The Ford Barn

Kevin in NJ · 09-08-2013, 08:45 AM

Think again!!

My brother an I were discussing this and it was brought up late in another thread so I am bringing out as a new thread.

Here is what we believe:

The fuse that is placed at the starter is a fuse between the battery and the body does not protect the car when the engine is running.

When the engine is running the generator is providing the electricity and is on the body side of the fuse.

So if you have a short circuit in the body wiring the fuse will only take the battery out of the circuit. The generator will continue suppling electricity.

SO,
The fuse that is placed at the starter is just providing a false peace of mind.

There are other fundamental problems with this single fuse.
Usually it is way too big for the wires it is supposed to protect and it is still possible to get a fire with something less then a short circuit. Keep in mind your toaster can start a fire without blowing the breaker. A thin wire with too large a fuse can get red hot.

To top it off, the fuse is a common fail point that will strand you or cause subtle run issues as it gets a high resistance. The fuse holders sometimes fail or get corrosion as they are really not intended to be in the elements.

If you really wish to protect your car then you need to consider a fuse at the battery and at the cut out for the main power feeds and then a separate set of fuses for each circuit in the terminal box.
Maybe one of the venders will be reading this and come up with a custom solution that can look original till you take the terminal box cover off.

The fuses are to sized for the type of wire they are to protect, not the expected amount of current needed by the devices.

The best protection is a well inspected good set of wiring. The Model A does not have much to catch fire and is not really prone to fires.

Anyway, I hope this is something to chew on (in a positive way) for the group.

09-08-2013, 08:45 AM	#1
Kevin in NJ Senior Member Join Date: May 2010 Location: South East NJ Posts: 3,398	So you think the fuse on the starter will protect you? Think again!! My brother an I were discussing this and it was brought up late in another thread so I am bringing out as a new thread. Here is what we believe: The fuse that is placed at the starter is a fuse between the battery and the body does not protect the car when the engine is running. When the engine is running the generator is providing the electricity and is on the body side of the fuse. So if you have a short circuit in the body wiring the fuse will only take the battery out of the circuit. The generator will continue suppling electricity. SO, The fuse that is placed at the starter is just providing a false peace of mind. There are other fundamental problems with this single fuse. Usually it is way too big for the wires it is supposed to protect and it is still possible to get a fire with something less then a short circuit. Keep in mind your toaster can start a fire without blowing the breaker. A thin wire with too large a fuse can get red hot. To top it off, the fuse is a common fail point that will strand you or cause subtle run issues as it gets a high resistance. The fuse holders sometimes fail or get corrosion as they are really not intended to be in the elements. If you really wish to protect your car then you need to consider a fuse at the battery and at the cut out for the main power feeds and then a separate set of fuses for each circuit in the terminal box. Maybe one of the venders will be reading this and come up with a custom solution that can look original till you take the terminal box cover off. The fuses are to sized for the type of wire they are to protect, not the expected amount of current needed by the devices. The best protection is a well inspected good set of wiring. The Model A does not have much to catch fire and is not really prone to fires. Anyway, I hope this is something to chew on (in a positive way) for the group.