Hi, I have the typical 10ga wire from the battery to a 40amp relay. Today i was at a muffler shop and the guy see the hotwire with a 20amp fuse.

He told me the fuse before the relay is against the purpose of the hotwire. Is that true? i need to run the 10ga from the battery to the relay straight?

 

you should be running a 40a fuse or higher, what ever the rating on the fuse it will support that amperage before it pops

Honestly I dont typically use fuses in this situation but I make sure theres no way for the hot wire to short out. It would be recomended to use a fuse just make sure its the proper size, I would go with either a 40A or 50A

 

^^^^ What he said ^^^^

every relay should be protected by a fuse.

 

Thanks guys, 40amp fuse already in place.

 

The 20amp is for the original fuel pump wiring. That wire is no longer under the load from the pump once you put a relay in with direct battery power.