Spitfir Mk2 Fuse Ratings

[Peter Truman]

My daughter's moving house so her 66 Mk2 Spit has come home for a holiday whilst they get it sorted,

I'm going to check the engine out & fit the J Type OD whilst it's here, but when I removed the dash scuttle H frame I noticed some wiring needed sorting out, extra things added over the years!

So in an attempt to determine what was connected to which source I noticed the car as assembled by Triumph had two in line battery source fuses, one for the horn relay, and the other for the headlight flasher, in addition there was the usual fuse box with two fuses one Ignition supplying all the heater, gauges, brake lights, turn lights, & wiper motor, all logical and fuse rated at 35Amp seemed appropriate for the load, the other fuse was Battery but only supplies the 4 parking lights and number plate light all 6watt bulbs (manual states) so less than 3Amps, so why does the manual advise a 35Amp fuse, standardization so you can't confuse the fuses? Really I thought fuses were supposed to protect the wiring so why overrate them, I've replaced it with a 10amp fuse, where 5 would have done, as I use LED's I might go down to 5?

Triumph's thought process's confuse me sometimes? 

One of the fix's I've done was to refix the Cigar Lighter supply by piggy backing off the original in line 15 Amp fused Battery supply to the Horn Relay C2 terminal & then in line fusing close to the C2 terminal source (double spade) for the Cigar Lighter with a 10Amp in line fuse yes it's fuse in line with fuse? but hey it'll tell me the cause of the fault Horn or Lighter. Why 10 Amp for the Cigar Lighter when the daughter only uses it as a phone/USB supply, you just never know what the Son in law might hook up, small beer fridge, I hope SMALL, a big one wouldn't fit in the car anyway??, I did use heavy gauge 15Amp wire (purple) for the Lighter just in case?