What gauge of wire is used from the starter switch to the terminal block?
A #10 AWG. A #12 AWG could be used but if you peak out on amps, well, issues.
Please read Ron Patterson’s post here:
Thanks for the info.
Just to confirm it - ALL 5 wires in the charging path from the starter foot switch to the generator cutout (or voltage regulator is equipped) terminal are supposed to be 12 AWG and that remained from the 1919 year through to the end of production on the starter equipped cars. There are 2 heavy solid yellow wires and 3 heavy yel/black tracer wires and all of them were 12 AWG stranded wire. If you need to change the first wire from the foot switch to barrier strip terminal 3 (third from the left as you face the barrier strip)then you might want to insert an inline 25 amp fuse at or near the foot starter switch end of the Heavy Yellow wire since that is the source of all small wiring in the car and one 25 amp fuse will protect all of the wiring from melting and causing serious problems. Just make sure that fuse is installed in a weather proof case or holder of some type.
You can get the fuse kit here: http://funprojects.com/search?querystr=TFK-1&querytype=all
The link to the description s dead. I would call Birdhaven and be sure the kit is in stock.
Thanks to all. The problem arose on the 26 Coupe that I am working on. Sometime in the past, someone bolted the battery ground to the frame, unaware that the tail light wire was pinched under the ground strap. When I went to test the lights - POOF! The tail light wire went up in smoke, taking out the wire from the started switch to the terminal block in the same run. The customer did not want me to replace the wiring harness, just the burnt wires, hence the wire gauge question. John, I will put in the fuse as you suggest. Thanks again.
Hope the short didn't fry the switch and amp meter ?
if the contact wiper got real hot it could take the tension out of the wiper causing problems and contact pitting. One fuse like John said should be adequate protection in most situations.photo of a after market full fuse block/Terminal strip on a 26 coupe. Which fuses each individual circuit.creating more connections for potential problems. but while providing full protection.
Actually you need to look at the characteristics of any fuse you choose since the idea that a main fuse might need additional fuse has to do with how fast the fuse blows and how heavy or light the lightest wire is that was ever a part of the Ford T wiring. The lightest wire was 16 gauge and can rather easily pop the 25 amp fuse with any sort of short to ground. I think that even if you deliberately tried to over heat the 16 gauge wire you would find it extremely difficult to make your short circuit "just right" so that the fuse would not blow and the wire got damaged. This is because correct type fuses are an avalanche device that once they begin to blow they tend to start to get warm and that effectively reduces the fuse to a lower current carrying device and that is good because if you have an intermittent problem you DO want the fuse to blow. A good electrician in the old days could "read" a fuse and determine by looking at it if he was looking for a low value short and a long delay time blown fuse versus a catastrophic failure. Today you have to know first the exact "TYPE" of fuse you have to then be able to accurately determine what might have happened.
As an aside the original 16 gauge wires as used by Ford had a rather heavy cloth insulation such that if you use a modern 16 gauge cloth covered wire it will look much lighter gauge when compared to original. I recommend that if you compare modern 14 gauge cloth covered with 16 gauge original wire side by side you will see it looks more like original 16 gauge and using heavier wire helps keep things cool even in an overload since the fuse will blow much faster with 14 gauge than with original 16 gauge.