Fuse or maybe a circuit breaker?

Tractorcedric · May 24, 2020

Fixing up a TW30 Ford tractor for a friend. The main wire to the harness for the whole tractor was just stripped and twisted together about 6" from the starter. For now I have put a good butt connector there. I like to put a circuit breaker in my Olivers when I redo them. Any of you guys do that? What amperage would I need for a tractor with a cab? Anyone know what was there when a TW30 was new? Thanks!

Billy Shafer · May 24, 2020

I think a fuse would be better. From what I have found over the years. A circuit breaker is not good. On things that move around like a tractor.

Steve@Advance · May 24, 2020

What size wire is it?

The circuit protection needs to be sized to the wire. Usually that will be a 10 gauge, which can only safely handle 30 amps. But chances are the alternator can make more than 30 amps, so putting a fuse in that line will probably nuisance blow at some point. Fuses and breakers don't like being fully loaded for very long. Trying to use a simple inline cartridge or blade fuse is sure to soon fail.

If I were going to put any circuit protection, I would try to get some numbers off the alternator, see what it's output is, then match that number to the next bigger fuse link wire, install it where the wire is spliced.

Even though that will be beyond the useful capacity of the wire, it will protect it from a direct short should that ever happen.

John T · May 25, 2020

If I were doing it I would install a fuse for overcurrent protection which could prevent a fire or other equipment damage. Regarding its rating, its purpose is to protect the WIRE. I (at least how it was done when I practiced power distribution) FIRST size the wire to have an ampacity of 125% greater then the maximum continuous current and then you size the overcurrent protection device to protect the chosen size of wire. Sorry I have no specs or data on that particular tractor and what current you're dealing with so wont hazard a guess as to the size of the wire or fuse, maybe some of the other fine gents here have that info and can help.

Happy Memorial Day

John T

Andy C · May 25, 2020

Perhaps a fusible link. They make them to pretty high amperage.Perhaps the piece of wire that was cut off had been a fusible link that failed at some point and replaced with just a piece of wire.

Janicholson · May 25, 2020

I agree with those educamated guys below. I like a fuse link of the correct rating. A fuse link is more environmentally protected than a replaceable fuse in a holder. Its failure also requires a bit more effort, which might cause more thinking about what caused it to fail before slapping a new one in there. Jim

sotxbill · May 25, 2020

It was.... a fuseable link there that is known to go bad over years of use. Once the connections get a bit corroded, the link start getting warm and then.... the insulation goes, it gets wet and starts corroding more...

WHile I dont know what was there, one size smaller than the main wire going to the tractor,, will create the needed fail point in the system, if there were to be a direct short somewhere. So if there are two wires, use two new "fuseable link" and I would solder them to the existing wire and heat shrink them.

Janicholson · May 25, 2020

Two ideas: The link won't stand soldering, they tend to melt. The shrink tubing should be on both ends! I like to put a dolop of liquid tape on the ends of the shrink tubing. I also like to tie the link to keep it steady, but not confined that could insulate it from normal ambient air. Jim

Fuse or maybe a circuit breaker?

Tractorcedric

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Billy Shafer

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Steve@Advance

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John T

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Andy C

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Janicholson

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sotxbill

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Janicholson

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