The wiring kit I am using has an 8 gauge wire which is the main power source from the battery to the fuse box and they say to protect this wire with a fusible link but do not give a size. The largest size I can find is a 12 gauge , will this work or do I need to keep looking? Thanks
The wiring kit I am using has an 8 gauge wire which is the main power source from the battery to the fuse box and they say to protect this wire with a fusible link but do not give a size. The largest size I can find is a 12 gauge , will this work or do I need to keep looking? Thanks
typically the FL should be +4 ga over the base wire.. so if you are 8ga, +4 = 12ga.
I am running 2ga (160amps), and ended up with a heavy stereo style fuse (175a) inline instead cause I couldn't find the right FL size either. I like the idea of the fuse anyhow, and wish I had used a resettable version, vs replaceable.. (one less reason to jack the truck up)
The other approach (a better one) is to break the fuse box loads up onto two (or more) mains, each served by appropriately sized FL's. Then you only lose those circuits if one blows. Not uncommon for modern cars to have 2 or 3 parallel FL's feeding the fusebox. Usually you want lights to be on their own feed all the way back to the battery, so you don't lose lights on a dark night while rounding a corner and your A/C takes out a bunch of circuits.
Fusible links are one time circuit protection, once burnt they are toast (). In my bias one sided prejudiced opinion they are obsolete Neanderthal technology and must be cheap or the manufactures won’t be using them. Use automatic (bi-metallic strip) resetting circuit breakers, that way if the lights short out they will come back on until the short/overload turns them out again. Flashing/flickering headlights are better then no lights at all, I think.
Fusible links are one time circuit protection, once burnt they are toast (). In my bias one sided prejudiced opinion they are obsolete Neanderthal technology and must be cheap or the manufactures won’t be using them. Use automatic (bi-metallic strip) resetting circuit breakers, that way if the lights short out they will come back on until the short/overload turns them out again. Flashing/flickering headlights are better then no lights at all, I think.
There is both a flaw, and wisdom, in your logic. First, circuit breakers must be cheaper, because that's what Henry used on Bonus Built trucks! But you are correct, they are the correct "final link" between the battery and lights. Usually a fusible link feeds several breakers or fuses that will blow before the FL. Fusible links are the "last chance" to keep a whole harness from frying from a catastrophe. I think in modern cars their main purpose is to prevent a fire in an accident, when an entire harness might get crushed between two pieces of sheet metal.
The reason for the "fuseable link" you are talking about is if you have a BIG short someplace, it will sever the link to the alternator. You want this so th ealternator doesn't "run away" trying to supply th edemand caused by the short and in th eprocess send those excessive amps to all of your electrical items.
Now if I read your question correctly, you are concerned because the power wire you have is 8 AWG and the wire on the "Fuseable Link" holder is only 12 AWG, right?
With wires this big, I would be tempted, as previously mentioned, to use a circuit breaker instead. I say this not because they are cheaper, or more effective (although as Old mentioned they are more convenient because they reset), but because they are physically configured with a holding bracket and connected with two lugs rather than wire splice. So, you can put connectors on the ends of your 8 AWG feed and connect it to the CB safely.
You should have two of these links: one on the flow path coming from the generator/alternator; and one on the wire providing power from the battery - which comes down from the "BATT" lug on the starter solenoid. The reason is if you have a "Discharge" situation (whatever it might be caused by) the power is going to start to flow from the battery, not the generator/alternator.
Ross elluded to a second key point, and that is that it would be prudent a run two seperate fuse blocks for protection as well.
One fuse block is for "HOT" (allways powered) items like headlights, running lights, brake lights, ignition switch, horn, courtesy lights, glove box light (if installed), and cigarette lighter.
The second fuse block is for "SWITCHED" items that you power when you turn on the ignition switch: ignition, radio, heater, wipers, gauges, and any other accessories you may have installed (ie, electric fule pump, etc.)
NAPA sells a premium fuse block for about $20 that i recommend. It is P/N BK7823208. It is a two bar, fuse type, distribution BUS. It has two distribution bars - one of 7 fuses another of 3 fuses. The two bars can be linked with a jumper wire to power all ten spots from one input.
The reason I bring up the two positions, is if you are forced to keep 6 volt accessories (like a 51/52 Magic Aire Heater where no 12 volt motors are made) you can use the 3 fuse side to distribute 6 volt power (converted from a "Vol-ta-drop") and the other 7 positions can be fed with from the 12 volt supply.
One more thought. We can talk all day long on configuration or types of components, theory and philosophy - how they install and how easy they are to reset.
But remember this: if you have a situation that causes a 175 amp (or for that matter a 75 amp) fuse, fuseable link, or circuit breaker to activate, IT'S TIME TO VERY CAREFULLY TAKE THE KEY OUT OF THE IGNITION, TOW THE TRUCK HOME, DISCONNECT BOTH BATTERY CABLES, AND FIND THE PROBLEM BEFORE YOU TRY TO RESET ANYTHING.
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). In my bias one sided prejudiced opinion they are obsolete Neanderthal technology and must be cheap or the manufactures won’t be using them. Use automatic (bi-metallic strip) resetting circuit breakers, that way if the lights short out they will come back on until the short/overload turns them out again. Flashing/flickering headlights are better then no lights at all, I think. 
But you are correct, they are the correct "final link" between the battery and lights. Usually a fusible link feeds several breakers or fuses that will blow before the FL. Fusible links are the "last chance" to keep a whole harness from frying from a catastrophe. I think in modern cars their main purpose is to prevent a fire in an accident, when an entire harness might get crushed between two pieces of sheet metal.
