Incorrectly spec'd blade fuses on clone boards

  • I am writing this more as a PSA if anything else since I don't really see any mention of this on the forum. I noticed something very startling regarding the blade fuses that are being used on some clone boards. I am seeing heated bed fuses as high as 30a, fan fuses as high as 10a, and the fuses for the rest of the board as high as 15a. All of these are at least double what they should be, and the fan fuse in particular is 10x more than what it should be. I guess it's one of those things that isn't a problem until it is, but this seems outright dangerous.

    I guess I am curious as to how much of a problem this really is, especially considering that these clone boards are likely less robust than a genuine board. This seems to me like fire hazard territory, and not just ending up with a dead board.

    I know that you really shouldn't exceed 3a on the fan fuse as that has been clearly documented. It kind of seems crazy to have a 30a bed fuse, that's up to 720 watts if you're using a 24v vin, well beyond the point where I feel you should be using an SSR.

  • The fuse's job is primarily to protect the wiring from prolonged faults that arent a dead short circuit which is an infinitely high current on paper.

    Those faults are quite rare, and the 200% fuses will blow almost as fast in response to a dead short, and the mosfets will most likely fail before the fuse blows in such a scenario.

    Still, I'd put in more reasonable fuse if I had them on hand; odds are is unlikely to protect the board any better, but could in theory prevent a fire by overloading the wires if they're not rated for the same as the fuses.

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