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MTW vs THHN | Product Knockout

Wednesday, September 23, 2020

MTW wire and THHN wire are electrical PVC wires used in building applications. MTW and THHN are built in accordance with the National Electrical Code for general purpose wiring for installation in conduit or other recognized raceway. These cables share several overlapping characteristics, although there are a few distinct differences that set them apart.

What is MTW wire?

MTW stands for Machine Tool Wire, and as the name implies, its primary uses are related to the wiring of machine tools, appliances, and control cabinets. It is a PVC hookup wire and although machine tool wire is qualified for many wiring applications, it is a simply constructed wire that is made up of a highly stranded bare copper conductor. This high stranding of bare copper gives the wire its superior flexibility compared to that of THHN building wire. Also available with a tinned copper conductor, these MTW wires offer increased corrosion protection and moisture-resistance. MTW  is resistant to heat, moisture, oil, and gasoline. It is rated for up to 600V and has a temperature range of -25 °C to 90 °C. MTW wire passes the VW-1 Flame Test and meets several UL ratings including 1028, 1283, and 1284.

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What is THHN wire?

THHN wire stands for Thermoplastic High Heat-resistant Nylon, and as we can tell from the name, this wire is made of thermoplastic material (PVC insulation), can withstand high temperatures, and features a nylon jacket. THHN wire is a building wire and is primarily used to carry electrical currents to external power sources. This wire is rated for up to 600V and up to 90°C in dry locations, and 75°C in wet locations. THHN wire features either a bare copper or aluminum conductor and comes in both stranded or solid, depending on the size.

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Although both MTW wire and THHN wire are well suited for use in similar applications, there are a few characteristics that set them apart and can make a big difference when trying to decide which type of cable will best meet your needs. MTW and THHN can both feature a bare copper conductor, however, THHN is available with an aluminum conductor, depending on size and MTW wire is available with a tinned copper conductor. At the core MTW offers a higher strand count in the conductor, making it more flexible than THHN, which also features a nylon coating that further restricts movement.

MTW vs THHN Specs for Construction
  MTW Wire THHN Wire
Conductor Size 22 AWG-1000 MCM 14 AWG-1000 MCM
Conductor Type Stranded Solid or Stranded
Conductor Material Bare or Tinned Copper Bare Copper or Aluminum
Insulation Material Polyvinylchloride (PVC) Polyvinylchloride (PVC) with Nylon Jacket
Max. Temperature 90°C 90°C
Max. Voltage 600V 600V


As for the winner, the crowned champ depends on your specific application. If you’re unsure if MTW or THHN would work best for your wire and cable needs, let Allied help you out! Compare full THHN and MTW specs or give your sales rep a call at 800-472-5655 with any questions.

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