To fuse or not to fuse - that is the question

George. hope this can help in some way to calculate fuses ect. i would put a fuse in. as close to the battery terminal as poss.

http://www.rapidtables.com/calc/electric/watt-volt-amp-calculator.htm

Slight confusion here George. A 15A fuse is safe to a 15 amp current. Wattage is a unit of power. Most fuses have a continuous rating (say 15 amps) and anrating at which they blow (say 25 amps). Fuses in a bike circuit are there to protect the battery in case of a short circuit. I would definitely have a fuse in the circuit. Having a battery short to earth is not a good thing... Have you ever seen what happens if you drop a spanner across two battery terminals? Don't try it at home.

Just remember watts = amps X volts Or amps = watts/volts!

Norton probably didn't fit a fuse as the average ride to work rider would have blown it every time that he changed a bulb and been too hard up to buy a new one.

I cant think of any good reason not to fit a fuse and if you have an electronic regulator then it's pretty much essential. Even without, it could save you from a fire.

If the reg is electronic then the manufacturer may well have a recommendation. I have a 16a in-line.