Types of insulation used on automotive wire

There are two main categories of automotive wire – PVC and Cross-Linked. The biggest difference between the two categories is temperature range, as shown below.

PVC is created by heating PVC and then extruding it through a die on the stranding. This insulation can be melted with a heat source, changing the form.

The three main types of PVC automotive wire are:
1. GPT – used for general circuit wiring and rated to 80 °C
2. TWP – lead-free, thin wall automotive wire rated to 105 °C
3. HDT – heavy wall automotive wiring rated to 80 °C

Cross-linked insulation is created by extruding polyethylene through a tube, under heat and pressure, in order to ‘cross-link’ or change the molecules of the insulation to another state. Cross-linked automotive wire can withstand much higher temperatures than PVC automotive wire.

The three most common types of cross-linked automotive wire are:
1. GXL – thin wall, most common type, works with most standard automotive connectors, rated to 125 °C

“American Autowire uses GXL wire in all kits because of the greater temperature safety range. Our GXL wire is also labeled every 2″-3″ so can can find the connection you are looking for anywhere along the harness.”

2. SXL – standard wall, rated to 125 °C
3. TXL – extra thin wall, best for applications that require minimal size and weight, rated to 125 °C