circuit breaker

My PUP has a 30 A fuse coming directly off the battery..

Hi,

How many amps is the converter?

Probably has a part number with the rating. I would go 40a max unless you find it is more.

Probably 40 or 50 amps. Should be marked. :)

2002 keystone hornet

30 amps at 12VDC is 360 watts. I'm thinking the fuse/breaker would be a LOT larger. Some info on your RV make/model would be extremely helpful.

It should be labeled with the capacity, which should be based on the wire size primarily.

I would guess it's quite a bit larger than 20 or 30A—somewhere around 50A to 100A or so, perhaps. But please don't go by my guesses alone for a safety item such as this.

It should be marked.
If not, what you are protecting with the breaker is the wire and circuit that goes to the battery. You can choose a breaker size that is at or smaller than the amperage rating of that wire. The wire should be marked as "AWG 10" or SAE 12" or such.

Here is a wire---amperage chart.

I believe a common size for these breakers is 40 amps. That is usually the largest amount of current the converter makes when charging the battery. The converter/charger usually is the largest amperage on the wire. If you have large cables from the battery to the converter and distribution panel, you may have a large converter. It would take a bigger circuit breaker.