How large fuses compared to DC load?

[qwerty11]

So I am wondering how much larger the fuse should be at the fuse panel compared to the load on the line. For example, size of fuse for radio pulling 5 amps, size of fuse for outside light pulling .833 amps, size of fuse for interior lights pulling .5 amps.

[Dale M.]

I usually run a fuse 25%-50% larger than actual load.... For you small loads actually a 1.5 amp fuse is plenty and your 5 amp radio maybe 7.5 amp...

Dale

[working on it]

Are you running the items straight off the battery, or switched, or further protected by a circuit breaker? If you have high dollar items, I'd run an inline 40-50 amp circuit breaker (to protect circuits when charging) prior to a master cut-off to the fusebox. Then use the smallest rated fuse (nearest to the mfg.'s product rating). I once piggybacked on a 20(?)amp circuit (wipers) to power an auto stereo (rated for 10 amps); the radio fried when the wipers overloaded with ice. I've also had machinery drive motors fry when too high an amperage fuse was used. Granted, those are just marginally related to your planned usage, but since then I'd rather replace an easy to reach/buy fuse, than an expensive item. On my trailer, I have three lighting circuits that are unfused, but still switched, inexpensive, easy to replace. But the Pioneer Stereo has a built-in 10 amp fuse, is fed from another 10 amp fused line, from a master switch, from the circuit breaker. My wife may be in the wild with this trailer, and I would rather have a fuse to replace later, than a fried stereo/burnt trailer. Worst-case scenario? The ac system is GFCI based; items there have their own circuit breakers.

[qwerty11]

Are you running the items straight off the battery, or switched, or further protected by a circuit breaker? If you have high dollar items, I'd run an inline 40-50 amp circuit breaker (to protect circuits when charging) prior to a master cut-off to the fusebox. Then use the smallest rated fuse (nearest to the mfg.'s product rating). I once piggybacked on a 20(?)amp circuit (wipers) to power an auto stereo (rated for 10 amps); the radio fried when the wipers overloaded with ice. I've also had machinery drive motors fry when too high an amperage fuse was used. Granted, those are just marginally related to your planned usage, but since then I'd rather replace an easy to reach/buy fuse, than an expensive item. On my trailer, I have three lighting circuits that are unfused, but still switched, inexpensive, easy to replace. But the Pioneer Stereo has a built-in 10 amp fuse, is fed from another 10 amp fused line, from a master switch, from the circuit breaker. My wife may be in the wild with this trailer, and I would rather have a fuse to replace later, than a fried stereo/burnt trailer. Worst-case scenario? The ac system is GFCI based; items there have their own circuit breakers.

I'm going to have an in-line fuse right off the battery. Lights and what-not will be on a switch. The radio will be wired directly from the fuse block.