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Thread: How to select correct fuse amperages and types

  1. #1
    Maximum Bitrate
    Join Date
    Jul 2006

    How to select correct fuse amperages and types

    Here are my components and the wires I was thinking of running to them:

    AMP 300W/12V = 25A 4AWG

    CNX-P1290 90W/12V = 7.5A 12AWG

    Monitor 8W/12V = .66A 12AWG

    Laptop 60W/12V = 5A 12AWG

    Hub 15W/5V = 3A 12AWG
    TOTAL 390W/12V = 32.5A, 4AWG

    My questions are:

    1) How do I select the fuses for these components? Is there a formula such as adding 10% of max amps?

    2) I wanted to use a distribution block to split the power wire from my battery between the amp and power supply. However, both the main power wire and the wire to the amp need to be 4awg (Anything bigger would be overkill, and 8awg is too small for for the amp because max amps for 8awg is 24A). How can I get a distro block that would take a 4awg-->4awg+12awg.

    3) Do I need fuses after my power supply and before my components such as the PC, LCD, or Hub?

    4) Are these types of inline fuses and fuse holders ok? They say they are rated for 32V and not 12V, but they are car fuses?

    I think that's it. Thanks all

  2. #2
    Maximum Bitrate v8 scimitar's Avatar
    Join Date
    Jan 2005
    In short fuses aren't there to protect the equipment they are there to protect the cable. Say you use a cable that takes 10A you use a 10A fuse, you can make them smaller if you want but it wont serve any purpose. The fuse goes at the power supply end so say main cable to distro the fuse is at the battery, other fuses are at the distro. The equipment will have its own built in fuse or should have anyway.
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  3. #3
    Maximum Bitrate
    Join Date
    Jul 2006
    so there's no risk of frying my xenarc if i use a 10amp fuse on its line? i thought i need to protect it from surges even if they are smaller, like 5A?


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