Got a bit technical, this "thread!" I was told a hundred years or so ago that most old Brit. bikes have only 5 wires! Having a sidecar and indicators etc. I have a few more! I also run a Lucas 12 volt car dynamo. I have one main fuse .On my Morini the wiring looks like spaghetti junction [english joke to do with Birmingham motorway] and innumerable fuses! My original headlamp master switch never gives me any trouble [pattern parts, just don't mention them], but on the handlebars I have fitted a black Modern switch from some Japanese make that has everything you could want instead of old type separate Brit switches. Nothing complicated, no relays or "black boxes" to go wrong! I'm lucky, because if I have an electrical problem I can't solve, I pop round to J. Bickerstaff for friendly advice!!