Cables can be installed in environments with harsh conditions and high ambient temperatures, but selecting the right cables for the correct environmental conditions is essential to ensure the cable’s expected life span will not be affected. The use of wire and cable products outside their designed temperature range can result in premature and often expensive failures in service.

Understanding High-Temperature Wire

High-temperature wire is often defined as a wire with a temperature rating of 125°C or higher, although high-temperature can also refer to temperature ratings as low as 90°C. High-temperature cables can either be single-conductor or multiconductor. These products commonly consist of a conductor (usually annealed, tinned copper, copper-plated or nickel-coated copper) and insulation. High-temperature wires may also have an additional jacket consisting of a fiberglass braid or K-fiber material.

Two key components to ensure high-temperature wires are suitable for the application are the wire’s temperature rating and ampacity. Temperature ratings can be defined as the maximum continuous temperature that a wire can withstand during its lifetime. If a cable’s temperature rating is not suitable for the environment and ambient temperature, the expected lifespan of the cable could be affected.

The ampacity is the maximum current an insulated conductor can safely carry without exceeding its insulation and jacket temperature limitations. If the cable is undersized, the heat produced by circuit load may exceed the cable’s temperature rating and the cable may be compromised. For more information, please see Anixter’s Wire Wisdom Wire and Cable Ampacity Rating.

High-Temperature Cable Standards

High-temperature wire can be classified as Appliance Wiring Material (AWM) meeting UL 758 Appliance Wiring Materials. Even though AWM wires are not considered to be “UL Listed” products, they are Recognized Components that can be used in UL Listed products. If a high-temperature wire is to be considered a UL Recognized Component, the wire follows the guidelines that are detailed by UL 758 through a UL style page. This style page lists specifications on gauge size range, insulation material, temperature rating and voltage rating. Some UL AWM styles can be dual listed with Canadian standards, such as UL AWM 3284 and CSA CL1254. For more information, please see Anixter’s Wire Wisdom Understanding and Identifying UL AWM Styles.

In addition to high-temperature cables meeting AWM requirements, high-temperature products can also meet and be UL Listed to the UL 83A Fluoropolymer Insulated Wire standard. UL 83A provides requirements on the cable’s construction and test performance for high-temperature listed products. Performance tests include long term-aging of insulation and insulation resistance testing

The Different Styles of High-Temperature Wire

Due to the wide range of temperature ratings and applications available for high-temperature wire, there are many different agency approvals available. High-temperature wires can be UL Recognized per UL 758, UL Listed per UL 83A or meet CSA standards.

Table 1 provides some common high-temperature wire types that meet various UL AWM Styles per UL 758 and/or CSA standards.

Trade Name

Description

Temperature

Voltage

Size

UL Styles,
CSA Standards

EPDM

Ethylene proplyene diene monomer

125ºC to 150ºC

600 V

18 AWG to
4/0 AWG

UL 3284,
UL 3374;
CSA 1254

SRK

Silicone rubber with K-fiber jacket

200ºC

600 V

18 AWG to
4/0 AWG

UL 3071, UL3074,
UL 3075, UL 3125,
UL 3126;
CSA SEW-2 3410

TGGT

PTFE/glass

250ºC

600 V

24 AWG to 4/0 AWG

UL 5256,
UL 5196

EPDM

Ethylene proplyene diene monomer

125ºC to 150ºC

600 V

18 AWG to
4/0 AWG

UL 3284,
UL3374;
CSA 1254

Table 1: Common UL Style High-temperature Wire Types

In addition to the AWM high-temperature wires, Table 2 provides examples of UL Listed high-temperature wires per UL 83A.

UL Listed Name

Description

Temperature

Conductor Metal

Size

Voltage

FEP

Fluorinated ethylene propylene

90ºC (200ºC special applications)

Soft-annealed copper

14 AWG to
2 AWG

600 V

PFA

Perfluoroalkoxy

90ºC (200ºC special applications)

Soft-annealed copper

14 AWG to
4/0 AWG

600 V

TEE

Tetrafluoroethylene

250ºC

Nickel-coated copper or nickel-base alloy

14 AWG to
4/0 AWG

600 V

ZW

Ethylene Tetrafluoroethylene

90ºC (200ºC special applications)

Soft-annealed copper

14 AWG to
2 AWG

600 V

Table 2: UL Listed High-temperature Wire Types

Applications of High-Temperature Wire

As mentioned above, high-temperature wire can be found in environments with elevated temperatures and harsh conditions. These applications commonly include motor leads and internal wiring of appliances, such as refrigeration equipment, heat pumps, clothes dryers, lighting fixtures, commercial and industrial ovens, room cooler units and electrical ranges. High-temperature wire can also be found in steel mills, glass plants and chemical plants.

Table 3 provides common applications where high-temperature wires are commonly installed. Depending on the application, further information such as UL listings, cable size and other environmental conditions may be required to select the correct product.

High-Temperature Application

ºC

ºF

Wire Trade/List Name



Apparatus and Motor
Lead Wire

150

302

SRG

200

392

SRK, FEP

250

482

TGGT, TKGT

450

842

MG



Appliance and Fixture Wire

150

302

SRML, SF-2, SEW-2

250

482

TGGT, TKGT, TFE

450

842

MG, MGT


Control Cable

200

392

SRGK, SRGT, SRK

250

482

TKGT, TKGK


Heating Cable

200

392

PFA

450

842

MG

Instrumentation Cable

250

482

TKGT, GKGK


Power Cable

200

392

SRGK, SRGT, SRK, FEP,TFE, PFA

250

482

TKGT

Table 3: High-temperature Wire Applications


 

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