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Guys,

I'm looking ahead to wiring my '49 Chevy 3800. I am planning to build my own harness. I am converted to 12v. It will be basic. I am only adding 3 things that the factory didn't have. A basic stereo system, fog lamps, and electric wipers. My truck has an aftermarket turn signal which I plan to reuse. Keeping things basic. Although I would like to have a circuit or 2 left over just in case. I believe my stereo set up will allow for me to use an inline fuse, but would prefer one at the panel if space allows. I have a spot I want to hide it, so space is a limiting factor. I think I have room for a panel with 8 fused circuits.

So here is my question...Which circuits on the truck need to be fused? I plan to use relays on the headlights and fog lamps. I've seen the difference they make and I will depart from stock for that simple upgrade from a safety standpoint.

At a minimum, I will need fuses in the panel for.......

My advice is to fuse all circuits. A shorted wire of any size, going anywhere, can case a total loss. Do you have wiring in your home not protected by fuses or circuit breakers?

Beltfed, agreed. I guess to clarify my question, given the 3 items I am adding to the truck in OP, how many circuits will be necessary. I know headlamps, fogs, horn, turn, tail, wipers, hazzards, stereo, dash will need to be fused. What I am trying to accomplish is to place a fuse panel in an original component so as not to detract from the original look. But finding modern fuse panels that fit the size are a challenge. I plan to fuse the radio by itself.

I am attempting to glean what has to or should be fused through a panel and what can be fused through individual fusible links or add a fuses....

We’ve seen fuse blocks put just about everywhere, from inside a voltage regulator housing to glove box, you name it. If space is an issue, could you not mount two fuse blocks? One for engine compartment and one for interior? To be honest, anyone who knows about old cars will spot your upgrades anyway. If nothing else, your battery size will give it away, or the brake booster and an alternator instead of a generator. Are you going with cloth covered wire instead of a cross link poly type wire? And so on...
Look at the “DelCity” website. They have some interesting fuse blocks and other items which may help you reach your goal. Good luck.

There are all sorts of fuse blocks available on Ebay, and the ones for the modern rectangular plastic fuses can be fitted into some pretty imaginative places. "More is better" is always the case where electrical circuits are concerned, so install a fuse block with more circuits available than you think you might need- - - -you'll find a use for those "unnecessary" slots pretty soon! I also install one of the big master fuses like a 40 amp or larger in the supply line to the fuse block. My Honda Gold Wing got rewired that way, and I'm running out of fuse circuits already!
Jerry

Which "should be" on fuse block and which should be inline? makes no difference. Try to do all in fuse block. If not, add an inline. Normally inline's are used in old trucks as an "add on" safety or added component. You are starting from scratch, so all in one box is a good goal.
You will use fusible links for the main hot feeds to fuse box, ignition switch, headlight switch, foot start. (not sure about 1949 system). Basically a fusible linked hot wire from battery positive to ignition switch, then ignition switch to hot bar on fuse panel. That energizes one side of fuse contacts when ignition is on. The other sides of fuse holder contacts go to various switches and components. Some components could have their own fuse ( I.E. radio, headlight switch). You may want some circuits to be hot all the time and not be turned on by ignition switch. That would be a fusible linked wire direct to a separate section of fuse hot bar.
As said, everything needs fused or fusible link. You can buy a donor fuse box from any vehicle that has the size you need and quantity of circuits or a new box. The mini fuse/ATO box will be the smallest. Don't let "hiding" the box control your life. Just mount it in a practical place for wiring and access. you are updating as per normal people, you are not building a museum piece.

Fusible links are just a special wire, sized to be four wire sizes smaller than the wire they are protecting. Like 16 ga fusible link protects a 12 ga wire. Available at all the FLAPS. Place them at the battery end of a hot wire.

I've never seen a fusible link that will carry the current draw of a starter. Using a fuse link on a stomp start is literally a "non-starter"!
LOL!
Jerry

Just to clarify. I do not mean a battery cable in any of my comments. I'm talking feed wire. Just giving general wiring opinion/info, as applicable. Sorry for the confusion.

Good points guys. I am going to use the voltage regulator housing as the placement for the new panel. I know seeing the alternator will be a dead giveaway that it is no longer 6v, but I think it will look better than having a plastic box on the firewall, or a panel under the dash where it is hard to get to in the event that one is blown. I know about extra circuits. I also have a jeep. But I don't think there will be any additional items added to this build beyond what is already mentioned. At least I cannot envision any. Not to say it won't ever happen, but if it does, I'll address that. I feel like that with an 8 circuit box, I'll have everything covered with one fused circuit to spare. There really aren't many circuits on these old trucks.

I guess I'm looking for some feedback on which circuits should be in that fuse panel. I have found a 6 circuit fuse panel that will work easy in that space, as well as an 8 circuit that I *think* will work with a little modification. Basically trimming the mounting base. I'm a firm believer in using fuses.

Planning to run power to relays on HI/Lo headlamps and fog lamps through a common buss. Again, going to be obviously not original, but safety over originality in this case.

I'm also trying to determine what gauge wires each component needs. I know 8/10ga for ignition power supply. Going to attempt to retrofit some modern gauges into the original cluster and move away from the volt-meter and use an ammeter (or is it the other way around)

Using LED bulbs for dash and turn/tail. My fingers are crossed that I can source some that are in warm white color to mimic the original under dash. I just like their durability, low power draw, etc.

I may be overthinking things a touch. I just want it to be thorough and not have to redo something after the fact.

I would suggest using a fuse-linked 10 gauge wire to supply the power to the headlight relays, and fuse the headlight switch with a 10 amp circuit or so, just enough to carry the trigger signal for the relay coils. That will eliminate one heavy current draw circuit under the dash. The dimmer switch will also be spared the load of carrying full headlight current that way, as it will become part of the relay energizing circuit. If you use a voltmeter instead of an ammeter, that's another heavy current circuit that's eliminated, although I consider that modification to be foolish and unnecessary when a simple shunt at the ammeter accomplishes the same result.
Jerry

When I built my wiring harness for the '51, I kept all of the circuits the same as original, with the following exceptions. The turn signals are fused through the original stop light fuse on the firewall. I added a 5 circuit fuse block under the cover of the voltage regulator. I used one circuit for each of the following: radio, cigarette lighter, heater, wipers and one spare for future expansion.