Hello Matt; I read all of the responses and thought I'd chime in as well. I think that everybody has you pointed in a good general direction, so perhaps I can help get to some specifics and recommendations. When I rewired both of my airplanes, the first thing to go was anything what wasn't teflon. In the KR2, that was about 95% of the wiring! The airplane had been constructed by an aerospace engineer (and former Navy fighter pilot), so the attention to detail about the mechanics of the airplane was outstanding. However, attention to the electrical portions were sadly lacking --- I found cheap (plastic coated) wires everywhere, ALA Home Depot, which IMHO is clearly unacceptable for an airplane.
All wiring was replaced with teflon insulated wires, the size according to the anticipated load X2. For electronic instrumentation, I used mostly 22ga. Where practical, I used 28ga. wiring, specifically for audio wiring behind the panel, etc. Anything other than audio or electronic instruments received at least 18ga., and for audio that needed to be routed to the headsets or the rear speaker, I used 24ga. For example, the wiring to the T&B gyro is 18ga, the wiring to the radio is 14 ga., the wiring to the wing strobes is 14ga. (with shield). The wiring to the rear clearance light is 14ga., and the wiring to the utility outlets is 12 ga. The wiring to the main buss from the battery is 6ga., and the wiring from the main breakers is all 10ga., everything teflon. All wiring is color coded. One of the biggest maintenance problems in certificated aircraft is that nearly all of the wiring is white. This is simply a nightmare, so I avoided it by going with common-sense colors. It made a world of difference when tracing circuits! As for coax, I wouldn't get mired down in losses. We are talking about 10, perhaps 20 feet of coax, and worrying about losses per 100 feet is a waste of time as it will measure out to mere fractions of a decibel. I would focus on 50 ohm coax that approximates RG-58 diameter. During my upgrade, my focus was purely on avoiding coax such as the RG-58/LMR series, as these are standard poly. type cables and offer no fire resistance. Everything I installed simply mirrored the stub. cable examples that came with the various radios - double shielded teflon coax. Of all of the cables available, my favorite is RG-142 B/U. It is plenum rated, double shielded, and is what you will find as commonplace in the commercial aircraft industry. It fits "standard" fittings, and is what you're going to find if you investigate "standard" aircraft communications coax. It averages about $1.00 per foot. Yes, where practical, keep audio, data, strobe and power wiring separated. If it isn't realistic to separate the wires, then consider using shielded wiring, or at a bare minimum, twisted-pair wiring. For my marker lights and anything over about 2 feet, I used a drill and created twisted-pair wiring. This is a "pseudo shield", and well worth the effort. You will find that there will be basically two culprits - one of them will be the use of non-shielded wiring over long runs, and the other will be dealing with the strobe lights. As before, simply create a twisted-pair to deal with the first problem --- All of my wiring has this as a minimum, even if it is to a utility outlet. The second one - the strobes - needs special treatment. You're dealing with VERY high voltage here, and spikes as well. I would go with a shielded teflon cable. Very important is that the shield be grounded at ONLY one end. In my installation, I simply grounded the shield at the battery, and left the end at the wingtip taped off. If you ground both ends of the shield, you are asking for all sorts of interference problems, not to mention the proverbial "ground loop" problem where when the strobes fire, the radio burps, or you have a continual hum in the headset and even turning everything else off doesn't solve the problem. In my installation, I used a twisted pair from the battery to a distribution system. From there, I created a ground buss, and various power busses, each breakered separately. All wiring is contained inside of individual cable management plastic shields. I further identified each "bundle" by using colored cable ties. Hope this helps. Dave.
