Fuse & Breaker Options

kcav8or

kcav8or

Member
I'm nearing the point in my '31 Model A restoration where I need to start thinking about rewiring. I've already purchased replacement wiring harnesses, and I intend to protect my investment with fuses or breakers. I've seen a lot of posts that mention fuse sizes for different circuits, which is very helpful.

Is there a central fusebox option that I can install, or do people tend to install individual inline fuses in various places?
 
You're pretty much on your own. There is no standard fuse box sold for Model A use, other than the single fuse deal that mounts beside the starter switch, and which is rather controversial. Check the archives; there have been many detailed threads in recent years. As usual, you will find every level of opinion, starting from "Henry didn't use them, so they must be bad" to multi-fuse conglomerations like mine that are so complicated I'm not sure even I understand it.
 
kcav8or said:
Is there a central fusebox option that I can install, or do people tend to install individual inline fuses in various places?
Click to expand...

I hate to be clear as mud but the answer to your questions are yes and yes.

Those that decide to go the full fuse either purchase a fuse block with 6-8 fuses or put in inline fuses. It is easier to use inline fuses on a stock harness as you can just open the harness and put in a fuse holder. Use of a fuse block will necessitate a custom harness for the rerouting of wires to the block.

Keep in mind that fuses are to protect the wiring not the device on the end of the wire.
 
kcav8or said:
I'm nearing the point in my '31 Model A restoration where I need to start thinking about rewiring. I've already purchased replacement wiring harnesses, and I intend to protect my investment with fuses or breakers. I've seen a lot of posts that mention fuse sizes for different circuits, which is very helpful.

Is there a central fusebox option that I can install, or do people tend to install individual inline fuses in various places?
Click to expand...

I built a '30 and pondered same question many years ago. Read about ford wiring and about problems that were attributed to the old original cloth (? only) covered wire. I surmised that the problems (car fires and car in garage fires) were easily avoided by attention to routing wiring to avoid or improve sharp edges. Also, I found that 'original' looking wiring harness was now available which used the hard plastic/rubber coating of modern wire....inside original appearing materials. That made me feel that I could/would get the best of both worlds, i.e.-safety/original look. Because of problems that I encountered with starter switch, it made sense to install a 30 amp fuse at the switch..not at all bad looking either.
However, STILL being concerned about safety, I installed a heavy duty master kill switch in a very convenient location, so that while sitting...the first thing I do to energize is to turn master on , and of course, last thing that I do before leaving my seat...is to turn master off. I feel that as an extra added bonus (and it has paid off:)), in an emergency I shut her down in maybe two seconds...I'm old/slow, eh:D. Just used reason..your choice. Luck
 
steve s said:
. . . to multi-fuse conglomerations like mine that are so complicated I'm not sure even I understand it.
Click to expand...

Steve, welcome to the club! I carry a hand drawn wiring diagram with notes in one of my cars. The other is bone-stock with only a battery disconnect in the ground line.

kcav8or- A lot depends on what your electrical knowledge and skill level is. With the hundreds of guys who post here and who I know from clubs, I can count on one hand the number I would ever let do anything electrical, including changing a light bulb, on my car. I've seen some well intended fuse additions that look like a terrible rat's nest, some that used cheap chinese hardware that screams 'fire!' and a very few that were high quality work with the wires neatly dressed in loom and routed in a way that is difficult to discern from stock for the average under-hood inspector.
 
First off consider that there is not much of a fire hazard with the A electrical system. The car is just not known for fires when properly restored.

The fuse on the starter is a waste. It goes from the battery to the rest of the electrical system. So what happens when you are driving and have a short? The generator is going to keep pumping out electricity. Plus you allow the gen to have wild voltage since the battery is the voltage regulator. Not so good. Then the common fuse holder is a failure waiting to happen as they are not great quality and not made for vibration and outside positions. How would like to get stuck cause your fuse holder broke?

Next you must, MUST, understand that a fuse is designed to protect the wire from burning up. The fuse is sized to the smallest wire in the circuit. You can find charts on proper sizing online. Remember that a toaster is on a fused circuit, go look up how many house fires are from a toaster. A fuse is not going to stop a fire if the conditions are right.

If you are going to fuse the A then you need one on the gen wire, one on the battery wire. The fuse holder must be rated for engine compartment use.
Then be clever, you can get mini fuse holders and hide them in the junction box. I would bet an enterprising parts manufacturer could make up a repro junction box that looks normal on the outside, but has a fuse block and terminal posts.

If you properly put in new wiring then I would not worry too much about fuses.
 
I've got the standard fuse mount on both my "A's" and the heavy duty "kill" switches mounted under the starters. On the '31 roadster's generator {Delco-Remy from '35 Chevy truck} I also added a fuse mount
with one of the screws holding the Delco cut-out on the Genny. It is for in case of a headlight short.:eek: And, it looks neat!:p I got the idea from an old 20s-30s Western-Auto catalog that shows a double fuse mount attached to the cut-out on a Model-A generator.;)

Bob-A:D
 
While on the Glidden Tour some years ago my 31 fuse became dislodged( from removing it while long term parking). The engine died immediately upon RPM drop below cut in speed. Took 5 minutes to diagnose and repair. The fuse is the conventional one sold by vendors on the starter. BUT, that fuse does nothing to protect the starter from a current draw. So, I installed a battery shut off that also is sold by vendors. However, I kept the Neg battery cable direct to the starter terminal and removed the small braided ground cable from the cross member and ran a new 24 " to the frame. So the positive is disconnected. This protects the circuit from shorting if a tool is dropped or the brake pedal strips the insulation etc. The worst that can happen is I complete the circuit, but no short out.
 
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