We get many questions about fusible link wire. Below are some that we get most frequently.
What is a Fusible Link?
A fusible link is a short piece of insulated low-voltage cable within an automotive wiring harness that is designed to protect the harness in applications where a fuse is unsuitable. In an extreme current overload situation, the conductor within the link is melted while the ensuing flame and spark is contained within the link's insulation.
What are the ratings for fusible links?
Fusible links are not rated in amps like fuses because each installation is unique and designed to meet specific circuit protection requirements.
What size replacement fusible link should be used?
The automotive service industry recommends using the same gauge and length as the blown fusible link after the cause of failure is corrected. There is some specific engineering that goes into determining what gauge and length of fusible link wire is used. If your application is otherwise stock, it is best to directly replace your fusible link wire with one of the same specifications. However it is important to determine what caused the original one to fail so you don’t burn it out again.
If your application is not stock, you can do some more research to see if you can determine the appropriate fusible link wire to use. Although we don’t necessarily recommend this course of action, another option is to use a Maxi Fuse or Breaker in place of the fusible link wire. Generally people go with a fuse or breaker rated at about 10% greater than the output of the alternator - assuming the wiring is sufficient for that amperage. But proceed with caution as fuses/breakers are not necessarily a direct replacement for fusible links, and could lead to damage to the vehicle, including a fire.
We are sorry but we cannot give specific recommendations regarding which fusible link wire to use other than to go with the OEM spec.
Can a blown fusible link be replaced with a MAXI fuse?
While "MAXI" fuses have replaced most factory-installed fusible links in late model vehicles, they have different performance characteristics than fusible links and should not be used to replace them unless specifically authorized by a vehicle factory service bulletin. Fusible links continue to be used in most starting circuit applications.
Can Type SXL primary wire be used to replace a fusible link?
SXL wire would work as an emergency replacement, but it would not have the required "Fusible Link" markings and the insulation would not be designed to contain flame and spark in the event of a circuit failure.
What size fusible link should be used in a new installation?
The suitability of a fusible link in a new application can be determined only by a qualified harness engineer with full knowledge of the circuit protection requirements, the installation and operating conditions, and the safety and liability aspects. We cannot make specific recommendations.
Are there any general guidelines for choosing a suitable fusible link?
Typically, a given harness segment is protected by fusible link that is four gauge numbers smaller. A 14-gauge wire would be protected by an 18-gauge fusible link. A 6-gauge wire would be protected by a 10-gauge link, and so on. Odd number wire gauge sizes like 19, 15, 13 and 11 are counted when sizing a link. The length of a fusible link should not exceed 9".
Can a fusible link be used to replace a fuse that blows frequently?
In general, a fusible link should never be used to replace an automotive fuse unless authorized by a vehicle factory service bulletin. Safety and liability issues are involved.
Where can I find more technical information on automotive fusible links?
Specifications relating to conductors, insulation, wire size, length, location termination, identification and testing are spelled out in SAE Specification J156, The Society of Automotive Engineers' web address is www.sae.org.