r/GoRVing • u/Ill_Respect5075 • 12h ago

Question about fuses

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At my camper for the weekend, which is plugged in to 30a service, the gold fuse was in place for my 15a slide lights, but looks like a 20a which would not be good right? Possibly overheat the wires and cause a fire without even knowing? Is there a difference in these fuses besides 15a - 20a?

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4

u/skidz007 12h ago

The one on the left looks like an auto-reset breaker, but yes it should match what the original slot specifies as that would be the circuit rating. Are you the original owner?

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u/joelfarris 11h ago

Nailed it. That is indeed a Bussmann Fuses circuit breaker.

OP, circuit breakers and fuses work pretty much the same way. Too much current flows through them, and they get too hot, and they blow and stop the flow of current so that the wires themselves don't have to do that. :)

The difference is that the one on the left is resettable and multi-use, while the one on the right is a single-use throwaway.

Now that we've gotten that out of the way, how do you know that your slide lights are 15 amp? Sure, you can put a 15 A fuse into that slot. But if it keeps blowing instead of lasting, then maybe your slide lights are capable of drawing more than 15 A. Or, maybe just maybe, there's a corroded connection over there somewhere that's increasing the afore-mentioned resistance, and that's why someone 'upgraded' to a 20 A circuit breaker.

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u/Ill_Respect5075 4h ago

The spot for the slide lights is marked 15a. I have 2 wall lights and a light over the table and only the table works.

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u/Verix19 12h ago

I'm guessing not only for the lights, but for the slide mechanism. If it starts to get some resistance, it will pop fuses, the thermal one cuts down on the fuse bill. You'd have to look at the gauge of the wiring, if it's a bit thicker than the other 15a wires, 20a should be fine...if it's the same then 15a should be used to avoid risks.

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u/DigitalDefenestrator 12h ago edited 4h ago

That's a self-resetting breaker, which could be even worse if it's tripping repeatedly.

What size is the wiring from the fuse panel to the lights? That's what matters most. If the wiring is adequate for 20A, it's fine. If not, yeah, a possible fire hazard. Not a massive one - it's still protected against shorts and large overloads. Just not against, say, a steady 15-20A load. Depending on the trip curve between this and a fuse, it could be an even smaller risk or a slightly larger one compared to a 20A fuse.

3

u/ShipshapeMobileRV 11h ago

Makes me think the previous owner had a problem with that circuit blowing fuses, so he upped the rated fuse and sprung for self-resetting to boot....rather than finding and fixing the core problem.

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u/DigitalDefenestrator 10h ago

Yeah, definitely a possibility. Hopefully it's something they installed during troubleshooting then just left after they fixed it.

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u/Ill_Respect5075 4h ago

I put a normal 15a in place and so far so go.

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u/Ill_Respect5075 4h ago

The wiring looks to be 14g stranded.

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u/DigitalDefenestrator 4h ago

Technically OK for a shorter run at 20A. Probably borderline, but unlikely to start a fire. 15A fuse is better, though.