Automotive Wire Types: Why is it important to choose the right wire for your vehicle?

About Automotive Wire Types, Wires are essential for anything that requires electrical energy.

In vehicles, you need electric current to power up the headlights and speakers, which is even used in engine systems.

Moreover, these carry digital and analog signals to systems like the Powertrain Control Module (PCM).

Let’s look into different automotive wire types and their application in the automotive industry.

What is an automotive wire?

Automotive wire is any cable in the vehicle that supports such applications.

Now many types of wires are working simultaneously to keep the vehicle running.

Among them, the common cables you have heard of are the battery wire, brake wire, primary cable and speaker cable. 

Although the wires look alike, their improper use will lead to constant system failure or, worst, engine fires.

Hence, it is important to research properly and make the right choice.

Common automotive wire damages

Here are the three most common wire damages your vehicle can face.

  • Open Circuit: In an open circuit, the circuit disconnects when any of the wires are cut off, and the current path is no longer intact.
  • Short Circuit: In short-circuiting, two nodes connect even though they aren’t supposed to make any, which damages the appliance. 
  • High Resistance: High resistance becomes a major obstacle in the current flow path, causing a circuit to perform badly. It is usually due to heavy corrosion on the wire conductor or improper wiring.

Signs your car has damaged automotive wires

Cables provide a path to the electricity to flow to various vehicle components.

When the wiring is no longer stable, it will affect normal functioning. Thus you can identify the problem if the following symptoms occur.

  • Malfunctioning of Vehicle Components: Your headlights, speaker, and other parts may not turn on or are dim, which shows there is some issue going on with the wiring.
  • Blown Out Fuses: It is normal for fuses to blow out once in a while, but when this problem starts occurring frequently, it is a sign that your vehicle has cable damage.  
  • Car Starting Issues: Again, if the car is not starting at all, there is probably an issue with car wiring, like a damaged start circuit or corrosion on the PCM grounding wire. 

Automotive Wire Standards

Automotive wire bundle

Specialists inspecting wires in a vehicle

Unless you are an expert in the field, you need to know the following terms for designing the automotive wiring harness.

Automotive Wire Amperage

Amps or Amperage is the measure of load a wire can handle. It is the amount of electricity that can flow through the cable.

So, try to buy a wire with the same or more capacity than you need since overloading will cause damage to the whole system. 

For beginners, the ability of a wire to carry current directly relates to its thickness and length.

This phenomenon works similarly to the water pipe phenomenon, where the farther a tap is from the garden, the greater the time it takes to reach its destination.

Also, the pressure of the water will be less as the pipe’s length increases.

On the other hand, if you use a thick pipe, the amount of water flowing will be greater than before. 

Similarly, small applications, like signaling components, will need low potential signals and can use thin wires.

But heavy appliances like electric motors, alternators, etc., will need thicker wires for less voltage drop. 

For your help, we have mentioned a basic chart to select the wire for the potential you need. 

The basic formula for Amps, Gauge, and Length of wire

The basic formula for Amps, Gauge, and Length of wire

Automotive Wire Gauge/Size

Wire size is usually measured by gauge size. Here the smaller values, like 8 Gauge, are thick, and as you go beyond, the wires become thinner.

The size choice will depend on how much current you want to draw in for your system.

Also, you can consult your manual and purchase accordingly.

Automotive Wire Length

Since longer lengths offer higher resistance, we recommend using shorter wires for most components.

However, if the resistance is not a big deal for a circuit, you can also use long wires in them.

Automotive Conductive Material

You can find automotive wires in two conductive materials, copper and aluminum.

Copper is famous for its high conductive properties and flexibility and is less likely to corrode, but it can also be expensive at the same time.

On the other hand, Aluminum is cheaper and length-weighted, but it is less durable and can develop high resistance over time.

Hence, most vehicle engineers choose copper over aluminum.

Automotive Wire Insulation

Vehicle wires usually use PVC, GPT material, or cross-linked sheathing.

GPT has a good price here, while the cross-link insulation is heat-resistant and durable.

Hence, to choose the wire insulation, it is best to look into the type of application.

Automotive Wire Connections

There are two types of connections, solder and solderless.

Soldering is a difficult process and can lead to errors if not done properly.

Hence, with many solderless connectors, it is now easier to terminate the wires.

Common solderless connectors include ring, spade, and quick disconnect connectors.

Multi-colored Automotive Wiring, Striping, and Printing

Color-coding the automotive wires during fixture eases the repair process for different vehicles.

For example, the truck has its color scheme, from using brown for the left light to using yellow for the right light, and so on.

Similarly, the marine industry has standards that are understandable to ship experts. 

Other than colors, you can add a color strip or print the label over the wires to make it recognizable when repaired.

Automotive Wire Bundling

The cable bundling impacts its ability to release heat and cool down after the current passes.

If the bundle carries more than one wire, it can get hot and lose its current capacity.

However, if the cables are bundled loosely, they can carry a good amount of charge from one place to another.

Wire Core Type

Other than selecting the core material, it would be best to look at whether the core is solid or stranded.

Usually, solid wires are best for house cables and industrial use.

Thus, it is not advised to choose a solid core wire for your vehicle unless it is a baling cable. 

Since vehicle wiring must be flexible, it’s best to choose stranded wires for better performance and less damage.

Types of Automotive Wires

Here are the common type of vehicle wires that you can buy from any hardware shop.

GPT or Primary Wire

GPT stands for General Purpose Thermoplastic.

These wires consist of a multistranded wire core and flexible insulation, making them suitable for smaller areas.

However, they cannot endure outdoor conditions for longer and, thus, are best for interior applications.

Motor Wire

Although it is just like GPT wire, the motor wire uses much finer strands of copper.

Also, it can withstand higher voltages, for up to 600V, and endure temperatures up to 221 degrees Celcius. 

Battery Cable

This cable connects the battery to the vehicle’s other electrical components (starters, lights, etc.) and the ground.

The gauge of the battery cable is smaller and hence, which means it is thicker than other wires. 

Speaker Wire

Speaker wires are manufactured for low-voltage uses, like sending the audio signals from the stereo unit to the car’s speakers.

Remember to fix its positive and negative wires correctly with the stereo system, or the speakers will not work properly.  

Trailer Wire

Trailer wires work the same as GPT wires with special color scheming designed for the purpose.

Hence, you will see the same type of cable with green, brown, yellow, and white hues in the trailers. 


SXL wire is a bare copper wire with XLPE insulation on top.

TXL wire is stranded copper wire with the same cross-linked Polyethylene of XLPE insulation, while the GXL is a single conductor wire with thinner XLPE insulation. 

XLPE insulation makes the wire prone to abrasion, heat, and age better than the GPT wire.

Hence, in applications like heavy machines, SXL wire is preferred as it gives extra durability.

On the other hand, TXL has thinner insulation than GXL and SXL; thus, they are best used in racing cars, lowering their weight.

GXL wire is a cross between TXL and SXL regarding durability and thickness.

Can you use a house wire in a car?

Automotive wire bundle

Automotive wire bundle

In some cases, you can use the house wires in your car. However, it’s not recommended. 

For most cases, a car wire will require thick conductors as it will pass high current levels on 12V, unlike using 120 to 240V like the house.

Moreover, it will need a protective layer to withstand high temperatures and constant exposure to water, oil, and gasoline. 

Although the conductor type might be copper for both cases, still the cars will prefer stranded over solid for its flexibility.

Also, the wire may be just like the home appliances cord but with different labels and color schemes. 


Choosing the correct wire for any application will make or break the deal.

Hence, you must be vigilant while gathering the requirements, as it will shape your decision.

Moreover, consider other external factors that can influence the installation of your wire of choice. 

At Cloom, we thrive on giving you the best automotive wire harness so that your vehicle runs problem free for a longer time.

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