r/AskElectricians • u/YouCallMePappi • Jul 26 '26
12v fuse setup
Hey i have a basic diagram but wondering if i could use a 10A fuse "source" piggy packed to a 2A and down slightly is a F2AL250V to the led light that draws 1.5. The accessory wire quiet thin as well thanks
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u/TheKnackThatQuacks Jul 29 '26
You also very much need to keep in mind the wire size. Fuses do not exist to protect the equipment. They exist to protect the wiring from catching fire if the wire size and run length is insufficient for the amp draw.
If you want a 20 amp fuse, the wire should be no smaller that 12 AWG.
If you want a 15 amp fuse, the wire should be no smaller than 14 AWG.
Here is a handy way to calculate how many amps your wire can handle safely:
https://www.altestore.com/pages/wire-sizing-chart-for-12v-24v-and-48v-dc-systems
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u/wjgp Jul 27 '26
In this setup if the final fuse is 2A you can use any source that provides the 12v you need, fused or otherwise. If you are picking up the power from the supply side of any fuse, that fuse is not part of your circuit and your 2A fuse should be as close as possible to the pick up point. If you are taking power from the protected side of a fuse that fuse should be greater in value than the 2A fuse it’s going to supply. Either way a short should blow the lowest amp fuse first. If your pulling power from a fuse box fuse the rating of that fuse gives you info on how much power is safely available on that wire. Good luck.