create particularly demanding conditions for vertical cable suspension. The (N)SHTÖU-V variant should always be specified for these applications, and cable grips must be rated for dynamic loads at least 2.0 times the static cable weight. Support points should be located every 20-25 meters for these applications rather than following standard NEC spacing. 吊具和起重架为垂直电缆悬挂创造了特别苛刻的条件。应始终为这些应用指定(N)SHTÖU-V变型。

Source: Tratos Group – TRATOSMART NSHTOU-J for Crane Applications

Common Installation Mistakes to Avoid 避免常见安装错误

• Using pulling grips instead of support grips: This is a code violation and creates immediate safety hazards. Pulling grips are not rated for continuous vertical load bearing. 使用牵引夹具而不是支撑夹具：这是违反规范的行为并造成直接的安全隐患。
• Incorrect grip sizing: Oversized grips will slip under load; undersized grips will damage cable insulation and reduce holding power. 夹具尺寸不正确：过大的夹具会在负载下滑动；过小的夹具会损坏电缆绝缘并降低握持力。
• Omitting taping: Failure to properly tape the grip tail to the cable significantly reduces reliability and can result in grip failure. 省略胶带：未能正确地将夹具尾部用胶带固定到电缆上会显著降低可靠性。
• Installing grips in reverse: The mesh must tighten under load. Reversed installation will cause the grip to loosen and eventually fail. 反向安装夹具：网格必须在负载下收紧。反向安装会导致夹具松动并最终失效。
• Exceeding working load limits: Never exceed the published WLL. The 5:1 safety factor accounts for dynamic loads, but additional factors may be required for shock loads or continuous cycling applications. 超过工作负荷极限：切勿超过公布的工作负荷极限。