Togo said:
Evening all,
I'm about to start rewiring and installing new kit in the back of my 110. Once I've done my calculations - the live feeds are simple enough. Can I ask - would you earth the neutral to the car body, close to each light or socket (ie lots of individual earth points), or would you run every neutral wire back to one earth block bolted to a section of steel - so that everything is in one place, accessible and where you know you have a good solid earth connection?
1st time I've had to do car electrics so new to me. How would you do it? Recommendations please.
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It depends on the load you are drawing. I wouldn’t want any earth/return going through my 110 body after my rebuild.

My advice would be to use one of the “standard” earth points, but run a larger diameter wire back to the battery neg. it could connect to the chassis where the battery neg is bolted on for an easier install.

Without knowing the load you intend to draw, giving advice on cable size is useless. My bulkhead earth point, and both earth points next to the rear lights will have 16mm earths on them after my rebuild.
 
Have you thought about a common earth at the rear end of the chassis using an anodised alloy Riv-Nut and a bronze bolt for the connections?
Works well on my galv chassis.
 
Togo said:
Mick '86'.
It sounds like you are doing both. Using existing earth points and taking a lead back to the battery neg. I'd thought of just running everything back to one earth block. I can see the sense in doubling up. If one fails you still have a good earth somewhere else.
You are using earth points at the bulkhead and rear lights. If you use these aren't you still running earth through the body or are these isolated in some way and just going back to the neg?
Excuse my ignorance - is there a downside to earthing to the body - it seems to be what a lot of people do and is mentioned in one of the 'rewiring tutorials' on the site. Just trying to get my head round the best way to do this.
Cheers
Click to expand...

I am “doubling up” so to speak, but the original earths are something like 1.5-2.5mm, and the new ones will be 16mm. Electricity takes the path of least resistance, so the originals will be almost unused.

When you see “electrolytic corrosion” on these vehicles, it’s usually caused because of the presence of road salt and water, and electricity passing through the joint. If you reduce the electricity passing through the joint, it has to reduce the corrosion. How much it will reduce it is up for debate though.

All of my current earths will be wired direct to the new 16mm earths, and not through the body. Yes the body will be earthed by virtue of the 16mm connections, but the body shouldn’t ever have power passing through it.
 
mick 1986 said:
I am “doubling up” so to speak, but the original earths are something like 1.5-2.5mm, and the new ones will be 16mm. Electricity takes the path of least resistance, so the originals will be almost unused.

When you see “electrolytic corrosion” on these vehicles, it’s usually caused because of the presence of road salt and water, and electricity passing through the joint. If you reduce the electricity passing through the joint, it has to reduce the corrosion. How much it will reduce it is up for debate though.

All of my current earths will be wired direct to the new 16mm earths, and not through the body. Yes the body will be earthed by virtue of the 16mm connections, but the body shouldn’t ever have power passing through it.
Click to expand...

Excuse my ignorance on all things leccy, but is that not just the same?
 
Well, if all your earth's go to one point how do you join them all up and where do you attach it? I know the battery but are you leading straight into battery? What if you get multiple earth issues at once? (can that even happen? )
Not criticising, just interested.
 
Lionhound said:
Well, if all your earth's go to one point how do you join them all up and where do you attach it? I know the battery but are you leading straight into battery? What if you get multiple earth issues at once? (can that even happen? )
Not criticising, just interested.
Click to expand...

I will have a “standard” earth setup from the battery, so that’s neg terminal, to chassis (gearbox mount bolt I think), then onto gearbox/transfer box. That is pretty much as a standard 200tdi is. I will then have two 16mm cables, with ring connectors on, joined to the chassis bolt that has the main neg cable (gearbox mount bolt). These two 16mm cables will go to the bulkhead earth point and the rear light cluster (drivers side). The rear light cluster will join across to the passenger side. All of my loom earths will then connect to these 3 points. The chassis will still be earthed via the standard bolts and earth wire. The body will be earthed at the bulkhead, and rear light clusters, and all body mounts. The body mounts cause a problem on mine here, as my body mounts and all metal to metal joins have some form of gasket.

It will be far easier for me to trace an earth fault with the new setup. It will simply be a case of resistance testing the connection points back to the battery negative terminal. If that is a SC, less than 1 ohm, then the connection is good. If it’s higher than 1 ohm, then it will need investigating. Once I get to that stage, I will take photos and log what I have done.
 
IMHO, do not rely on the body to earth anything. As others have suggested, I'd run a heavy earth from the battery or chassis earth point to the rear - to where the rear loom is joined to the individual lighting circuits. - inside the cover in the rear drivers side on most UK vehicles.
 
Togo said:
I quite like Oldseadogs idea of a chassis earth at the rear. How about this plus running an earth to the original front chassis bolt on point for the negative cable from the battery? This way there are strong earth points at each end of the chassis. The circuit is made through the chassis earthing and there is no current passing through the body to stimulate electrolytic corrosion. Is there any need for earthing the body at all given this set up?
Just trying to find my way here (a little knowledge is dodgy & I don't want to get this wrong).
Click to expand...

This is what I explained in my previous posts....I think. Connect 2 off 16mm2, welding extension, cables from the battery negative cable to chassis earth bolt. These will go forward and rearwards. The forward one connects to the bulkhead earth point. This will be for lighting earths instead of the inner wing earths, heated screen earth, and a separate earth for the dash binnacle.
The rear one will go to the drivers side lighting cluster, then branch over to the passenger side (not sure if 6mm2 will be enough for this one yet). This rear earth will be for things like rear lights, roof lights, reverse camera, possibly rear heated screen, tow bar socket.

Using this setup should eliminate the need for a body earth.

Edit: I personally would not trust the chassis for a reliable earth. The cost of 16mm2 and 25mm2 copper welding extension cable make reliable earths far more cost efficient than in previous years.


zeaphod said:
IMHO, do not rely on the body to earth anything. As others have suggested, I'd run a heavy earth from the battery or chassis earth point to the rear - to where the rear loom is joined to the individual lighting circuits. - inside the cover in the rear drivers side on most UK vehicles.
Click to expand...

I agree about not trusting the body for earthing. Unless a full rebuild is done, body condition is speculative. Dedicated earths are the way I will be going.
 
Togo said:
Gotcha. Thanks for all the advice guys. Think I'm up to speed on the earthing side of things. No doubt I'll be scratching my head on other stuff but one thing at a time.
Click to expand...

It’s better to ask a question on here and get someone take the ****, than assume and potentially set something on fire.
 
When you do a wiring job make sure its easy to diagnose if something goes wrong, Its easy to run wires all over the place , red and black wiring for everything for instance isnt a good idea, dont over complicate things for the sake of reliability..
 
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