Wiring Loom Wire Ratings

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.

 

You might find the following web page to be some use.

https://www.12voltplanet.co.uk/cable-sizing-selection.html

 

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.

 

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.

 

Wire amps need to be equal to or greater than fuse size would be the only thing might add.

 

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.

 

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.

 

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