Thread: Electrical system improvements and accessories

Hi,

I've got a positive-earth Series II, and it always made me nervous that basically none of the electrical system is fused except for the fuel gauge, windscreen wiper, and brake lights.

Would inline fuses in the wiring harness be a reasonable thing to add? I was thinking of:

• A 30A fuse in the brown wire from the starter switch to the horn
• Another 30A fuse in the other brown wire from the starter switch to the ammeter
• A 5A fuse in the skinny little voltage control box ground wire. Strictly speaking I don't think I need this one, but that wire is so tiny it's going to go up in smoke well before any 30A fuse blows.

My two fuse questions are - is this enough to protect the electrical system? Obviously blowing the 30A fuse to the ammeter means I lose everything, but I'd still rather that than smoke the entire main harness. And secondly - should I add something to the yellow (output) wire from the generator? If that's providing electricity I could still set things on fire when the output is combined with the 30A from the battery.

Finally, is it reasonable to run a negative-earth accessory (air compressor) directly from the battery? I can't imagine the voltage drop while it's running would cause issues, but it doesn't hurt to ask.

Thanks for taking the time to read this!

- Will

Originally Posted by WhatIsClocks

Thanks John. That's a solid idea, I'd planned on eventually doing the tail lights since the wiring is a little more exposed, but I hadn't considered the headlights. I'll add them to the list.

Regarding negative earth accessories, is that also true if I'm running them directly from the battery? i.e. bypassing the ammeter etc.

You can do this, but not in a way that I would consider "safe". The problem is that almost all car accessories assume negative earth, so the case or any metal parts of the accessory are likely to be connected to the negative line. Especially in a Series with lots of metal available to bump into, this is a recipe for an accidental short circuit, no matter how careful you are. You may get away with it, but I would not regard it as "safe".

A number of the Series I have been involved with have had wiring damaged by shorts in the headlight wiring, usually by something rubbing through the harness.