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Every dog has his day
nissan
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Discussion Starter #1 (Edited)
Ok not wanting to pollute another bloke's thread, but I did promise to do a more detailed how-to of wiring electrical boards etc for the aftermarket electrical stuff in your patrols or camper trailers. It is much easier than you think. Ok I choose to use sheets of ally, whether flat sheet (bolt to a flat surface with spacers to allow for nuts and wiring underneath), or bent into a top hat to achieve same purpose, or sometimes in a box with a perspex lid if I want it really pretty :)

But you can use whatever is available, the idea is to have as much of the wiring as possible in one place, making it far easier to diagnose faults from relays, blown fuses etc.

Ok I'll start with fuse blocks. These are the commonly available type from any auto parts store, Narva brand, available in 4, 6, or 8 fuse blocks. They have individual inputs, which makes a mess. Easier to have one input, I usually use 8B&S (about 7.5mm2) but may go to 6B&S, depending on what current is to be drawn from it.

Take into account, things like spotties and an air compressor are not likely to be used at the same time, if you're pumping tyres on the side of the track at night, you don't need spotties on, so they can be on same fuse block but don't necessarily have a cumulative current draw.

Ok the way I do it; a vice is handy, just to hold it in place, bend all but one of the terminals toward terminating end. Strip the insulation from the wire to the appropriate length and twist it. Hold it up the last tab (the one not bent) and solder the wire to each tab.


Then, with a small hammer, gently tap the last tab in the opposite direction over the soldered wire, and solder that one to the same wire.


Ok the protect it, I use 7mm split tube. Feed it along the cable from the other end, and pull up enough to cover the tabs on the fuse block like this.


Then run a bead of silicon along the soldered wire. Black is best but I could only find clear, as I'm only doing this whole thing for demo purposes I'm sure you'll forgive me.


Push the split tube on the the soldered tabs and wire, and lick your little finger so silicon doesn't stick to it, and run it along both edges to get a smooth finish. Put some more silicon into the hole in the end.
It should look like this.


If it tries to pop off, put a cable tie or two around it just tight enough to hold the split tube in place until the silicon sets, then cut the cable ties off later before you mount the fuse block.

Ok the other end of the wire... Cut to appropriate length and strip the insulation. For 6mm or 8B&S, yellow ring terminals will be fine. It is well worth investing in a quality pair of ratchet crimpers. At home mine are Kingcrome ones, cost about $50 a few years ago, and are just as good as my $120 set I have in my work toolbox. Ok with ALL ring terminals, after crimping, I solder the tip where a little bit of wire pokes through. It just makes it an even better connection, both mechanically and electrically.


Then cut the split tube to length, and fit a small length of the appropriate diametre heat shrink over the end, and shrink it with a small blow torch or a heat gun.


Ok that's your fuse block.

Next post I'll start a distribution board.
 

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Every dog has his day
nissan
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18,104 Posts
Discussion Starter #2
Ok the distribution board...

For relays I use relay blocks. They are about $6 or so from parts stores. Much better than using just relays, if you suspect a faulty relay, just pull it out and plug in another.
To use these effectively, you need some NON-insulated terminal crimpers. They crimp two different sizes at once; the wire and the insulation part. You can fit 6mm into these, or one 4mm wire, or up to TWO 3mm wires twisted together. This is important when running the earth (85 pin) from one block to the next, or same trigger for multiple relays.



Now it is REALLY important to solder these wires in as well as crimping, otherwise they can pull out a bit too easy for my liking, especially single 3mm wires.


When you hold it down with the soldering iron, it is easy to accidentally flatten the little tang on the back that stops it popping out of the relay block. If needed, poke a small flat head screwdriver under it and bend it back out a little.


Ok we've got a few wires in, and we bend them at right angles at the same length to keep them all neat.


We can start mounting things to the board. We'll use two relay blocks, a fuse block, and two circuit breakers. The circuit breakers, in our example, are a 20 amp for electric brake controller on our camper, and a 40 amp,for the anderson plug that charges the battery in the camper. You see I've bolted a thin strip of ally between the two, this can be as long as needed as a bus bar to power all the circuit breakers. The power goes in on the right, to both breakers, then from the last one goes on to the fuse block. To get wires through the ally if needed, there a a couple of methods I'll show here. Ok a 12mm hole and wiring grommet is the perfect size for 7mm split tube, but you will need inox or similar to get it through, like so;


Ok we're taking a bit more shape. We have screwed on the circuit breakers, the fuse block, and the relay blocks. They are for an air compressor and a pair of spotties on the bullbar.
We have run a 6mm power supply for each of the relays from the fuse block.


As well as the outputs for these, we need to use as many different wire colours as possible. Now to make this close to real world, we'll also have fuses for a UHF, a fridge, a pair of LED rock lights, and a rear LED camp/worklight.
Now 6mm is hard to get in colours other than red or black, so to differentiate, I do silly things like cut the other end at a 45 degree angle on one, straight on another, or strip some insulation 20mm from the end on another, and carefully write all this down as you go. Cable tie the wires together at regular intervals to keep them neat.

In this next pic, is another excellent way of getting wires through a hole. They are called wiring glands, from 240v elec suppliers, in lots of different sizes. When wires are through, you tighten it and it squashes the wires to make I dust and water resistant. Here I'm using a step drill to get the hole to the required size.


Then poke the wires through and tighten it up;


Ok this gives us our imaginary distribution board, with fuse block, circuit breakers (for external stuff that could temporarily trip in a water crossing, ie anderson plug and electric brake controller) and relays. In the real world you will have separate fuse blocks for each battery, as some items are best run from one or the other, but I'm trying to get the basic ideas across so I'm sure you get the drift.


Continued next post...



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Every dog has his day
nissan
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18,104 Posts
Discussion Starter #3
Ok on the other side of our distribution board we have a pile of wires poking out. Luckily we have written down everything and what each colour wire does (always write down size too, to differentiate same colour in 3, 4 or 6mm).



From here, using our written list, we separate the wires into groups according to end location. This could be groups for; front of engine bay, either side of engine bay, dash, rear of car, centre console, etc etc.


If you want it to be removeable, you can use deutsch plugs on the wiring at the rear. For,example, I made this dash for a mate's a race car, the whole thing can be removed and unplugged in ten minutes or less. Now this dash was wired using ENTIRELY the principles I've discussed above.


Ok next point, split tube and its joins when wires run off to different places.

You've got two or more wires in a split tube, one goes off at right angles, like this.


Poke your sidecutters up the split tube, and make a cut OPPOSITE the existing split, the length of the cutter blade. Separate the two halves, and spread them opposite each other along the continuing section, like this;


Then tape the two tags to the continuing section.

Neat huh?

Or at an angle... Cut a triangle out adjacent to the existing split on each side and tape it like so;




Much neater than other methods I've seen.

Ok one more post I should be done!



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Every dog has his day
nissan
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18,104 Posts
Discussion Starter #5
If you REALLY want to go fully hollywood on the split tube joins, you can buy these for it, but they aren't cheap, and certainly add up when doing a big rewire.



Ok to give you some ideas, I'll repeat a couple of pics I put in another thread, but again these are all done with the same principles above but just on a bigger scale. You could all do this, it's easier than it looks once you've done a couple of smaller ones like our example above.

This was a box with clear cover in a class 2 offroad buggy;


This was a mate's GU patrol, left rear firewall;


This one was in a GQ winch truck on rear cab wall;


This one was a GU winch truck, in V or rollcage behind seats;


This was in between the seats on a class 8 offroad racer, the brains were under the switch panel. Again I used Deutsch plugs so it could all be removed quickly and easily.


And this one was a box with clear cover in my own GQ. Um... Not a quick job this one!



Ok a few points to make.

Wire size.
If in doubt go bigger. Volt loss is EVIL. Thinner the wire, more the volt drop.

You can work out you volt loss with this formula;

Volt drop = length of cable in metres (including earth return) x current in amps x 0.017 (constant for copper) divided by cable area in mm2

To put this in perspective, cable you buy from auto shops is usually labelled 3mm, 4mm whatever. As a rough guide (depending on brand) use the following for mm2 of your wire;

3mm = 1.13mm2
4mm = 1.85mm2
6mm = 4.58mm2
8B&S = 7.5mm2
6B&S = 15mm2
2B&S = 35mm2
0B&S = 50mm2
00B&S = 70mm2

If in doubt between two wire sizes, go the bigger one.
Also remember, if you earth something all the way back the the battery, you have doubled its volt loss. There is NOTHING wrong with earthing it to the body nearby, provided it is a good (preferably) captive nut in body/chassis, and you clean it back to bare metal.

Be aware patrols have woeful chassis to body earth, so if you use the chassis, then you need to add an earth from chassis to either back of gearbox or bodywork somewhere appropriate. You should anyway if it's a GU with factory sub tank.


Ok I hope that helps, if anyone needs anything clarified just ask, but as I've said it is much easier than it looks. Just be patient. All the above jobs I've done have been only with these principles, so no reason you guys couldn't do that too.

Just have a go!



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Pass the Popcorn
Nissan Datsun Patrol
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Brilliant Lee! I'll now be ble to clean up my engine bay with some sort of confidence!

Subscribed for future reference.
 

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Every dog has his day
nissan
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Discussion Starter #8
I forgot to mention regarding volt loss; try to keep it under a third of a volt for most circuits.

Using that formulae, you see that an item that might be ok with 3mm in the engine bay, would need 4mm cable if it was in the rear cargo area.

I've tried to include at least one of all the common things you'll do when wiring your car, if there's anything I've forgotten just ask or if I think of something I'll add it later.

You will find it to be very time consuming. For that reason it costs an arm and a leg to get auto sparkies to do this type of stuff, and to be honest they don't tend to take the care in the neatness that you will in your own car. It's well worth doing it yourself with the above methods or similar.

Hope it helps someone have a go :)
 

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Haha my switches on the dash aren't even labelled, let alone relays which are scattered throughout the vehicle wherever they were easy to fit. Don't know how you ever found the time to produce such a neat setup shown in the last picture, very good.

Excellent info mate, will be sure to use in the future, especially the neat and simple way of wiring up a common supply to a fuse block.
 

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nissan
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Hey Leethal,

Just wondering, with your VD calcs what do you assume for the return path?

If it's wired too and from obviously the copper constand would be used. However my question is more around when using the chassis as the return path. Even though steel isn't as conductive there is a LOT more of it. My thinking is that the actual issue of resitivity isn't the chassis but more over the point and which you have bonded to the chassis. Do you do anything to help resolve this?

Or do you just assume a copper retrun path of the same cross section and forget about it?

Thanks Claydos
 

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Every dog has his day
nissan
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Discussion Starter #11
Hi mate,
I know in physics this isn't entirely correct but for all intents and purposes once you earth it back to the bodywork, provided it's a very good, clean earth, and provided there is a good clean earth from body to battery, then I pretty much disregard it when we're talking the sort of currents drawn from items down the back of the car.
That formulae gives a good generalization that gives you a good idea of whether or not the cable size is ok, and if it makes anyone reconsider and use the next size up then it's done its job, cable can't be too big but can definitely be too small...
 

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nissan
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Couple of quick questions mate.
Firstly what kind of volt drop is acceptable over a circuit?
Secondly, what size breaker do you use for an ARB single pot compressor? I ask because breakers can hold more than their rated amperage for a period before they trip.
and thirdly, where can I get a sheet of ally for the GU left rear firewall like the one in your post 5?

Great post though and has motivated me to try and consolidate all my fusing / relays to a single location.
 

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nissan
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what soldering system do you recommend for this and the general household wiring ?
 

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nissan
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Awesome:bigthumb::bigthumb:
:bowdown:So good of you to dummy up a board for us to see the right way to go about this important part of vehicle ownership.

Rob
 

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This is top notch stuff, use it tomorrow installing my brake controller. Good work Leethal, thankyou for taking the time to school us.
 

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GUII ZD30DI Wgn
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Cool, well done Leethal, I'll add this to the Archives in General Patrol Discussion, Modification section.
 
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