SWITCHBOARD SIS HIGH TEMP WIRE

Switchboard SIS High Temp Wire, standing for Stranded Insulated Switchboard, is a specialized 600 Volt, 125°C electrical wire primarily designed for control and power circuits within switchboards, panelboards, and industrial control equipment. It features flexible stranded tinned copper conductors and robust Cross-Linked Polyethylene (XLPE) insulation, providing excellent resistance to heat, moisture, chemicals, oil, and abrasion. Read our Switchboard SIS High Temp Buyers Guide.

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SIS stands for Synthetic Insulated Switchboard wire (historically referred to as Stranded Insulated Switchboard). It is a high-temperature 600V lead wire engineered specifically for internal control and power distribution wiring inside switchboards, panelboards, motor control centers (MCCs), industrial control cabinets, and commercial appliances.

  • Temperature Rating: Continuous operation up to 125°C (257°F).
  • Voltage Rating: Rated for 600 Volts maximum operating voltage.
  • Flame Resistance: Complies with both the UL Horizontal Flame Test and CSA FT2 Flame Test. (VW-1 Rated Version available in the 90°C.)

This high-temperature switchboard wire is ideal for enclosed cabinet wiring and high-heat equipment where flexibility and thermal protection are required:

  • Switchboards & Panelboards: Internal power distribution, metering loops, and control circuits.
  • Industrial Control Panels & MCCs: Relay panels, motor starters, and automation enclosures operating near heat-generating components.
  • Commercial Appliances & Transformers: Internal appliance wiring, transformer leads, switchgear, and UPS battery systems.

While THHN is a general-purpose building wire rated to 90°C, 125°C SIS wire is specifically engineered for severe panel environments:

  • Higher Heat Resistance (125°C vs 90°C): Handles elevated ambient temperatures inside tightly packed electrical enclosures without insulation degradation.
  • Won't Melt Under Thermal Overload: Utilizes thermoset Cross-Linked Polyethylene (XLPE) insulation, which chars rather than softens or melts under severe heat spikes or fault conditions.
  • Superior Routing Flexibility: Stranded copper conductors make it easier to strip, bend, and route neatly around dense terminal blocks without spring-back.

This SIS switchboard wire meets the following technical specifications:

  • UL Type AWM Style 3173: Certified under Underwriters Laboratories Appliance Wiring Material standards (600V, 125°C, XLPE insulation).
  • CSA Type CL1251: Certified by the Canadian Standards Association for 125°C 600V cross-linked switchboard/appliance lead wire.
  • Flame Ratings: Passed both UL Horizontal Flame and CSA FT2 Flame tests.

AWM Style 3173 / CSA CL1251 SIS wire is designed primarily for open, internal appliance and panel wiring. It is not generally approved as a standalone building wire in conduit under standard NEC branch circuit rules unless the wire print legend carries a dual rating (such as Type XHHW-2). Always verify your jobsite submittal requirements and local codes.

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Switchboard SIS High Temp Wire 125ºC

SIS Wire, also known as Switchboard Instrumentation Style wire, is a specialized single-conductor lead wire designed for the internal wiring of electrical switchgear, control panels, and substations. Engineered for high-voltage industrial environments, SIS wire features a stranded tinned copper conductor insulated with high-grade Cross-Linked Polyethylene (XLPE). This combination provides exceptional thermal stability and resistance to the mechanical stresses common in dense control cabinet routing.

Key Features
  • High-Performance XLPE Insulation: The thermoset cross-linked polyethylene insulation provides excellent dielectric strength and resistance to moisture, heat, and voltage stress.
  • Superior Chemical Resistance: Built to withstand harsh industrial conditions, SIS wire is highly resistant to oils, chemicals, and common hydraulic fluids.
  • UL Rating: Our SIS wire carries a UL 3173 listing, allowing for continuous operation at 90°C and peak temperatures up to 125°C.
  • Flexible Tinned Copper: The stranded tinned copper conductor prevents corrosion at connection points and offers the flexibility required for tight bends in panel boards.
Common Applications
  • Switchboards & Control Panels: The primary choice for feeding power to relays, contactors, and terminal blocks in industrial control cabinets.
  • Substation & Utility Wiring: Deployed in mission-critical utility installations where long-term stability and safety are non-negotiable.
  • Motor Control Centers (MCC): Used for internal wiring of higher-load equipment where maintaining low voltage drop is critical.
  • Power Generation Facilities: Ideal for the demanding environments of power plants, providing consistent performance under thermal cycling.
  • Panel Board Signal Wiring: Smaller gauges like 14 AWG and 16 AWG are frequently used for indicator lights and signaling circuits.
Installation Note
  • SIS wire is exclusively rated for dry locations. While its XLPE insulation offers superior heat and moisture resistance compared to standard PVC, it should not be used in applications where direct exposure to liquids or submersion is possible. For applications requiring a dual-rating for wet/dry use, ensure you select an SIS variant that is also rated as XHHW-2.