Thread: Should I run an earth cable?

If it was me I would be running a cable all the way to the battery, as compressors do draw a fair amount of juice, as the wiring in the rear power outlet would not be thick enough.

An earth to the chassis would probably be ok, but an earth wire back to the battery would be better and if you are running one wire(positive), two is just as easy.

I would recommend as the bare minimum 6mm, but I would probably go the next size bigger, being 8 B&S

Tim from Drivesafe would be the best to recommend cable size. If he does not see this thread and respond, send him a PM. He would only be too happy to help.

yep, Id be expecitn it to be around 35mm2

the smartest thing to do would be to put a primary fuse in up the front, hook up to your battery then put a dist fuse block in down the back and QD connectors for the compressor (because then you can hot swap in inverters, chargers, whatever else is in the 60A draw range.

Running both cables to the back seems to be "future-proofing" idea in the event I end up running other appliances in the back. Glad I asked!

Cheers

What I would do is run a dirty great earth cable from the back of the transfer case to your power outlet area, and earth it to the body there too. The trans is sufficiently conductive to act as an earth path from the battery. Having a large capacity Anderson plug at the rear of the vehicle lets you jump start from the back of your vehicle, either your own or another vehicle. Big inverters can just be plugged in. Jumper leads made with an Anderson plug joiner are easy to get. Example:

Battery Pack Jumper Leads 2M With 175 AMP Anderson Plug 4x4 | eBay

Me, I'd do what Mr. bee utey said. Maybe even earth to the nearest bit of the chassis.
But, consider this, that method relies on a number of connections to the battery that may develop some resistance/voltage drop with time.
You get around that by running another earth cable to the battery which is more expensive and adds weight. Also circuit isolation becomes more complex.
Both of these methods are neither right or wrong. It's just what best suits.

Hi Jason, as a number above have posted, and why not future proof your setup.

Depending on the current draw of the compressor, as d2dave posted, in my case I would go for 8B&S minimum.

If it was my vehicle, having to run a cable all the way to the rear, I would aim at setting up to be able to charge batteries in a caravan or camper trailer, even if you don't have one at present.

The optimum setup would be 6B&S as this would not only keep voltage drop to a minimum level while using your compressor, but would allow for decent house battery charging capabilities when towing.

BTW, you can easily jump-start through a 50 amp Anderson plug and 6B&S cable.

Word of caution, a 60 amp fuse is the largest current rating you can use will 6B&S but I usually fit a 50 amp auto resetting circuit breaker, for added protection, and you can still carry out a jump-start with this setup.

Also as a number above have suggested, run an earth all the way the the front. This removes any potential problems that chassis earthing can cause, but there is also nothing stopping you fitting earth straps ( cables ) front and rear as well.

NOTE, the earth return cable must be equal to or larger than the positive cable.

Beware - the D2 chassis is not earthed unless an earth strap has been fitted or indirectly earthed via a chassis-mounted winch that is also earthed to either the body or battery negative post. It is only earthed via the uni joints and steering joints so significant current draw will damage the bearings. LR uses only the body for earth.

Originally Posted by jasonharrison

I have an ARB compressor that I'd like to hard-install in the back of my D2, instead of having to repeatedly open the bonnet make the connections etc etc.

Should I run an earth cable to the compressor or would earthing to the frame be okay?

Where would be the best route to run the power cable?

I ran twin 50mm2 (0B&S) to the rear of my D2, fitted with 150A CBs at both ends. This would be the largest size that realistically you could feed into the back without major headaches.

The run was from the battery, along the drivers side wing top, across the top of the firewall tucked in behind the main engine bay wiring loom (V8) and down to the top of the passengers side chassis rail.

Then to the rear along the top of the chassis rail, weaving in and around various obstacles like the air compressor box etc. At the rear, I feed the cable up from behind the rear bumper to where the rear tail assembly is on the pillar. When you remove the lamp assembly you can see a covered over hole that a smaller size cable can be run through with an appropriate grommet. However, the larger sized cable takes up too much room and will not clear the lamp assembly. In my case I drilled a 35mm hole above where the tail assembly goes and ran the cable the left hand side.

Once the cable is inside it can then be routed back down and is accessible via the left hand vent (plastic grill cover). I installed a 12v outlet on the side plastic near the door strike and a 150A Anderson plug hanging on a length of cable tucked up in the recess. Mine was a 7 seater and this kept the install tidy when not in touring mode.

Cheers
Ron