Ditto on the quality and fitment of the Autosparks harness!  I was really dreading this job, but it turned out to be one of the more pleasurable jobs I've done on the Mini because every wire from the harness terminated at exactly the correct location, and was so well fitted that a wiring diagram was almost not needed.  All of my connectors, relays and fuse/ relay block came from Autosparks, which were cheaper for these things than Radio Shack, and equal or better quality.  They also have the correct bullet connectors and Lucas bullet butt connectors if you want to keep it correct, which I did.  They also helped me choose the right components, wire gauges and quantities for the relay/ fuse block project.  They were great to work with.

Welding cable is basically the same cable.

I have changed a few mini wiring harnesses over the years.  Buying a new harness from Autosparks in the UK is a great experience.  They charge next to nothing to add relays, and all of the wires are in the right spot as you fit the loom to the car.

I can't say this enough:  It fits perfectly, the right wires are in the right place for the right switches and components.  Fitting a pair of relays for the headlamps, and maybe one for the horn or additional lights; if you are into that; is all a person needs to upgrade a mini harness, and they do this for you.  Cheaper than I can drive to the parts store and buy relays.

Note that the mini fuse blocks tend to have multiple wires going to fuses on the load or the source side of things, sometimes both.  A fuse box that has single spades on either side will be disappointing.

So, to recap:  The available replacement harnesses are very well made and do the job perfectly.  If you consider this from an economic perspective, the time and investment plus the quality of the finished product is a far greater sum than some ad hoc adoption of other parts or wiring harness architectures.

It was mentioned yrs ago on this board to replace the battery cable with welding cable. Has anyone had that set up for any length of time?

I ordered a proper black cloth with blue specks wiring harness from Autosparks in the UK.  I also ordered 30 feet of each Lucas color coded headlight low and high beam wire, starter/ main power, horn and fog light wires and a relay and fuse box with relays for each of the above high current draw items. I ran each color coded wire under the dash board on the passenger side to the relay block and then supply wires of the proper colors back to the items to be powered. My relays click on and off every time I turn anything on, but there is no load on the wires in the harness as they are just signal wires, plus all of my fuses are out of sight in a dry, clean environment. The result is a stock wiring harness look, but hopefully none of the typical Lucas gremlins that come with age and a strained wiring system and switches that carry all of the load. 

I wasn't suggesting to replace the main cable with something entirely different, just that if it was the original cable on the car, to consider replacing it if any signs of wear or melting were visible.  It's easy to miss breaks in the wiring jacket, especially where it threads up and over the subframe and through some of the wire clips on the body, so replacing it if possible is a safety measure.

As far as the fuse near the battery, I was on a separate track with my train of thought there.  I was thinking about my stereo amp wiring, which feeds off the battery separately from the ignition circuit.  That's a similar gauge  (4) of wire, but definitely a bit more appropriate for a fuse than the starter cable.  Sorry for the confusion.

OP, the best thing that I've ever doen to any of my Minis was install a new wiring harness in the Moke, second thing was S brakes.

Good luck.

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NavyMini: you didn't mention what year your car is. Many minis have a ballasted ignition system in which the ignition coil normally operates through a wire that has a specific resistance to provide about 9 volts at the coil. When you are starting such a car, the starter solenoid, when activating the starter also switches in a separate wire directly to the coil that has no real resistance, providing 12 volts to the 9 volt coil - a boost of juice to aid in starting and to compensate for the voltage drop when the starter is cranking. When you release the key to the "run" position, the second 12V wire is disengaged.  Both these wires disappear into the loom bundle at the solenoid, but reappear at the coil and are connected to the same low voltage post on the coil, along with maybe a tach feed etc. Neither wire is fused.

Be careful how much current you pass through the ignition switch and associated devices. As has been mentioned, Mini electrical components were originally designed for much different loads than today's car systems. Check your stereo system also for how it should be wired up. Modern systems have at least two power sources - one to control the on-off via the ignition system as you desire, and another much heavier one to provide power to the internal amplifier when it is switched on as well as provide a trickle of energy to keep things like the clock and your station pre-sets. This second one always on and requires a heavier wire fed throuhg its own, much larger fuse. The previous owner probably fed both from a non-switched source. Of course separate amps will also need their own supplies and protection.

While that one big cable certainly has had lots of failures over the years, what do you propose as an alternative?  Rather than implementing a different main cable, adding additional clamps and clips to secure what is already there should be sufficient.

Fusing on the main cable?  I don't see how.  That main cable has to support more than the power while the car is running.  More importantly it has to support the current draw of the starter motor.  I don't have figures to quote but I anticipate that there will be too much current for a typical fuse or breaker.

As mentioned, our host sells new harnesses.  If however you are enthusiastic about making a harness yourself, it would benefit future owners if you follow "standard" Lucas wiring colors.  That wiring and many of the supplies you will need are available from Britishwiring.com.  If you really want to use blade fuses, remember that the rule of thumb is to multiply the "Lucas" fuse rating by about 0.6 to determine the closest equivalent blade/US type fuse.  (i.e. a 35 Amp Lucas fuse would be 35 x 0.6 = 21 Amp so you would use a 20 Amp blade fuse). 

If you want to upgrade the electrical system of your mini to handle higher loads and additional electrical devices then a new wiring setup can simplify things.  Unless you are amazingly efficient, rewiring even as simple a car as a mini will probably take a bit more than one day though. 

First things first, a basic mini wiring system should have one fuse block on the firewall or side of the engine compartment, and up til 1980-something minis, either four or two fuses.  It's not a system built to handle large stereo amplifiers, or even modern quality headlights/driving lights, so external turn-on relays are as important as the fuses if you have added greater draw devices.

If you are upgrading to a new wiring loom/fuse box, then the main battery cable from the battery in the rear to the starter relay in the engine compartment should be one of, if not the first thing you should replace.  There is no greater potential for an electrical fire in a mini than that one large cable threading through body panels and past the exhaust.  I would recommend adding a large fuse/breaker right next to the battery as well.

You may want to check out Painless wiring, //www.painlesswiring.com/ for car specific wiring harness replacement, instead of putting in something built for a boat with several fuses in the 1 to 5 amp range.  Almost nothing on your car save a low end stereo head unit will be able to use such low fuse points.

Our host sells new wiring harnesses correct to minis and those for later model (four fuse count, pre-fuel injection years) have a switched 12 volt feed off the ignition that is great for teeing off your stereo and accessories right at the fuse box.

Since I have been dealing with indicators, stereo and other assorted electrical problems, I have decided to take a look at the wiring as a whole. I have discovered that I am going to have to fix a LOT of the previous owner's "fixes" and "modifications". I am going to repair what he did with the fuse system first. He replaced the old school style cylinder fuse panel with a bunch of individual in-line blade fuses. Annoying and wrong. So, I am going to fix a brand new blade fuse PANEL to replace the whole thing. I found a nice panel on Amazon.com for cheap that has 12 fuses holders, a primary fuse and lables. It'll work GREAT! Here's the problem. The wiring on the old Minis has the primar battery cable going straight to the starter and then branching off into a bunch of 12-gauge and 10-gauge wires to the systems individually, while all modern cars (and this new fuse panel) use a single primary 12 volt and then branches off into the different systems within the fuse block. What do you think about running a new primary constant 12 volt cable directly into the fuse box and branching the systems off that and then chop the small wires off the starter cable. It'll take about a day, it'll clean up the engine compartment, it will be much more effecient and easy to locate blown fuses and I won't have to worry about wet fuses or old nasty wires ground out somewhere. This will go along with my interior rebuild. 90% of the constant 12 volt wires will be replaced, so there will be a lot of soldering, crimping and running wires as well as patching everything back up with cable run covers. I am also thinking about putting in a smaller fuse panel for the key-on 12 volts (so my stereo will actually turn off on it's own. What does everyone think? Is it worth it? Am I going to effect any of the systems (all 3 of them) by running a primary instead of a branched 12 volts? Has anyone done this and can give me tips or pictures?

Follow the link below for the primary fuse panel.

//www.amazon.com/gp/product/B001P6FTHC/ref=ox_sc_act_title_6?ie=UTF8&smid=A1UNWS4MSNTF2A