For homeACcircuits, the arcing-on-tripproblem is very small, because the voltage drops to zero every 100Hz/120Hz, at which point the arcing naturally dies off.
Polarity doesn't matter toDC Fuses - both ends are generally the same design. But beware that fuses also havemaximum voltage ratings, above which arcing can become an issue.
Here is a DC breaker from a very respected manufacturer. "DANGER: Correct voltage polarity required"!
It's got theclearest diagram and markings I could find. Most polarized DC breakers have similar, but far less clear markings.
My poor attempt at trying to illustrate the problem when connecting a battery with such a breaker. The solar panel was perhaps a poor choice... imagine a charger or a hybrid inverter instead.
Normal operation:
When there is a short circuit on the battery side, the breaker trips successfully, as it was designed to do. So far so good.
But when there is a short circuit on the PV(/charger/hybrid inverter) side, things can get ugly. The power is now at the bottom, andcurrent
through the breakeris now flowing in the wrong direction. It's not designed to trip safely in this configuration, and could start to burning like in the YouTubevideo I posted earlier.
Here's another video showing the dangers of wiring a polarized DC breaker thewrong way.
Now,personally, I assume that a polarized DC breaker rated for 600V will work correctly bi-directionally when running at less than 60V. But nobody will guarantee that.