UL Cord Construction and Ratings
Within electrical wiring, UL cord ratings and construction standards play a crucial role in ensuring safety and efficiency. Understanding the types of cords, their construction, temperature ratings, and voltage ratings is essential when choosing the right types of wiring solutions for various applications. This guide is aimed to help one navigate through the different UL cord types and their characteristics, enabling one to make informed decisions when selecting the right cord for your electrical needs.
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Cordage Construction and Material Considerations
Insulation and Jacket Materials
The materials used for conductor insulation and outer jackets are critical for ensuring the cord's performance under various conditions. These include:
- Rubber: Known for its flexibility and durability. Commonly used in both light- and heavy-duty cords.
- Plastic: Provides higher heat resistance and used in thermoplastic cords.
- Elastomer: Brings flexibility and heat resistance making it suitable for high-temperature applications.
- Neoprene: A highly durable and oil-resistant material, often found in industrial cords.
Temperature and Voltage Ratings
The cord types are rated for specific temperatures and voltage limits. This dictates the use in various applications.
- Low-Temperature Ratings (60°C): Suitable for general household use and light-duty appliances.
- High-Temperature Ratings (90°C and above): Best for industrial equipment and heating appliances.
- Voltage Ratings: Ranges from 250V to 600V depending on cord construction and intended application.
| Cord Type* | AWG Size Range | Number of Conductors | Conductor Insulation | Jacket** | Temperature Rating*** | Voltage Rating | |
| Std. | Other | ||||||
| TPT | 27 (Tinsel) | 2 | 0.030 Plastic | 60 | 250 | ||
| SP-1 | 18 | 2 or 31 | 0.030 Rubber | 60 | 300 | ||
| SPT-1 | 18 | 2 or 31 | 0.045 Rubber | 60 | 75, 90, 105 | 300 | |
| SP-2 | 18-16 | 2 or 31 | 0.045 Rubber | 60 | 300 | ||
| SPT-2 | 18-16 | 2 or 31 | 0.045 Plastic | 60 | 75, 90, 105 | 300 | |
| SP-3 | 18-12 | 2 or 31 | 0.060 Rubber2 | 60 | 300 | ||
| SPT-3 | 18-10 | 2 or 31 | 0.060 Plastic2 | 60 | 75, 90, 105 | 300 | |
| TS | 27 (Tinsel) | 2 | 0.015 Rubber | 0.031 Rubber | 60 | 125 | |
| TST | 27 (Tinsel) | 2 | 0.015 Plastic | 0.031 Plastic | 60 | 125 | |
| SV | 18 | 2 or 31 | 0.015 Rubber | 0.030 Rubber | 60 | 75, 90 | 300 |
| SVE | 18 | 2 or 31 | 0.015 Elastomer | 0.030 Elastomer | 105 | 300 | |
| SVEO | 18-17 | 2 or 31 | 0.015 Elastomer | 0.030 Elastomer | 105 | 300 | |
| SVO | 18 | 2 or 31 | 0.015 Rubber | 0.030 Neoprene~ | 60 | 75, 90 | 300 |
| SVT | 18-17 | 2 or 31 | 0.015 Plastic | 0.030 Plastic | 60 | 75, 90, 105 | 300 |
| SVTO | 18-17 | 2 or 31 | 0.015 Plastic | 0.030 Plastic | 60 | 75, 90, 105 | 300 |
| SJ | 18-10 | 2, 3, 4 | 0.030 Rubber3 | 0.030 Rubber2 | 60 | 75, 90 | 300 |
| SJE | 18-10 | 2, 3, 4, 5 | 0.030 Elastomer2 | 0.030 Elastomer2 | 105 | 300 | |
| SJEO | 18-10 | 2, 3, 4, 5 | 0.030 Elastomer2 | 0.030 Elastomer2 | 105 | 300 | |
| SJO | 18-10 | 2, 3, 4 | 0.030 Rubber3 | 0.030 Neoprene~3 | 60 | 75, 90, 105 | 300 |
| SJOOW | 18-10 | 2, 3, 4 | 0.030 Rubber3 | 0.030 Neoprene~3 | 60 | 75, 90, 105 | 300 |
| SJT | 18-10 | 2, 3, 4 | 0.030 Plastic3 | 0.030 Plastic3 | 60 | 75, 90, 105 | 300 |
| SJTO | 18-10 | 2, 3, 4 | 0.030 Plastic3 | 0.030 Plastic3 | 60 | 75, 90, 105 | 300 |
| S | 18-2 | 2 or more | 0.030 Rubber2 | 0.060 Rubber2 | 60 | 75, 90 | 600 |
| SE | 18-2 | 2 or more | 0.030 Elastomer2 | 0.060 Elastomer2 | 105 | 600 | |
| SEO | 18-2 | 2 or more | 0.030 Elastomer2 | 0.060 Elastomer2 | 105 | 600 | |
| SO | 18-2 | 2 or more | 0.030 Rubber2 | 0.060 Neoprene~2 | 60 | 75, 90 | 600 |
| SOOW | 18-2 | 2 or more | 0.030 Rubber2 | 0.060 Neoprene~2 | 60 | 75, 90 | 600 |
| ST | 18-2 | 2 or more | 0.030 Plastic2 | 0.060 Plastic2 | 60 | 75, 90, 105 | 600 |
| STO | 18-2 | 2 or more | 0.030 Plastic2 | 0.060 Plastic2 | 60 | 75, 90, 105 | 600 |
| STOOW | 18-2 | 2 or more | 0.030 Plastic2 | 0.060 Plastic2 | 60 | 75, 90, 105 | 600 |
| HPN | 18-12 | 2 or 31 | 0.045 Neoprene | 90 | 105 | 300 | |
| HSJ | 18-12 | 2, 3, 4 | 0.030 Neoprene2 | 0.030 Rubber2 | 90 | 300 | |
| HSJO | 18-12 | 2, 3, 4 | 0.030 Neoprene2 | 0.030 Neoprene~2 | 90 | 300 | |
| HS | 14-12 | 2, 3, 4 | 0.045 Neoprene2 | 0.060 Rubber2 | 90 | 300 | |
| HSO | 14-12 | 2, 3, 4 | 0.045 Neoprene2 | 0.060 Neoprene~2 | 90 | 300 | |
* Types SVO, SVTO, SJO, SJOOW, SJTO, SO, SOOW, STO HSJO and HSO have jackets which are also recognized for oil resistance at maximum temperature of 60C. Types SJ, SJO, SJT, SJTO, S, SO, ST and STO may also be printed as “OOW” infering an oil resistant insulation and an oil resistant and moisture resistant jacket. Acceptable for indoor/outdoor use. 3-wire SJT may be made in special low-leakage constructions for medical equipment cords.
** Where no jacket is shown, the construction is integral or flat style with insulation also serving as jacket.
*** For cordage ratings higher than 60C, the temperature limit is printed on the outside of the jacket. This does not apply to heater cordage type HPN, rated 90C or 105C. Also, for heater cordage types HSJ, HSJO, HS and HSO, the core is rated 90C while temperature printed on outside applies only to jacket.
1 Recognized in three conductors where third or center conductor (with green of treen/yellow stripe) is used for equipment grounding.
2 Insulation and jacket thickness depend on cordage size. Thickness shown are for 18 and 16 AWG.
3 Insulation and jacket thickness depend on cordage size. No. 12 AWG requires .030” conductor insulation thickness and .045” jacket thickness. No. 10 AWG requires .045” conductor insulation thickness and .060” jacket thickness.
Chlorosulfonated polyethylene and other UL Listed materials may be used as jacketing material for such cordage as SVO, SJO, SO and HPN to provide oil resistance and/or colors with excellent stability in all shades.
NOTE Types TPT, SPT-1, SPT-2, SPT-3, HPN (two conductors only) and SVO, SVT, SJO, SJT, SO and ST may be made in retractile form.
The term Elastomer refers to thermoplastic elastomer.
Choosing the Right UL Cord for Your Application
During the selection process for a UL cord, it is important to consider the environment in which it will be used, the power requirements of the equipment, and any specific material or insulation needs. Light-duty applications typically have cords like SPT and SV, while heavy-duty applications typically have cords like SOOW and SJOOW. By understanding the different UL cord types and their ratings, this can help ensure that electrical wiring is safe and compliant with industry standards.
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