Licensed Master Electrician in Mass, NH, VT, Me, Ohio, Texas, Arizona, Alaska, Washington, & Oregon. Also UL 508 panel builder, and certified IAEI Electrical Inspector. Electrical is my main gig, Snow cats are just a part time hobby.
The Nickel coated wire can handel siginificantly more current than copper and where it really shines is at the terminations. When I was the head Electrician & Electrical Administrator at WA. Crane and Hoist, I built several hundred overhead bridge cranes, mostly for Boeing and Pac Car(Kenworth). We became a UL 508 panel shop shortly after I hired on. Nickel has an extreemly high melting temperature and doesn't corrode. Regular electrical supply houses don't usually carry it. But in Seattle and other major cities there is usually a place that carries 'Switchboard wire' (Type SIS) and a few others. There is also a line of wire types that have the old cloth insulation with a layer of high temp thermoplastic under it for Aircraft. And there's Teflon coated wire. I like the type SIS and it's not nearly as difficult to strip as the Aircraft or the Teflon. I get it from a place in Seattle called: Hardware Specialities, 206-624-5785.
As a rule of thumb, with Nickel or silver coated wire since the electrons flow on the outside layer, you find that the next smaller guage of wire will handel the same current as a given size of copper. I still use the same sizes, so there's no voltage drop. Voltage drop isn't very siginificant on small machines anyway.
For the Switchboard of my Whitte Generator set I used the Cloth aircraft stuff since I was trying to get a real 1920's look. For the Radio controlled and Infrared controlled material handeling systems at Boeing we used "Destination Wireing" tags. This is a bit too extreem for an ST4. Theese tags have a 6 to 8 digit number, followed by the location of both ends of the wire, on each end of the wire. They have to be computer generated. A typical wire end would be:123456-T1-TB6-123456-T4-TB9. This translates to: Wire Number 123456, lands on Terminal 1 of terminal board 6 at the near end and terminates at Terminal 4 of terminal board 9.
The best thing for cars, trucks, tractors and snow cats is to get ahold of as many colors as possable and forget the fancy tagging system. Make the wires too long, ty wrap them in place(Ty raps are a great improvement over the old wax string I grew up with). Use a minimum of #10 for the wire from the generator to the starter, and for the 2 wires up to the ignition switch and Light switch. I recomend #12 for headlights, and heater fans. Instruments, dash lights, indicators such as turn signal and break lights can be #14. For the Oil temp, and the 2 Idiot lights for the generator and the oil pressure switch #16 is fine.
VW used a green wire for the generator and a blue wire for the oil pressure switch. I pretty much rewired them right like they originally were in the schematic. There are usually (2) #10's that are both "Hot's" going to the dash. One originates from the starter, the other from the generator. One feeds the light switch which in tur feeds several fuses, the other feeds the ignition switch whichin turn feeds more fuses. The wire to engage the starter is unfused.If you have lots of lights and a big alternator these wires can be upped a size to #8 AWG.
Also it is important to bond the transaxel to the chasis with a fairly substantial wire as it carries the return starter current. Xerox the schematic out of the service manual, pin it or tape it to a convienient spot and write in the colors as you lay them in. It's best to loosly assemble the harness like this with the long ends, before you put the transaxel or engine in.
For a snow trac the order of reassembly should go: Brake system first, Harness second, then the variator, less the pulleys, lace some of the wiring, then the drive chains,then the starter, then the engine, terminate more wires, then the exhaust system, terminate more wires, then the variator pulleys, then the air intake induction "horn" and leave the hood off until the very last thing.
Standard wire comes with a temperture rating and a "use" rating coded into the jacket.
- THHN is high temperature thermoplastic that is approved for wet environments.
- MTW is Machine Tool Wiring and is Oil resistant. It's rated 90degrees C and works well for most vehicle applications.
- The SIS wire is rate 190 to 240 degrees C and is probably a bit of overkill. Stay away from wire that is rated 60 Degrees. The engine compartment might exceed this temperature.
Use 'Crimp-on' ends and try to put as few splices in as possible. I generally run every wire as a continuous wire with no splices from the point of origin to the final termination. For Trailers and places on vehicles that I do resort to a 'butt splice' and there is a likely hood that they will get wet I dab "Liquid Tape" on either end of the splice after it has been crimped to seal it up.
