Im working on a self contained auxiliary fuse box for my F150 that will contain all my aftermarket circuits powered by fuses and relays. How ever Ive been looking at the main power wire for this box, I am currently looking at running a 10ga power wire as I can run 7ft of 10ga wire for a 40A circuit and be fine.

The current load I figured on my auxiliary fuse box is 35.96A which I feel is cutting it close to the 40A circuit. But if I go ahead with adding two more circuits for four more auxiliary lights at 400w for the set of four it would raise my auxiliary fuse box to a total of 67.21A which is way too much for a 10ga wire.

Problem I have is I could run a 6ga battery cable as my power supply that would be good for 70A but the bussed fuse terminals I have I do not believe would be capable of crimping around a 6ga cable. I think a 10ga cable would be about the largest I could go. Then I have the problem of a ATC/ATO fuse has a max size of 40A I would have to go to a Maxi fuse for 70A which I don't think there is a nice inline holder.

Im just curious what are my options to do this right when I am limited on how large a wire will fit the bussed fuse terminals.

I thought about running a second 10ga power wire and run a 40A fuse in each wire and connect the wires on each ends of the bussed fuse terminal. I just don't like this option as I can just see one wire having a problem and the fuse popping then all current being forced through the other power wire and popping that fuse. That would be bad for me as this auxiliary fuse box will be powering my headlight circuits via relays, my KC driving lights via another relay, and a couple fuses for my CB and CB Amp. Another relay I was going to use for my choke to use the stator wire as a trigger to send 12v to my aftermarket 4V carb. But I am looking to use that as a AC triggered relay to supply ground to the fuel injection system I am going to run instead. This leaves me two relays to add a couple more relay operated circuits along with 3 unused fuses two of which would be used for the two relays with one final fuse for another add on circuit I haven't decided on.

So I would like to do this auxiliary fuse box right and be wired properly for any future circuits I may or may not add. I don't want to do this a third time.

 

Does this aux fuse box have a total load rating? Keep that in mind also. I would run parallel 10 gauge conductors, but do not use double fuses, use one single larger fuse. Parallel conductors are used all the time by power companies, electricians, and even Ford used parallel conductors on some of their circuits. You already have the wire,, the crimps, and you can stack them on your termination points.

 

I never saw a load rating for the box I got all the specs listed was that it has 6 fuses and 6 relays. I'll double check but I dont remember a rating being give for the box itself. I know the box came with individual fuse terminals and i bought a cheap bussed fuse block off ebay to rob the fuse bus bar for this out of.

So run a larger gauge single wire to the fuse then run double 10ga wires after the fuse basically I take it?

I'll have to look at the maxi fuse holders see if I cound find one that doesnt look weird.

 

Run double wires the whole way, or run a single and then a double like you said, however you wanted to do it. Besides capacity of the wiring, you do have physical considerations also like you mentioned, so whatever your needs are, and what you happen to have that would work.

Ford used parallel conductors on their famous fire starter 2G alternators, and they also use parallel conductors with double fusible links to feed the glowplugs on my diesel pickup.

 

I will have to decide. I bought over 100ft of wire in 16 and 20 ga for most of my fuse box wiring. But I haven't purchased any main power wires just yet. I figured I could start using 16 and 20 ga wire for wiring up from the fuses to the relays internally.

I thought of doing fusible links as the company I bought my SLX wire from has quality fusible links but I decided against that as then I would be stuck without lights and a CB. At least with a fuse I could pop the fuse out and throw a new one in.

 

I am sort of a proponent of fusible links. The factory still uses them, even with all these maxi and mega fuses under the hood of modern cars. They are small, weatherproof and cheap. And they are very robust, a little more robust than a fuse. But they are there just to protect the wiring and keep it from catching fire in case of a catastrophic failure, say from a accident. A fuse would blow quicker and possibly protect your actual device a little better than a fusible link. So like many things, there is no one perfect solution.

 

Maybe I should go fusible link. 9nly thing with this route is the company I bought my wire from says to take your fusible link 2 gauges smaller than your primary. So if I run 6 gauge from batter hot to a 10 gauge fusible link (unless they mean two gauges number wise which would be 8ga which they dont carry) I would have to solder two 10gauge wires to the 10 gauge link.

I guess I could buy that lead barrel crimp like factory uses for multiple wires from one. Maybe add a little solder to it to ensure a good connection.

I might just get the 6ga wire since I need it anyways for my charge wire from alternator (unless I go with 130A then I'll need probably a 4ga) and see if the 6ga will attach to my bussed fuse terminal.

 

Again, you have the electrical part of the equation, and then the physical part and actually being able to buy what you need. That might be why the factory used two fusible links and two 10 gauge wires to feed my glowplugs. But even the factory changed that later on to one large wire, but I do not know how they protected that wire. These glowplugs can pull about 30 amps each, and there are 8 of them, so it's got right much draw on it when they are glowing. They had a disconnect plug near the pass side valve cover to disconnect these wires when the engine is pulled, and that plug is famous for melting. Just like the famous melting plug on the 80's and 90's headlight switch, even the factory had their design problems. But they had to juggle costs too, we can over build our stuff.

 

Of course. I dont mind over building. I just have limitations in some aspects.

Like right now I found out the 95A 3G alternator I wanted to run doesnt come in a 8" pivot mount just 7". Only the 130A came with the 8" pivot mount option. So I have to decide if I can get proper fitment with the 7" 95A or go with the 130A version then restrict the 130A down by running the same 6ga and 125A fuse. Not like a single V belt will spin a full fielded alternator in the first place to burn it up without slipping or throwing the belt.

So it's a simmilar problem to my auxiliary fuse box having limitations as well.

All in all whole truck shouldnt pull over 80A in the end so everything I am accounting for is over kill outside of the 95A alternator i would have preferred to run.

My auxiliary fuse box might get put on a diet cause I've been hearing the 6" daylighters with the LED option puts out more light than my 6" 100W halogen driving lights. If that's true then I'll upgrade to LED and cut my power requirements for the auxiliary fuse box.

 

LED bulbs are great for lowering power requirements. I have never checked into it very closely, but supposedly they make a special regulator to fit the 3G that brings it online slower than the factory regulator, making it a little bit more gentle on a single v-belt. Here we go again, why would you want a alternator who's full output you can't really use, but you mentioned physical fitment issues, so you do what you have to do to make it work.

 

Well my thing is I found out the 8" pivot mount is what 80-86 trucks need for the V8`s as the alternator/airpump bracket would not allow the 7" pivot mount alternator fit properly. Something to do with the shortness not allowing the alternator to swing towards the crank as much as the 8" pivot mount.

So I was looking for the 8" pivot mount but I had an alternator shop tell me today that the 95A 3G never came in anything but the standard 7" pivot mount that there was no 8" pivot mount that was only an option on the 130A 3G alternator. If A 7" pivot mount would fit my bracket and allow me to use the OE sized belt then yes I would just get it anyways. But my main issue is I want to retain the OE length belt to make life easier on me. If the belt ever was thrown off due to slippage and I lost the belt I wouldn't know what size it is but if its the OE size then I just get a belt for my application.

Realistically I would love to just have the 95A 3G cause it would fit my bill nicely. But what I was told today I cant get it in the right sized pivot mount. I know it says some 7" pivot mounts will work in place of the 8" pivot mount but it requires a tensioner arm that can be adjusted to the narrower bolt pattern.

On the regulator there is two that I found, there is one with a 2 second and one with a 10 second delay. I actually have the 10 second delay one I found in my shopping cart to purchase it when I purchase the alternator. Just still on the fence if I want to get the 95A and take a risk and hope it will pivot enough or just go with what is known to work which requires going up to the 130A. I also could run a double V belt by changing the crank pulley out for one with an extra sheave but then I would have to relocate my ps pulley forward and I would also lose my AC which I do not want to do.

Even at DB Electrical the 95A 3G is $65 and the 130A 3G is $80. DB Electrical cant even tell me what the ear spacing on the 95A one they offer is, they don't have that information and apparently it was too hard for them to walk into the stock room and pull said alternator in question and measure it.

On the LED, I might go ahead and do the swap its just $400 for two daylighters in LED with or without the wiring kit. I don't need the wiring kit I don't use it anyways, but the Apollos were $60 for two individual lights while the kit was $175. Dunno why their individual housings are the same price.

 

Don't know how you are at fabrication. Here's a link with some possible ideas to try and adapt the smaller alternator.

https://alternatorparts.com/alternator-brackets.html

 

FYI, 10 AWG is rated for 30 amps, not 40. The problem with running parallel #10 wires is if the connection loosens on one of them over time. Just go to a place like Home Depot and have them cut #8 to the length you need. Depending on the temperature rating of the #8 it will handle between 40 and 55 amps.

 

I will keep that in mind. Im going to go measure my alternator right now and verify it is the 8" pivot I believe it is cause that's what all sources say for v belt mounts to use the 8" pivot mount as the 7" pivot mount is for serpentine belts. But I was thinking last night and that '82 F150 I built with a 5.0 coyote the old 302 that came out I kept the alternator and I measured it like 3 years ago and it was not 8" it was 7". Maybe I am going off faulty information or maybe a 7" pivot will work but then again this is also a 1G alternator which I think has a smaller case than the 3G but its something for me to check once the rain lets up.

amperage for wire is dependent on the length of said wire. Its why you up the size for longer runs of wire and you can lower the size for shorter runs.

Using a wire calculator that makes it easier than going about it via math it states for a 10ga wire at 40A the length has to be less than 7ft in length. Doubling up the wire with two 10ga wires will make the effective gauge 7ga which would be good for 40A up to 15ft in length.

Its no different than the charge wire from the 3G alternator to my solenoid the length of wire is not going to exceed 3 feet. 6Ga at 125A is good for up to 5 1/2 feet.

As far as going to home depot goes, first off I would never buy wire from a home improvement store for automotive applications, especially under hood where its exposed to heat and chemicals. Secondly it isn't a question about running a larger gauge wire, I would run a 6ga wire if I could. But my limitations is on the fuse box I have which the bussed fuse pin connectors would never be able to fit a 6ga power wire. 10ga I believe is about the largest I could go, so it is more of a mechanical limitation than me not wanting to run a single 6ga wire. The fact is currently I don't need a 6Ga power feed wire as my components are drawing no more than 35A as it is now. A single 10ga would suffice, but I have multiple circuits empty in the fuse box and would like to future proof for any mods I might do in the future. Like one of the fuses in the fuse box would be for the battery hot for my Dakota digital RTX gauges if they are ever offered for 80 - 86 trucks. So I would have that wire already pre made in the box ready to go. The two auxiliary light relays that I may use for four more roll bar mounted auxiliary lights would be pre wired as well in the off chance I decide to use them in the future as well. I don't want to have to rip my woven mesh loom apart to add circuits when I can future proof my fuse box to be capable of any planned electric upgrades.

 

That's NEC code for wiring, and it's what I usually go by also. But Ford never did, they used a 10 gauge wire on their 60 amp alternators all the time. Like he mentioned the distance is a factor, and the ambient conditions. It's all about heat dissipation of the wire, which is why there are different NEC charts whether you have 3 conductors crowded in a conduit, or your conductors are in open air. You would think you would need to de rate the wire since it's under the hot hood around a heat generating combustion engine, but I guess they figured it somehow. And they are trying to save wherever they could when they built these things.