Tuesday, 23 July 2013

Electrical Work

I spent about a week messing with the electrical system, including planning and execution.  In its original state, this Boler had a 120 volt system for the interior, and it had the usual 12 volt running and signal lights connected to the tow vehicle through a 4-wire connector.  My new system includes a charger/converter and a number of 12 volt fixtures for the interior.  So I actually have three systems on board: the tow vehicle-controlled 12 volt system, the battery-powered (charger-powered) 12 volt system, and the 120 volt system.

My charger/converter, located below the front bench.

My new axle includes electric brakes, so right there I had to switch from a 4-wire trailer connection to a 7-wire system. My Honda van already had a 7-wire hook-up so that was no problem.  I had already decided on locating my charger/converter below the front bench, next to the door. I bought a length of cable and a trailer-end plug, and brought it through a hole in the front floor alongside the frame.  I used a terminal block to make connections between the interior lines and the cable to the tow vehicle.  I had a length of 6-strand cable salvaged from the original wiring, which I used to extend the running, turn signal and brake connections to the rear of the trailer.  And I used a bit of salvaged heavy-gauge 3-strand cable to go from the terminal block forward to the battery.  The converter and the terminal block are mounted in such a way that they are kept separate from the contents of the front bench storage space, although I will be able to pull the whole thing into the open space below the right hatch if I need to get to it.  The vent fan of the converter will be up against the bench wall -- I will cut a circular hole in the wall and put some sort of a grille over it.  Maybe an automotive speaker grille.

This shows the terminal block and the 120 V connection
The 120 volt system was pretty straight-forward. I cut a hole in the sidewall of the trailer next to the refrigerator vent and installed a "motor base", which is an odd name for a standard U-ground male connection port.  It fastened neatly to a rectangular receptacle box below the sink, which I used then as a junction box. One line went to the outlet box at the front of the lower kitchen cupboard (which I think was standard on all Bolers), and then branched off to outlet boxes in the two dinette benches.  Another line went to an outlet box in the fridge space and then on to the charger/converter beside the door.  I installed a new outdoor receptacle in the exterior wall, just above the wheel well, inside the closet.  
Here is the back of the fridge with its 120 volt and 12 volt supplies.
I used lengths of plastic "split loom" to keep all my wires neatly contained.  Because the body of the trailer is fiberglass, ground wires had to be run from each fixture.  I chose to run separate ground lines for some circuits, which meant that I was using two strands of primary wire for each.  In a few places I used small plastic hooks, fastened to the fiberglass interior wall with double-sided adhesive tape, to keep the cable looms off the floor, and to keep primary wire close to the walls.
Wiring for the right brake/turn light, and side marker.
Here is the left brake/turn light.
If you look closely you can see the small plastic hooks.
An LED light fixture, flush mounted to the closet wall.
In most places I used Marettes to make my 12 volt connections, but they end up being pretty conspicuous.  I think they'll be less so once I have shelves inside the closet.
"PowerFist" LED tail/brake/signal light from Princess Auto.
Exterior "porch light" -- the wiring is inside the closet.
Beside the water inlet, I mounted a 120 volt outlet.
One tricky thing about the wiring was keeping the positive and negative 12 volt lines straight in my mind.  In residential wiring, the black wire is "hot", but in most 12 volt automotive systems, red is hot (or positive) and black is used for the ground.  I had bought 100 feet each of red and black primary wire thinking that it would help me to be consistent.  But some of my lights had black and white leads.  I ended up with several black-to-white connections and black-to-red connections.  Just in case, I attached tags to some of the wires to indicate polarity.
If I have time tomorrow, I will connect the trailer to the van and see if the brake and signal lights work.  I can't install the dinette benches yet because I haven't finished the plumbing that runs beneath them -- so I can't finish the 120 volt connections and test them yet.  The plumbing is next.



  1. Great blog! Very informative and easy to follow. I was wondering where you purchased your porch light from, I've been trying to find one and coming up dry.

  2. Hello! I have a question regarding the power supply for early 1970's Bolers. Was there no factory option for 12V?

  3. Hmm. I really don't know if there was a factory-installed power converter back then. Sorry I'm no help to you.
    And sorry for the delay in responding to your question -- I've been neglecting the blog for quite some time. But I think it's about time I got back to it.