1. What is SIS Switchboard Wire?
SIS wire, short for Switchboard Installation Service wire, is a single-conductor copper wire primarily designed for use in switchboards, panel boards, and control cabinets.
1.1 Key Technical Specifications of SIS Wire
| Attribute | Specification |
|---|---|
| Conductor | Bare or tinned copper (ASTM B3/B8/B33 compliant) |
| Temperature Rating | 90°C continuous operation |
| Voltage Rating | 600V |
| SIS wire insulation | Cross-linked Polyethylene (XLPE), thermoset |
| Flame Test Rating | Passes VW-1 flame test |
| Recommended Use | Dry environments, enclosed switchgear, panels |
| Compliance Standards | UL 44, CSA, NEC Article 310 |
1.2 Typical Applications of SIS Type Wire
Electrical switchboards
Industrial control cabinets
Commercial panelboards
Enclosed dry environments requiring clean, compact wiring
Thanks to SIS wire insulation made of XLPE, these wires offer excellent heat resistance and mechanical durability, making them ideal for high-reliability settings.
2. Overview of Other Common Electrical Wire Types
Here's a quick snapshot of other frequently used electrical wires to better understand how SIS type wire compares:
| Wire Type | Insulation | Temp Rating | Application Environment | Flexibility |
|---|---|---|---|---|
| SIS Wire | Thermoset XLPE | 90°C | Dry, enclosed spaces | Medium |
| THHN/THWN | PVC + Nylon | 75–90°C | Indoor, damp locations | Medium |
| XHHW | XLPE | 90°C | Wet, outdoor | Medium |
| MTW | PVC | 60–90°C | Industrial machinery | High |
| USE | XLPE | 90°C | Underground, outdoor | Medium |
| TFFN | PVC + Nylon | 60–90°C | Equipment interconnect | High |
3. Detailed comparative analysis of SIS Wire and other wires
1. Insulation Performance
SIS wire insulation uses thermoset XLPE, which offers better performance in high-heat and harsh environments.
In contrast, THHN and TFFN wires use thermoplastic PVC insulation that can degrade faster under prolonged heat.
| Wire Type | Insulation Type | Heat Tolerance | Aging Resistance |
|---|---|---|---|
| SIS | Thermoset XLPE | High | Strong |
| THHN | Thermoplastic PVC | Medium | Moderate |
| XHHW | Thermoset XLPE | High | Strong |
| TFFN | PVC + Nylon | Medium | Moderate |
2. Thermal & Flame Resistance
SIS switchboard wire is rated for 90°C continuous operation and passes the VW-1 flame test, making it ideal for installations where fire safety is critical.
Advantage: Resists melting and does not propagate flames.
Comparison: THHN may meet basic flame resistance, but its plastic insulation can deform under long-term high heat.
3. Flexibility & Installation Ease
MTW and TFFN are highly flexible and used in environments requiring movement or bending.
SIS wire has moderate stiffness, making it ideal for neat, linear installations in switchboards and control panels.
4. Environmental Suitability
| Environment | Recommended Wire Type | Explanation |
|---|---|---|
| Dry control panels | SIS switchboard wire | XLPE insulation, high mechanical strength |
| Wet or damp areas | XHHW / THWN | Water-resistant jackets |
| Underground use | USE | Rated for direct burial |
| Internal machinery | MTW | Flexible, vibration-resistant |
4. Benefits & Use Cases of SIS Type Wire
Key Advantages
Superior SIS wire insulation with XLPE
High resistance to heat, flame, and mechanical damage
Neat layout in control cabinets and electrical panels
Certified under UL and CSA standards
Ideal Applications
Data center switchboards
Industrial automation cabinets
Commercial high-rise panelboards
5. When to Use SIS Wire vs. Other Types
| Application Requirement | Recommended Wire Type |
|---|---|
| High temperature, dry area | SIS switchboard wire |
| Wet or outdoor installation | XHHW / USE |
| Flexible equipment wiring | MTW / TFFN |
| General building wiring |
THHN / THWN |
Dongguan Greater Wire & Cable Co., Ltd. export range in the Americas extends from Canada to Ecuador in South America, and has served many power, communication and transportation projects. We will apply this experience to your project. Please contact us immediately and we will develop the most suitable cooperation plan for you.