H1: ANSI 57-3 Insulator — 12.5kN Porcelain Line Post Insulator for Distribution Lines
The ANSI 57-3 Insulator is a solid-core porcelain line post insulator designed for mechanical support and electrical insulation of conductors in overhead power distribution lines. Manufactured in strict accordance with ANSI C29.7 standards, this insulator provides reliable performance for distribution applications up to 46kV. The vertical tie-top design features a top groove for conductor tie wire, ensuring easy installation and stable performance under extreme temperature cycling. Whether used in crossarm-mounted distribution lines, pole-top structures, or dead-end applications, the ANSI 57-3 Insulator offers a cost-effective and durable solution for modern distribution infrastructure.
H2: ANSI 57-3 Insulator Technical Specifications
The ANSI 57-3 Insulator features a cantilever strength of 12.5kN (2,800lbs) , making it ideal for line post applications in distribution networks.
Key electrical and dimensional ratings are detailed below:
| S/N | Technical Standard Particulars/Details | Brown (57-3B) | Gray (57-3G) |
| 1 | Product Item No./SKU Code | 57-3B | 57-3G |
| 2 | Glaze Color | Brown | Gray |
| 3 | ANSI Class | 57-3 | 57-3 |
| 4 | Figure No. (per ANSI C29.7) | 3 | 3 |
| 5 | Type / Mounting | Vertical Tie-Top / 3/4″ NC | Vertical Tie-Top / 3/4″ NC |
| 6 | Reference Height / Length /mm (in.) | 381 (15) | 381 (15) |
| 7 | Insulating Part Diameter /mm (in.) | 165 (6-1/2) | 165 (6-1/2) |
| 8 | Cantilever Strength /lb(kN) | 2800 (12.5) | 2800 (12.5) |
| 9 | Low-frequency Dry Flashover Voltage (kV) | 125 | 125 |
| 10 | Low-frequency Wet Flashover Voltage (kV) | 95 | 95 |
| 11 | Creepage Distance /mm (in.) | 737 (29) | 737 (29) |
| 12 | Dry Arcing Distance /mm (in.) | 311 (12-1/4) | 311 (12-1/4) |
| 13 | Positive Critical Impulse Flashover (kV) | 200 | 200 |
| 14 | Negative Critical Impulse Flashover (kV) | 260 | 260 |
| 15 | Radio Influence Voltage – Test Voltage (kV) | 30 | 30 |
| 16 | Radio Influence Voltage – Max RIV (μV) | 200 | 200 |
| 17 | Net Weight (approx.) /kg | 11 | 11 |
| 18 | Applicable Standard | ANSI C29.7 | ANSI C29.7 |
H2: Material & Construction
Every unit of the ANSI 57-3 Insulator is made from high-grade wet-process porcelain, fired at high temperature to achieve maximum density and near-zero porosity. The solid-core line post design ensures easy handling and reliable performance under extreme thermal cycling. The hard, glossy glaze coating offers good self-cleaning properties, reducing maintenance frequency. The vertical tie-top design features a top wire groove that seats a 1-15/16-inch diameter mandrel per ANSI C29.7 standards, widely applied in overhead distribution lines. Metal parts are made of galvanized malleable iron, ductile iron, steel, or aluminum, with ferrous parts hot-dip galvanized per ASTM A153. Both brown and gray glaze colors are available. For more on porcelain manufacturing standards, visit the International Electrotechnical Commission (IEC).
H2: ANSI 57-3 Insulator Applications & Installation
The ANSI 57-3 Insulator is widely used in overhead power distribution lines, typically installed on crossarms and pole-mounted structures. It is ideal for:
- Overhead distribution line conductor support
- Crossarm-mounted applications
- Pole-top structures
- Dead-end and angle applications in distribution networks
The vertical tie-top design allows easy mounting using conductor tie wires, with 3/4″ NC threaded base mounting. Explore our full range of suspension insulators and transmission hardware for more options.
H2: ANSI 57-3 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 57-3 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 C29.7, 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. Design tests — such as dry flashover, wet flashover, critical impulse flashover, radio influence voltage, and thermal shock — are performed per ANSI C29.7 standards on new designs. Quality conformance tests including porosity, galvanizing, and cantilever-strength tests are conducted on each lot. 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 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 57-3 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 57-3 Insulator
When selecting an ANSI 57-3 Insulator for your distribution project, quality and reliability are paramount. Our ANSI 57-3 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 57-3 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 57-3 Insulator is available with short lead times. Contact us today to learn how the ANSI 57-3 Insulator can enhance your distribution grid reliability.
