Wiring help

Hi all, I am just about to start wiring in my extras on my project but just want to clarify a few things before I start as I don't want a big fire before I've had chance to drive her so here goes. Everything is run through a auxiliary battery via a fuse board with relays , can the earths for the things connected to the 2nd be connected to the body or do they need to be connected back to the battery?
Secondly I've brought some roof spots and a work light they came with a wiring diagram and wiring kit but I want to use a carling switch instead of the one supplied, but the circuit is earth switched via the relay from what I can make out , how do you wire a carling switch like this ? Or is it best to ditch there wiring diagram and use the positive to work the switch ? New to this wiring thing any help gratefully received.
cheers Ian

Hi,

Always worth a read.
https://www.landyzone.co.uk/land-rover/tutorial-car-electrics.245168/
Cheers

If you are confident that there's a good connection between the neg (earth) side of the batteries and the body it should be fine to use it as the earth point. Now might be a good time to add a new earth strap to the bulkhead. For roof lights I would rather switch the positive power feed than the earth, as you have suggested. This means that if water gets in to the light, it's not going to meet an always live feed somewhere. The new wiring for the roof light power feed will go fuse, relay, light. IIRC, the feed to the switch and relay energisation circuit should really come from your headlight feed, so the roof lights will only come on if your headlamps are on. I think. Plenty of wiring diagrams from google.

Cheers neilly new I had seen that somewhere couldn't remember where been meaning to read it.
Cheers zeaphod yes the diagram for them shows that for the roof lights but me being a dohnut I thought that that meant every time you put high beam on the roof lights came on but it doesn't does it , it makes the circuit work like the rear fog lights no high beam no fog lights . I'm getting there slowly very slowly it must be my age .

Errrrrr ... aren't the rear fogs supposed to come on with the dipped beam?

Yes your right Oldseadog my error got myself so confused know my heads gone.So if I wire it into the main beam and into a on off carling switch will they only come on when main beam is on and the switch is on ? Have I got it fight now ?

Yes.

Cheers zeaphod sorry for being a pain just read your 1st post again.

No worries - keep asking, it's how we all learn!