Allied Encyclopedia: UL3239 and UL10475

What type of hookup wire features a wide range of high voltage ratings, up to 60kV? You may have guessed it—we’re talking about UL3239 wire.

UL 3239 features a single conductor, available in a variety of sizes depending on the conductor material.

View the chart below for size ranges and corresponding conductor materials of UL 3239:

UL 3239 Conductor Options
Conductor Material Size Range Notes
Copper 10-24 AWG Can be tinned, silver or nickel plated; heat bonded or overcoated
Nickel 10-24 AWG
Aluminum 10-12 AWG Permitted for a 90°C maximum operating temperature
Resistance Wire 20-27 AWG Solid or Stranded
Coated High Strength Copper 10-24 AWG Solid or Stranded; minimum 90% conductivity

According to the UL 3239 spec, the insulation can be extruded or non-extruded thermoplastic and/or thermosetting. This high temperature hook up wire has a temperature range of -40°C to +150°C, but depending on the material, UL 3239 can be rated up to 200°C. The voltage is dependent on the size of the cable, with a range up to 60kV, typically found in increments of 5kV. The insulation thickness increases to accommodate the high voltage rating, resulting in high outer diameters depending on the voltage of the cable.

A similar style high temperature, high voltage hook up wire is UL 10475. The spec for UL 10475 states the the conductor, size 2 AWG to 30 AWG can be solid or stranded, and requires the insulation to be either PTFE or Silicone Rubber. UL10475 wire is rated up to 200°C and up to 50kV.

UL 3239/10475 wire

UL 3239 wire

Many manufacturers group these two UL style wires together since the specs overlap. Since UL3239 spec stops at 10 AWG, the spec allows for a similar product to be extended down to 2 AWG as UL 10475. The wire Allied carries is made with nickel-plated copper and silicone rubber, which is easy for stripping and has high dielectric strength. Both must pass vertical flame tests, however UL3239 must also pass the VW-1 flame test.

These wires are recommended for use in high temperature electronic devices, like stoves, heaters, furnaces and dryers. UL 3239 and UL10475 are also good options for applications involving small areas of wiring as well, like in signs, motors and lighting fixtures.

For more information and to see full UL 3239/10475 specs, visit our UL3239/10475 page.

About awcwire
Allied Wire & Cable is a value-added manufacturer and distributor of electrical wire and cable, tubing, and more. We are a family owned and operated company, serving a wide range of industries, including the military, automotive, aerospace, and telecommunications markets. Allied is headquartered in Collegeville, PA. Additional locations can be found across the US, in Phoenix, AZ; Bedford, NH; Pewaukee, WI; Rochester, NY, Tampa, FL; and Mt. Juliet, TN. For more information on Allied, visit our main website at

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