Fuse size?

[working]

What amp fuse on the tow vehicle would be correct for the black 12v hot on my connector? I have an original uni-volt in my 67 Safari.

[thenewkid64]

The typical size used in newer models is a 50 amp fuse. I would place it as close to the start of the feed to the trailer as possible. At you local autoparts store you can get a blade style in line connector with pigtails that can hold the fuse and has a weatherproof cover to keep it clean and dry.

My $.02 worth....................

[FrankR]

Since all things are relative....
Fuse size is very relative to ..power needs, length of circuit run, wire size and intended load. This dedicated circuit should be used for keeping the trailer batteries fully charged while in transit. Using a 30 amp fuse would be more than adequate. A fuse of 30 amps will power many electrical devices. Some RV tow vehicles are wired to operate the power tongue jack with this circuit. The jack is always operated with a full and ready battery of the tow vehicle.

[jim8860]

With out a question wire size an the load amount is important. If you are charging a "house" battery while driving I would use a 4 guage wire with a 50 amp fuse. That should do the job.You can get the fancy fuse holder and stuff from any stereo store. They use it when an extra battery when they have a buch of amps..An other way is to install a battey isolater .That allows your truck to charge 2 batterys correct.

[RONALD DODA]

I recently changed my inside fuse in my 1975 32' to a 40 amp. I could not find a 50 amp fuse for the main pannel. Should I keep searching for a 50 amp fuse or just run it on a 40 amp. its a big ugly fuse thanks Ron

[FrankR]

Fuses are a safety electrical connection. The size, shape and beauty are of no importance. The rated ampacity is the critical requirement. I often use ac fuses for dc. My electrical engineer friend advises that there is as little as 10% rating difference in comparison. With a 40amp fuse the difference is just 4 amps. Most fuses will fail suddenly, but some fuses will fail after an overload condition has been met. Fuses are great circuit protection, but my preference is to manual reset type circuit breakers. The cheap circuit breakers have less accurate amp fairure. Ac breakers can be loaded higher than the nameplate rating. The aircraft circuit breakers are the best. These breakers are some times rated at a wide variety of amps and open right on the rating.