When I got my Muskeg into the shop and removed the engine side panels I was surprised at the size of the wire harness for such a basic machine and shocked by the lack of any fuses. Often I’ve seen old equipment burnt and just wrote if off to the volatility of gasoline. The lack of fuses made me think there are other possible causes for equipment fires.
The oversized harness was a result of every component having its own ground wire, which is a bit of an overkill when considering that the entire machine (such as farm equipment) is primarily steel either bolted or welded together. That said, most wiring problems can be attributed to a ‘bad ground’ so insuring that the engine and battery are properly grounded to the frame is essential.
If you are rewiring a machine consider the addition of a negative cut off switch. The battery is wired to the switch and the switch grounded to the frame. After use, final shut down is to turn off the ground switch; they are relatively inexpensive, easy to install and insure that the power is shut down.
Whether you are just doing some minor repairs on equipment, the installation of a new gauge or component or a total rewire job, basic tools and supplies will be needed.
My wiring drawer includes a selection of meters, nylon ties, fuses, wire and a heat gun
Wire and connectors
Hardware stores and supply shops and some box stores carry basic packs of needed items. I have found that Princess Auto has a good selection of bulk mixed connectors and 25’ rolls of different gauge wire and tools.
Epoxy lined shrink tubing
connectors are aluminum, they break down when exposed to the environment, very much so when exposed to components such as salt. I used this product on a trailer rewire in 1998. This year I rewired the trailer with all new LED lights and wire as the wire loom had began to crack. But when I cut open an ELST sealed connector it was like new. The epoxy seals the fitting of everything. I have found that the best ST is from ‘Brafasco’, the best for my area is ‘Fastenal’ which sell ELST in bulk bags. The ST does what is expected and there is sufficient epoxy that it oozes out properly. The ELST should be adequate size to sleeve the butt connectors and terminals to the wire.
Fuse block/holder
With my Muskeg and airplane I installed a fuse block which uses regular auto fuses (AF). If a fuse blows a corresponding LED light illuminates to reveal same. Inline AF holders and weather sealed ones are also available.
Tools
The primary tool is a wire crimper/stripper. Mine is a better variety and includes cutter, multi
gauge stripper, crimper, re-thread and shear. You could possibly get away with ‘Vise Grips’ for crimping and an ‘X-Acto’ knife for stripping but you may want to invest in some band-aids as well.
Another tool is a heat gun. Hairdryers are not hot enough, cigarette lighters will work fine but too much and everything will burn or melt and if working around gasoline you might burn as well. Note here: the working end of the heat gun gets real hot so beware where you set it down.
Odds and ends
Electrical tape is used for certain insulating duties so a roll is handy.
Nylon ties are also handy to keep the loom grouped and the job neat, this isn’t a fetish it’s safety oriented. Keeping the loom tight and away from hot engine components, revolving shafts and movement that can cause wire chaffing and eventual shorting will prevent problems. Grommets for wires passing through metal is needed to prevent chaffing and shorts, I used an old piece of heater hose to insulate the positive wire to the starter.
Getting started
When I decided to do a re-wire on the Muskeg the other thing that I couldn’t get over was the lack of consistency. Removing the old harness revealed what started out white turned to red and on to green, which really simplified things, so I made my own schematic drawing to make the re-wire work.
When I added an electric fuel pump I started by routing the designated wire from the fuse block to the pump taking care to route it away from obstructions. I attached an insulated blade connector to the wire and a ring terminal connector from the pump to the frame for ground. The other end of the feed was given its own fuse and labeled. This basic step was followed for each wire replaced which allowed me to use designated colours from start to end.
The fuse block I attached was located close to the battery and I energized it with a fuse link. The fuse link was assembled in the following order: ring connector, wire, fuse block, wire and finally a ring connector attached to ignition switch. By doing this I ensured that the wire feeding the ignition was also fused.
When choosing your wire you have to consider that all wire has an amperage (AMP) draw so the longer the wire the more the AMP draw. All electrical components will be labeled as to their AMP draw and if your wire is less than 30’ the following chart is a safe guide as to which American Wire Gauge (AWG) to use for the components AMP draw:
COMPONENT AMP=WIRE AWG SIZE
5-10 AMP =16 AWG
15-20 AMP =14 AWG
25 AMP =12AWG
30 AMP =10AWG
If you’re rewiring to replace old cracked wires or add a component, follow the existing wire loom and replace or add as you go one wire at a time making notes or drawing a wire diagram, and label where each wire is going when it leaves the fuse block. I had to wire my first 8N Ford as it had no wiring on it at all when I got it, but I just followed the original wiring diagram (which was very sparse) to complete the job. As long as you have a supply of fuses and a fuse in place it’s as safe as it gets, the fuse will let you know if you make a mistake.
— Dan Kerr