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power wattage question

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  • power wattage question

    most of the application guides for running amp wires etc refer to how many wats RMS a amp will draw for example
    also they state that it is based on the Power of the amplifier with a 50% efficiency rating.

    most psu's like the opus 250 are very high efficient (99-100%?) 95?
    so given that situation do these sizes still run true

    id like to run 10 ft of 10ga to power the opus but i think that might not be enough but im confused on whther the efficiency matters
    -thx lost
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  • #2
    Efficiency always matters. I have my doubts that it is anywhere near 99%, but that's just me. I would estimate 80%. So, if the max output is 250 watts with 80% efficiency, it will need 312.5 watts on the input side. That translates (roughly) into 26 Amps. Get a wire size using the calculator here

    Remember, fuse to the size of the wire, don't let your car burn down if the wiring shorts.


    • #3
      I'd say worst case, your pushing the 250W power suplly at 10 Volts. but check out the input limiting fuse on the power supply. That's the ampacity you need to cover with the wire you choose. So if the fuse is 25Amps, then you can trust the engineering of the supply and say you need a wire that will handle 25 amps minimum. Then use an ampacity table to determine the sixe of the wire... like the kayjayco one I linked to in this thread. 12AWG cuts it close, but 10AWG covers it nicely. I'd say you can implement your plan with no worries. And if the wire goes in the engine compartment, go XLP (CROSS LINKED POLY).
      It's been a while...