I recently bought My first model T a 26 touring, (Without a Fuse in yellow battery wire)which I didn't know. first night I turned the lights on and off a couple of times time checking out the bright and Dim function and then all of a sudden when I switched back to dim a shower of sparks shot out from the switch assembly under the dash, a little unnerving, I switched it back to off position I felt the wires going to the switch and they were not warm, But I smelled burnt plastic, The switch on My 26 is a reproduction part sold by several of the T supply houses, this one has crimped taps that hold the switch together as opposed to original which is held together by three pins in a non plastic switch body that mates with switch case and can be easily opened to clean the switch. I have a original Ford Switch and compared the two, the original has a solid positive feel with firm positive stops, even though it is close to a hundred years old, reproduction switch has a stiff action and the stops are spongy allowing the switch contacts to apparently go past the stops and short out against the case ? So I plan on at least two in line fuses one main, and one in a separate line to the distributor / coil which by passes main fuse, since with out a mag if the main fuse blew going down the road the engine would stop, I will also install a disconnect on the negative battery post, nice to be able to easily disconnect the battery for repairs, storage safety & theft prevention. I have had one on my tractor for years, the reproduction switch looks Good but appears to be fragile ? and should be handled gently when operating, since its not bullet proof like Henry's.
If your car is wired properly you don't need any fuses! Maybe your reproduction switch back is the problem. I prefer the pin type switch backs, because you can get them apart easily. Ben Martin does a fine job of rebuilding originals.
Nice, peaceful quiet day up here in New Hampshire.
Just for conversation, I'd add that the good old knob and tube household electrical wiring was just fine - in it's day. Surely modern wiring is not "needed", nor are circuit breakers and well insulated, clad wiring, nor are accessory brakes, but are not modern safety features wonderful to give us folks peace of mind?
Have a great day everyone !
It is a fantastic day in NH.
Bright sun, 65 degrees, low humidity, leaves changing color, and a perfect time for a T ride.
I added a fuse to my T and A.
The the insulation on about afoot of the stop light wire on the A was gone.
They may not be "original" but I sleep better.
My OP others may differ;
I think putting a fuse on the main line is the wrong way to do it. If you are running on magneto and blow the fuse the car will keep going and risk melt down of the generator. I know there is a shunt wire in the stock cutout that should dump the current but I would ratter not risk the voltage spike of fuse blowing and the generator trying to charge a battery that no longer connected because the generator thinks it needs to be charged. I think putting fuses in the light systems etc is better way to go. If you are running a distributor or have non op magneto that would be a different story, the car would shut down.
I think you should repair or replace the switch. A fuse will only disconnect the circuit but it will not fix the problem causing the sparks. And the fuse could cause you to get stranded somewhere while you drive the car.
Protect your generator this way:
and it is from Uncle Ron, so you know it is good.
My 26 touring is a distributor car with no magneto. If it had a generator that would be a problem, My fuses will be installed by the firewall terminal strip, Larry I agree the switch is the problem, but with old cars and old wires stuff happens, Thanks for the info on Ben Martin rebuilding switches, do You have contact information for him, I have a Ford original that needs rebuilding to replace the sparking reproduction switch.
Thank you reposting that information.
Don't fuse the yellow wire from the starter button, if this fuse blows you will have a generator disconnected from the battery and permanent damage can result to the generator. Instal the fuse in the wire from the terminal block to the light and ignition switch. Brad.