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What is Primary Wire?

Automotive Primary Wire is the most common type of general-purpose wire used in automotive applications. Primary Wire is a single conductor wire designed with a smooth surface, making it ideal for use in wire looms and other wiring management systems. All of our primary wires feature stranded copper conductors and meet SAE J-1128, Ford, and Chrysler Specs. There are two main types of Primary Wire: Cross-Linked and PVC.

Cross-Linked Primary Wire

There are three types of Cross-Linked Primary Wires: TXL, SXL, and GXL. All three feature a bare copper conductor and cross-linked polyethylene (XLPE) insulation. This cross-linked insulation is extruded under heat and pressure to change the molecules of the material. All cross-linked primary wires have a voltage rating of 50V and a temperature range of -51°C to +125°C. The main differences between the three types of cross-linked wires are their insulation thicknesses and the Ford and Chrysler Specs they meet.

TXL GXL SXL
Insulation Type Cross-Linked PE Cross-Linked PE Cross-Linked PE
Insulation Thickness Thinnest Wall Thin Wall Standard Wall
Temperature Rating -51°C to +125°C -51°C to +125°C -51°C to +125°C
Ford Specification M1L-123A M1L-85B M1L-85A
Chrysler Specification MS-8288 MS-8900 MS-5919
Insulation Thickness of 18AWG 0.016 in. 0.023 in. 0.030 in.
Weight of 18 AWG 6.9 lbs/MFT 8.0 lbs/MFT 9.5 lbs/MFT

These wires are ideal for use in high-temperature industrial applications, including engine compartments in trucks, trailers, boats, and other automotive vehicles. This type of primary wire is extremely durable and can withstand abrasion. Because of their wide temperature range, these cables are also flexible in colder temperatures. Our GXL and SXL wires are available in gauge size 20 AWG to 8 AWG. TXL Wire is available from 22 AWG to 8 AWG.

Shop TXL Wire     Shop SXL Wire     Shop GXL Wire

PVC Primary Wire

There are also three types of PVC Primary Wires: GPT, HDT, and TWP. These wires also feature a stranded bare copper conductor. However, as their name implies, they feature PVC insulation. While these wires also have a voltage rating of 50V, their temperature ranges vary greatly. GPT wire and HDT wire have a temperature range of -40°C to 80°C, but TWP wire is rated to +105°C. These wires are also differentiated by their wall thickness and Ford and Chrysler Specs.

TWP GPT HDT
Insulation Type PVC PVC PVC
Insulation Thickness Thinnest Wall Standard Wall Heavy Wall
Temperature Rating -40°C to 105°C -40°C to +85°C -40°C to +85°C
Ford Specification M1L-120A M1L-56A M1L-50A
Chrysler Specification MS-7889 MS-3450 MS-3494
Insulation Thickness of 18AWG 0.016 in. 0.023 in. 0.036 in.
Weight of 18 AWG 7.1 lbs/MFT 8.3 lbs/MFT 11.0 lbs/MFT

Due to their varying temperature ratings and wall thicknesses, these wires have varying uses. TWP has the thinnest wall and is lead-free. It is ideal for use in automotive applications that require a small diameter and minimal weight. GPT Wire is a standard-wall wire. GPT wire is not designed for prolonged exposure to outdoor elements so it is best used in interior applications. HDT wire has the heaviest wall of all the PVC automotive wires. It is ideal for use as surface wiring in cars, trucks, RVs, and buses.

Shop HDT Wire     Shop GPT Wire     Shop TWP Wire

Value-Added Services

All of our automotive primary wires can be customized with value-added services to make identification easy. Popular value-added services include adding up to three stripes (also known as tracers) for wires used in wire harnesses. Jacketing can also be printed with custom text, numbers, and even company logos! With our variety of value-added services and spool sizes, we're sure to have the perfect wire for your next automotive application.

Shop All Primary Wire

Primary Wire is one of the many automotive wires that we carry. Allied Wire and Cable also offers battery cable, fusible links, brake cable, and more! What to learn more about Automotive Wire? Read our Automotive Wire and Battery Cable FAQs.