Im going to run 2 seperate wires to my solenoid with in line fuses. 1 for a tach and the other for the cig lighter. What amp fuses should i use, I dont want to go to high.

Its a 75 F100 if that matters.

 

What size wire are you going to run? And what are you going to plug into the cigarette lighter?

The fuse protects the wire.

The wire supplies the power needed.

So, the tach is not going to use much, but maybe later you will add some more stuff to that wire? If you run a 16 gauge wire to the tach, I would put a 10 amp fuse with it.

If you run a 16 gauge wire to the lighter, then you will also be limited to a 10 amp fuse, and 10 amps to whatever you plug into the lighter.

If you want to run more power to the cigarette lighter, then here is a general idea of what it will take.

16 gauge wire= 10 amp fuse
14 guage wire= 15 amp fuse
12 gauge wire= 20 amp fuse
10 gauge wire= 30 amp fuse

 

Cell charger and one of those plugs that let you play your i-pod over the radio station. I have 16 gage wire, but could always get bigger wire.

What would happen if I put a bigger amp fuse than I need in?

 

Don't overfuse. Fuses protect wires from melting or starting a fire in the event of a short or overload. When you overfuse the wires, in the event of a problem, the fuse may fail to blow. Its best to match your fuse to your wire size.

Steve

 

Yes, if you have a large fuse on the supply side, and a large load on the other end, and a small wire inbetween, the wire can overheat.

The specs I listed in the previous post are conservative. You could probably run more than 10 amps on a 16 gauge wire. But we are not on a assembly line producing millions of vehicles and spending millions of dollars on copper wire, so we can afford a little bit larger wire. Being conservative on the wire size means less voltage drop through the wire, and less wire heating.