Choosing the wrong power cord can lead to safety risks, performance issues, and unnecessary costs. SO and SJ type cords may look similar at first glance, but they are designed for very different applications. Understanding their differences is essential for engineers, buyers, and project managers who want reliable power connections. In this guide, we clearly explain what SO and SJ cords are, how they differ, where they are used, and how to choose the right option-helping you make confident, informed decisions faster.
What Is an SO Cord?
An SO cord is a heavy-duty portable power cable designed for demanding industrial and commercial environments.
The designation typically breaks down as follows:
- S – Service cord
- O – Oil-resistant insulation and jacket
Common types include SOOW, where the additional "W" indicates suitability for outdoor and water-resistant use.
Key characteristics of SO cords:
- Rated for 600 volts
- Thick, durable insulation and jacket
- Excellent resistance to oil, abrasion, chemicals, and moisture
- Long service life even in harsh environments
SO cords are widely used in factories, construction sites, mining equipment, generators, and other heavy-duty applications where safety and durability are critical.
What Are SJ Type Cords?
SJ type cords are classified as junior service cords, designed for lighter-duty applications.
The naming typically includes:
- S – Service cord
- J – Junior service (lighter construction than SO cords)
Common types include SJT and SJTW.
Key characteristics of SJ cords:
- Rated for 300 volts
- Thinner insulation and jacket
- More flexible and lightweight
- Suitable for indoor or light commercial environments
SJ cords are commonly used for household appliances, office equipment, power strips, and light-duty extension cords.
Key Differences Between SO and SJ Type Cords
| Feature | SO Type Cord | SJ Type Cord |
|---|---|---|
| Voltage Rating | 600V | 300V |
| Construction | Thick, heavy-duty | Thinner, lightweight |
| Durability | Extremely high | Moderate |
| Oil Resistance | Yes | Limited (depends on type) |
| Outdoor Use | Suitable (e.g., SOOW) | Limited |
| Typical Environment | Industrial, harsh conditions | Residential & light commercial |
| Cost | Higher | Lower |
| Service Life | Longer | Shorter |
This comparison makes it clear that SO cords are built for performance and safety, while SJ cords focus on flexibility and cost-efficiency.
How to Choose the Right Cord?
When selecting between SO and SJ type cords, consider the following factors:
- Voltage Requirements
Equipment over 300V requires SO cord.
- Operating Environment
Oil, moisture, abrasion, or outdoor use → SO cord
Clean, dry indoor use → SJ cord
- Load & Safety Standards
High-load or mission-critical equipment benefits from SO cord durability.
- Compliance & Certification
Always ensure UL, VDE, CSA, or CB compliance depending on your market.
Choosing the right cord not only improves safety but also reduces downtime and long-term replacement costs.
Typical Application Examples
SO Cord Applications
- Industrial machinery
- Construction tools
- Portable generators
- Mining and oil-field equipment
- Heavy-duty extension cords
SJ Cord Applications
- Home appliances
- Office equipment
- Power strips
- Light-duty extension cords
- Commercial electronics
Why Choose Our SO Cords?
At Dongguan Greater Wire & Cable Co., Ltd., we specialize in high-quality SO cords engineered for reliability, safety, and long-term performance.
Our Key Advantages:
✅ 30 years of manufacturing experience
✅ Full range of certifications: VDE, UL, CB and more
✅ Complete SO cord product series, multiple specifications available
✅ Large inventory with fast delivery
✅ Support for small orders to large-scale batch production
✅ Professional pre-sales and after-sales technical support
Our SO cords help customers:
Reduce maintenance and replacement costs
Improve equipment safety and uptime
Simplify sourcing with one reliable supplier
Whether you're working on a small project or a large industrial deployment, our team is ready to support you with fast response, expert consultation, and stable supply.
Contact Us Today:
- Company: Dongguan Greater Wire & Cable Co., Ltd.
- Tel / WhatsApp / WeChat:
+86 135 1078 4550
+86 136 6257 9592
- Email: manager01@greaterwire.com