There's a lot of public information about power distribution in the teardrop trailer, but, seemingly, not so much information on designing a high-quality underbody wiring harness to run your marker, clearance, license, and stop/turn/tail lights. Not that I have all the answers! I'm still learning.
I've played around with different methods.
- I've run surface-mounted wiring inside the camper using Legrand's Cordmate II raceway system. Looks pretty. Works well. Easy to spend several HUNDRED dollars on a full system.
- I've done the Harbor Freight thing and just run bare jacketed wire along the inside of the trailer frame, attached it with wire clips, nutted all the connections, and hoped to God it survived!
- I've run wiring through metal conduit welded/bolted to the trailer frame. Very clean, very safe, but not very accessible or versatile. I prefer to standardize my designs; I don't want to be installing new conduit every time I shift the axle location or add electric brakes.
So I've moved towards an automotive-style wiring harness where all the wiring (16 gauge) is encased in polyethylene split loom and no connection is left exposed to the elements. The wiring harness was held to the inside of the trailer frame with adhesive-backed nylon loom clamps. Butt connections were made with heat-shrink crimp terminals. Other connections were made with quick splices or T-taps (I use LED lights, so I don't need much metal-to-metal contact) and then encased the terminal in a Tee connector. The Tee connectors were really nifty, but I could only get one terminal to fit within one connector. The trailer connector was a 7-way trailer connector completely encased in molded plastic - very rugged! The connector went to a 7-way trailer screw terminal junction box mounted on the trailer tongue, which then delivered power to all the components. Oh, and I ran a separate ground wire rather than using the trailer frame as the ground.
That system worked fairly well, but the Tee connectors were a pain. And I started to worry about the adhesive-backed clamps on the paint - even though they did have quite a grip! So my latest addition is to use plastic junction boxes at every trailer light. And to use standard vinyl-coated loom clamps to hold the wiring harness, connected to the trailer frame using either Christmas Tree panel fasteners or nylon snap rivets. No screws to rust or vibrate loose.
So, that's where I'm at. I feel like I'm getting close to a rugged, weather-proof system that is versatile enough to be used for any camper, big or small, with reliable heat-shrunk connections and easy access in the future. Still chipping away at the details.
What other systems do you use? Anything to add/subtract from mine?