A Comparison Between Two Safety Points in Automotive Electronics

We’ll compare fusible link vs. fuse in this article. 

Although built using rigorously tested cables and harnesses, automotive wiring systems are not immune to electrical faults. 

Sudden surges or shorts can affect critical sensors, damage components, or even cause significant shorting in other areas that can start fires. 

So the system needs safety points. And the two critical ones are fusible links and fuses. Let’s compare fusible links vs. fuses to see how they function and differ.

What Are Fusible Links?

In general, fusible links are mechanical or electrical safety devices. 

The former comprises two metal strips soldered using a fusible alloy that melts at specific temperatures. 

So when the heat levels increase, the alloy separates the two pieces, creating a separation (discontinuity).

Here, we are more interested in the electrical fusible link because it is typical in automotive applications. 

It consists of a short piece of low-voltage insulated cable that is usually 2-4 AWG wire sizes thinner than the cables it connects. 

For instance, you can use a 12 AWG fusible link to protect an 8 AWG wiring line.

The purpose of this thin wire is to be the sacrificial lamb in case of an electrical fault, overload, or short circuit. 

Since it cannot handle the excess current, the wire will burn out, cutting electric current flow and preventing further disaster.

And if the wire heats to its melting point, the hot wire can be disastrous because it can ignite the insulation around it.

 So fusible links must have special material insulation that can withstand high temperatures. 

This fire-resistant insulation usually feels more rubbery than materials in other cables.

How To Locate Fusible Links

Cars and trucks have several fusible links, and they usually protect high-amperage circuit lines, such as from the battery to the starter motor. 

You can also find them near the alternator and battery in the engine bay.

Wires evacuating power from a car’s alternator

If the fusible link between the battery and starter motor burns, the vehicle can’t start because power won’t reach the starter.

 It might be inconvenient, but the link will protect your car from fires or other far-damaging electrical issues.

So if the wire burns, the first thing you need to do is locate it. 

As stated earlier, one way of identifying this link is through its rubbery insulation feel.

 And it should be short. Most have “fusible link” tags, so you don’t have to struggle to find them.

But the tag might be absent in older vehicles.

 So look for tiny wires near the battery or firewall, which are thinner than the wiring harnesses connecting them. 

In newer cars, look for these wires in the fuse box.

A car’s fuse box

What Are Fuses?

Fuses operate like fusible links. 

They have a thin wire that heats and melts to create discontinuity if there is a surge or electrical short. 

But fuses typically handle less current. 

So while fusible links safeguard high electrical current sources and parts or delicate harnesses, fuses handle regular car components.

Car Fuse Generations

Car fuses began as glass tubes with metal-capped end terminals and thin metal strips inside the cylinder connecting the metal ends.

Glass tube fuses

Bosch fuses had the same cylindrical shape but replaced the glass tube with solid ceramic and an external metal strip.