Wiring Loom Wire Ratings

Discussion in 'Vintage Classics' started by chiari1, Apr 17, 2020.

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  1. chiari1

    chiari1 Elite Member

    Mar 19, 2016
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    #1 chiari1, Apr 17, 2020
    Last edited: Apr 30, 2021
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  2. Wire-Wheels

    Wire-Wheels Elite Member

    Apr 26, 2019
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    California - USA
    #2 Wire-Wheels, Apr 17, 2020
    Last edited: Apr 25, 2020
    This is all calcultated using ohms law. It states that "Voltage times amperage equals wattage". That can be reversed as well, by dividing. So if you have a tail light curcuit with 2, 15watt bulbs running on the same fuse, it would total 30 watts for that curcuit. 30watts divided by 6 volts equals 5 amps.

    Next the wire size. It is determined by the amperege, not the voltage. The chart for that reads something like this:

    30 amps.= 10 gauge wire.
    20 amps = 12 gauge wire.
    15 amps = 14 gauge wire.
    10 amps = 16 gauge wire.
    5 amps = 18 gauge wire. I hope this helps. ...J.D.
     
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  3. Triumphal385

    Triumphal385 Active Member

    Mar 23, 2020
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  4. Wire-Wheels

    Wire-Wheels Elite Member

    Apr 26, 2019
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    #4 Wire-Wheels, Apr 17, 2020
    Last edited: Apr 17, 2020
    The only thing I would add is that I usually do those calculations with a 10-20% safety factor. The wattage remains constant, so add 10-20% to the wattage before you do those calcs. That is because if your system voltage is low, the amperage goes up. Keep that in mind when calculating. Enjoy ! ...J.D.
     
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  5. Wire-Wheels

    Wire-Wheels Elite Member

    Apr 26, 2019
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    Just old dusty files back in a mental file folder. Don't use that brain cell much anymore. I have been retired a long time :) ...J.D.
     
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  6. Old dumb arse

    Old dumb arse Noble Member

    Mar 28, 2020
    909
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    KS
    Wire amps need to be equal to or greater than fuse size would be the only thing might add.
     
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  7. Wire-Wheels

    Wire-Wheels Elite Member

    Apr 26, 2019
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    #7 Wire-Wheels, Apr 18, 2020
    Last edited: Apr 25, 2020
    Agree. The fuse is really there to protect the wire. For.example, you might have several devices on one curcuit. In such case the fuse size would be determined by the wire gauge feeding it. The wire gauge is determined by the total amperage of all the devices on that curcuit. Wire and fuses often have to be used in the next larger available size. ...J.D.
     
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  8. Wire-Wheels

    Wire-Wheels Elite Member

    Apr 26, 2019
    2,165
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    #8 Wire-Wheels, Apr 19, 2020
    Last edited: Apr 19, 2020
    Really sounds like some upgrades would be helpful. I am not the guy to advise you in that regard. You need to get with some of the guys that work with the older stuff. They could advise you on the best upgrades available. I play with the Hinckley era stuff myself. ...J.D.
     
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  9. Oldfart

    Oldfart Senior Member

    Oct 25, 2019
    502
    243
    Staffs Moorlands
    Hi chiari1
    I've got a solid state rectifier for my '65 BSA A50, which I've yet to fit. Perhaps the wiring diagram that came with the device will help you, I'm not sure it has a diode built in, I know that my bike hasn't a Zenner, (neither has it any fuses!). I believe they were only fitted to 12v bikes.
    Please bear in mind my bike is 6v and is Positive earth.

    Oldfart

    IMG_0801.jpeg
     
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