Trailer Wiring Ideas

Even if you run a hot and ground to every fixture, they still have to be tap-spliced in somewhere since theres only one of each coming from the tow vehicle. I ran a dedicated hot(tail) and ground all the way back on each side and tapped in as necessary. I didnt trust grounding to the frame of the trailer. The only place you'll have to use butt splices are at the harness and the tail lights.

Definitely dont skip the heat shrink. Get the adhesive lined stuff that waterproofs the connection. They also make butt splices with the adhesive lined shrink material built in. For the tap-splices, I got the ones that are supposedly waterproof- they were filled with some sort of goo. Also make sure you use good quality tinned wire. I oversized mine a bit (14 awg).

The worst connections that I found happened to be inside the connector that plugged into the tail lights. For $10-15 each, I highly recommend replacing the whole light and connector assembly.

My install could have been a little cleaner. I suggest making the connections at the tail lights first, and running all the wires to the front (cut them long). Move from back to front, tap-splicing and adding service loops as you go (I put one at each tail). Tighten everything down/together with zip ties. The last step would be to make the connections at the tongue: the tap splice for the tail lights and the butt connectors for the 4-pin harness. I left a small service loop at this end as well.

Service loop = Outstanding idea.

Tim, could you be a little more specific? I'm still a little hazy on what parts to use.

I just cross my fingers and if that doesn't work, kick the lights until they come on or fall completely off!

8122pbrainard wrote: 1.On my channel frame trailer I ran 1/2" pvc pipe as a conduit to protect the wiring. I have a tubular frame that this wasn't required.

Pete, the tubular frames Ive seen do get water in them. I have a channel and thought of using conduit, but I figured it would do a better job of holding water in than it would keeping it out. How do you keep it perfectly sealed?

TRBenj wrote: 8122pbrainard wrote: 1.On my channel frame trailer I ran 1/2" pvc pipe as a conduit to protect the wiring. I have a tubular frame that this wasn't required. Pete, the tubular frames Ive seen do get water in them. I have a channel and thought of using conduit/PVC, but I figured it would do a better job of holding water in than it would keeping it out. How do you keep it perfectly sealed?

Tim and Doc, The conduit is to protect the wiring from physical damage like getting ripped off the trailer and not to protect it from moisture. It is open at both ends (no fittings) and in the middle where wire is branched to clearance lamps. Insulation and integrity of splices are there for moisture protection. Wire is run underground and in water all the time. You may have a 40KV underground line through you back yard.

Doc, I'd rather have the wire sliding around the inside of the low coefficient of friction pvc pipe that the rough inside of a steel tube.

Pvc pipe to protect wiring.


Another picture. This trailer I did not use marine grade wire and haven't had a problem since I rebuilt it 27 years ago. I have smashed a tail light on a stump though!!


The one hole conduit clamps I was even able to find in aluminum. No rust.

That's a lot of work.

The Dude wrote: That's a lot of work.

Not if you divide the work by the 27 years (and still going) of life I've gotten out of good wiring practices.

In the most recent Trailer Boat there is a nice article about building a simple light bar. It is worth a look - and sure to keep your lights out of the water.