Model A Electrical Fire

[jmeckel]

This is a reminder of why it is a good idea to fuse the electrical system.
This car is listed on Mpls MN Craigslist, it is not mine, and I do not know the seller, just thought it would be a good reminder.

fire sale!!!!1928 FORD MODEL A COUPE WITH RUMBLE SEAT

The bad news is the coupe had a electrical fire while parked in my house garage.....

The good news is my house didn't burn down and the coupe sustained minor paint damage to the hood and outer firewall...........

Model A Electrical Fire.jpg

[Great Lakes Greg]

Nothing like a fire under a gas tank.

[Roadster62]

Maybe I'll let Dad's Roadster sit for another 30 years after all. Bob

[Bob C]

Probably one of those old reproduction terminal boxes with the screw
heads sticking out the back and shorting to the fire wall.

Bob

[Duffy1]

scary

[Phil]

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One fuse installed will keep this from happening! The one "upgrade" that is absolutely necessary.

[Tom Wesenberg]

It looks like it started at the terminal box and I was also thinking about the repro and screws touching the firewall.
If the key was left on and the coil overheated and caught fire, the fuse wouldn't have stopped it.
I wonder what the thing is at the rear of the head next to the firewall?

[Roadster62]

Thanks! That is something the "Electrically Clueless" like myself know nothing about. Fiber washers in the distributor, ground contacts here, its just overwhelming. I'll stick to body & paint work. Bob

Originally Posted by Bob C

Probably one of those old reproduction terminal boxes with the screw
heads sticking out the back and shorting to the fire wall.

Bob

[Kevin in NJ]

Would a fuse have prevented this fire?

Most fuses being used are too large for the size of the wire in the system. This would allow the wires to heat up beyond their flash point and still allow the fuse to be happy. If you wanted to properly protect your wires you would need to have a fuse for each circuit that was properly sized to the wire gauge.

In your house you have many things that get hot enough to start fires, but will not blow a fuse. Think about the number of house fires that are electrically related.

This incident is the main reason why you need to properly inspect your electrical system and I would also wonder if it was a reproduction terminal box. Quite frankly this is one of the few fires I have seen on a Model A. So they are really not very common.

Plus I would point out, the gas tank never caught fire. Further proving the system is fairly robust and not much of a safety hazard.

[Richard Wilson]

I saw this exact same type fire while on a Model A tour one time. A reproduction ignition switch had become loose in the dash panel and would rotate back and forth when the switch was turned off and on, or when the engine was running from vibration. Eventually, a terminal rubbed through the gas tank paint and grounded to the metal tank. In fact, it welded it's self to the tank forming a "dead" short. This caused every wire in the dash harness and engine to burn. Thankfully, the wire burned in two at the connector and he was able to get the fire out without much actual damage.

And yes, I had a roll of 12 gauge wire and connectors with me in my tool box and was able to make up a new wiring harness for the car in about an hour. The owner drove the car the rest of the day on the tour and back home.

A working safety fuse located at the starter would have prevented this fire. These can be purchased at any of the reproduction parts vendors.

[Lowell Fast]

What is the weakest fuse I can get by with?

[Tom Endy]

Originally Posted by Tom Wesenberg

It looks like it started at the terminal box and I was also thinking about the repro and screws touching the firewall.
If the key was left on and the coil overheated and caught fire, the fuse wouldn't have stopped it.
I wonder what the thing is at the rear of the head next to the firewall?

The fuse would have prevented the fire if it was removed when the car is left unattended. I make it a practice to pull the fuse and stand it on its head in one end of the fuse clip. Since my car has an indented fire wall I have to lift the hood to shut the fuel off. At the same time I pull the fuse.

I am fortunate that the fuse holder I have mounted on the starter is a very old one. The earlier ones have the fuse standing above the clip with enough space I can get my fingers under it to easily pull it out. The later ones are more difficult to remove.

Another trick is to put a tie wrap around the fuse to provide something to grab hold of to remove it.

Tom Endy

[Kurt in NJ]

Originally Posted by Lowell Fast

What is the weakest fuse I can get by with?

That depends on what you are trying to protect, and how often you are willing to put up with nuisance failures.

To protect wires the smallest wire in the circuit being protected determines the fuse rating.

To protect components it depends on the type of component, usually 120-150% of the components normal current draw ---the type of fuse,(slow blow, fast blow, normal) and whether it is a steady draw(lights) or a high starting current draw(motor) all are factors in fuse choice.

The location of a fuse in the circuit is important also---the typical fuse location of the fuse on the starter does NOT properly protect the lighting wiring when the car is driving, the lighting system has both the fuse rating + the charging system output avalible to the lighting harness ----say you have a 40 amp alternator, and a 30 amp fuse on the starter ---it is possible to have close to 70 amps (40 amp alternator probably won't make 40 amps hot) taken by the lighting harness before the 30 amp fuse blows ----with a generator it is the generator output (under 15)+ the fuse ----modifications from stock should change fuse choice for amperage and location.

[Tom Wesenberg]

Kurt brought up a good point. Since the lights/horn power is taken from the cutout output terminal, the generator output will still be going into the lights and horn circuits. If I was to add a fuse to my Model A I'd add a 20 amp fuse between the cutout output terminal and the lights/horn terminal.

[silversink]

also watch where the terminals are pointing in the junction box. mine shorted out on the conduit because I didn't pay attention to the terminals too close to the conduit

[Rowdy]

I once had smoke for the same location. It could have been prevented by instaiing the grommet on the ignition cable at the terminal box. Luckily I was nder the hood when it started smoking and the fllor boards were removed, All I had to do was turn the battery disconnect and the smoke stopped. Rod

[CarlG]

When I was 14 or 15 (in the mid 50's), on my first Model A (AA 280A) I managed to burn up the wiring harness and ampmeter. I got to re-wire the whole truck with a new harness from JC Whitney, ampmeter was a new Ford part I got from a local repair shop in SE Arizona where I lived. I think the harness cost me less than $5 (including postage), and the ampmeter was 25¢.

[Bob/Kansas City]

This kinda makes the point that a battery cutoff switch can be an important safeguard.

[39portlander]

Originally Posted by Bob/Kansas City

This kinda makes the point that a battery cutoff switch can be an important safeguard.

Got one on the 39 P/U and 77 F150. When I do find a ModelA, she'll get one too

[MrTube]

Originally Posted by 39portlander

Got one on the 39 P/U and 77 F150. When I do find a ModelA, she'll get one too

And yet I was always taught to NEVER connect near a battery as the arc could cause an explosion. Seems like that disconnect could be a very dangerous item under the right conditions?