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I am working on a project with some 12V LED strips and am planning on powering them with a Mean Well LRS-150-12 power supply (12.5A @ 12V).

My total LED strip load is about 10A.

I was planning on wiring a fuse holder to the output of this power supply with a 10A fuse for protection, but I was just thinking, is a fuse actually necessary in this case?

The power supply can output 12.5A which is just slightly more than the LED strips can draw. The wiring can handle 12.5A just fine.

Is there a failure mode of a power supply that could cause more than 12.5A to be outputted, which would necessitate a fuse, or can I rely on the power supply limiting the current to 12.5A @ 12V which everything can handle so no fuse is necessary?

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A power supply doesn't exactly "output" more current. It's voltage could perhaps rise, resulting in more current (if the load draws it). As they age, they become less stable, but this is not as likely on modern supplies as it would be on ones made before the 90's.

Fuses are also commonly used to protect the supply. If there is a short on the load side, either due to some sort of component failure or human error, a supply may over-stress and either burn-out (stop producing power) or burn-up (fire).

That being said, that datasheet you linked to states "short circuit / overload / over voltage/ over temperature" protection, so the device should limit its output to protect itself.

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I have that same exact power supply, and it has built in overcurrent protect - it crowbars hard and shuts off the output when overloaded. It also has a built-in internal fuse on the AC input side. No additional fusing should be needed.

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According to the datasheet, your supply is short protected, so it doesn't need an extra fuse to protect it.

You'd want fuses in the case of, say, 10 LED strips drawing 1A each, and each wired with wires rated for 1A (but not 10A). In this case the supply is powerful enough to melt the wires if a short occurs, and per-circuit fuses are needed to protect the wires. Since your wires are rated for the full supply current, this doesn't apply, so no need for a fuse.

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I think Meanwell take care about protection into their power supply, Still If something wrong happen at your circuit side which short the loop and cause to flow high current. To take precaution in this situation Its better to use Fuse after output power which also make sure about protection for your power supply.

So Choose fuse as per your required rating which will make life easy.

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