H1: ANSI 55-7 Insulator — 13kN Porcelain Pin-Type Insulator for Distribution Lines
ANSI 55-7 Insulator is a heavy‑duty pin‑type porcelain insulator designed for medium‑voltage overhead distribution lines, offering the highest mechanical strength and extended creepage distance in the ANSI 55 series for the most demanding applications. Manufactured in accordance with ANSI C29.5 standards, this ANSI 55-7 Insulator delivers reliable electrical insulation and mechanical endurance for demanding distribution applications, particularly in areas with heavy pollution, coastal salt fog exposure, or long-span requirements. Its pin‑type construction ensures easy mounting on line poles and stable performance under extreme temperature cycling from ‑40°C to +105°C. Whether used in industrial zones, coastal areas with salt fog exposure, or regions with severe pollution, the ANSI 55‑7 Insulator provides a cost‑effective and durable insulation solution for distribution infrastructure.
H2: ANSI 55-7 Insulator Technical Specifications
The ANSI 55‑7 Insulator has a cantilever (combined M&E) strength of 13kN (3,000 lbf), making it suitable for medium‑voltage distribution applications with heavier conductor loads or longer spans. Its creepage distance is 381mm (15 inches), providing superior pollution flashover performance for the most demanding environments. The dry arcing distance is 203mm (8 inches). The disc diameter is 213mm (8‑3/8 inches), and the spacing is 140mm (8‑1/2 inches). The minimum pin height is 190mm (7‑1/2 inches). The insulator uses the standard pin type mounting, fully interchangeable per ANSI dimensional requirements.
Standard glaze colors are grey or brown. Neck types available include J‑Neck.
Complete Technical Data (both glaze colors):
| S/N | Technical Standard Particulars/Details | Brown | Gray |
| 1 | Product Item No./SKU Code | 55-7B | 55-7G |
| 2 | Glaze Color | Brown | Gray |
| 3 | ANSI Class | 55-7 | 55-7 |
| 4 | Figure No. | 1 | 1 |
| 5 | Connecting hardware coupling | Pin | Pin |
| 6 | Disc diameter D/in.(mm) | 8‑3/8 (213) | 8‑3/8 (213) |
| 7 | Unit Spacing H/in.(mm) | — | — |
| 8 | Leakage distance /in.(mm) | 15 (381) | 15 (381) |
| 9 | Cantilever strength /lb(kN) | 3000 (13) | 3000 (13) |
| 10 | Tension proof /lb(kN) | — | — |
| 11 | Impact strength /in‑lb(N‑m) | — | — |
| 12 | Low‑frequency dry flashover voltage (kV) | 100 | 100 |
| 13 | Low‑frequency wet flashover voltage (kV) | 50 | 50 |
| 14 | Critical impulse flashover voltage, Positive (kV) | 150 | 150 |
| 15 | Critical impulse flashover voltage, Negative (kV) | 170 | 170 |
| 16 | Low‑frequency puncture voltage (kV) | 135 | 135 |
| 17 | Radio‑influence voltage data‑RIV (Test voltage to ground)（kV） | 22 | 22 |
| 18 | Radio‑influence voltage data‑RIV (Max. RIV at 1000kHz)（μV） | 100 | 100 |
| 19 | Net weight (kg) | 4.4 | 4.4 |
| 20 | Applicated Standard | ANSI C29.5 | ANSI C29.5 |
H2: Material & Construction
Every unit of the ANSI 55‑7 Insulator is made from high‑grade porcelain, fired at high temperature to achieve maximum density and near‑zero porosity. The pin is manufactured from hot‑dip galvanized steel, providing excellent corrosion resistance. The cement bonding between porcelain and metal parts uses high‑quality cement, ensuring stable mechanical performance under extreme thermal cycling from ‑40°C to +105°C. The hard, glossy glaze coating offers good self‑cleaning properties, reducing maintenance frequency. For more on porcelain manufacturing standards, visit the International Electrotechnical Commission (IEC).
H2: ANSI 55-7 Insulator Applications & Installation
The ANSI 55‑7 Insulator is widely used on medium‑voltage overhead distribution lines, typically at 35kV system voltage. It is ideal for:
- Industrial distribution feeders with heavy loads
- Coastal areas with severe salt fog exposure
- Regions with heavy pollution
- Long‑span rural electrification projects
The pin‑type design allows easy mounting on line poles using standard pin hardware. Standard coupling dimensions ensure full compatibility with existing pin bases and cross‑arms. Explore our full range of suspension insulators and transmission hardware for more options.
H2: ANSI 55-7 Insulator Quality & Performance Advantages
Compared to polymer alternatives, porcelain offers unmatched resistance to UV radiation, bird pecking, and scratch damage. Its glaze reduces continuous water film formation, significantly raising pollution flashover voltage. Moreover, the ANSI 55‑7 Insulator requires minimal routine maintenance and delivers a service life of over 30 years under normal operating conditions. Full testing procedures are detailed in ANSI C29.5, published by NEMA.
Every unit undergoes 100% routine electrical and mechanical testing before dispatch, including visual inspection, dimensional checks, mechanical load tests, and high‑voltage withstand tests. Prototype tests — such as temperature cycling and radio interference voltage (RIV) — are also performed per ANSI C29.5 standards. Full test reports and traceability records are provided for each batch. For installation guidance, refer to our insulator string assembly guide.
Each insulator is individually packed with foam cushioning and secured in sturdy wooden crates or corrugated cartons to prevent transit damage. We offer flexible shipping options (FOB, CIF, EXW) with lead times of 15‑30 days depending on order quantity.
For detailed datasheets, CAD drawings, or competitive pricing on the ANSI 55‑7 Insulator, please contact our sales team via the inquiry form below. We also offer OEM services and free technical consultation for distribution line design.
H2: Why Choose Our ANSI 55‑7 Insulator
When selecting an ANSI 55‑7 Insulator for your distribution project, quality and reliability are paramount. Our ANSI 55‑7 Insulator is subject to strict quality control at every production stage — from raw material inspection to final electrical testing. We understand that distribution line outages are costly, which is why each ANSI 55‑7 Insulator is designed for long‑term durability. With years of experience in porcelain insulator manufacturing, we provide competitive pricing, fast delivery, and dedicated technical support. Whether you need a small sample batch or a full container order, our ANSI 55‑7 Insulator is available with short lead times. Contact us today to learn how the ANSI 55‑7 Insulator can enhance your distribution grid reliability.
