I've installed a 12" fusible link as a replacement for a fusible link on the line that charges the battery from the alternator. I showed the OEM part to the guy at the parts store and he gave me a 12" piece of fusible link wire. I also showed him the old link (about 6" long). He told me not to cut it as length matters in these cases. I've since heard that fusible links should not be longer than 9". Is the one I installed still effective? It comes out of the package at 12"
According to this Fusible link FAQ:
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.
Ensure the size/length you put back in is the size/length you took out. Also, as I've highlighted, a new fusible link will do you no good if you have not figured out the reason for the old one to go bad in the first place.