June 7, 2012

Electrical Setup and Wiring

In the last post I worked out what our electrical usage would be based on the fixtures we would be installing and things we might be plugging in.  From this we determined we would be using two 20 watt solar panels that would be mounted on the trailer roof.  The electricity generated from the panels would then be 'stored' in a deep cycle marine battery which we still have to purchase - we just need to figure out which one. 

The power coming out of the battery is D/C current so we made sure that all of the fixtures (lights and fan) could run off of this without needing to be converted.  We also decided to keep things simple by installing 2 auxiliary ports in the trailer, one inside the sleeping quarters, the other in the galley.  These ports are the same type you would have in your car (the cigarette lighter type).  With these we can power most of our auxiliary equipment (e-reader, cell phone, laptop, etc.) with either a lighter plug or with a special inverter like this:

auxiliary inverter
installed auxiliary port in the galley

I also had to accommodate for the trailer running lights as well since they would be running off of the a plug attached to the car at the hitch.  What is nice about this is that there are numerous resources online to help you with trailer wiring.  There are also complete wiring kits for the brake lights you could purchase to make things even easier - ours came with the trailer frame we bought at Harbor Freight, so we saved the wires.  In a standard trailer like ours, we have 4 wires that run everything (break lights, turn signals, side marker lights, etc.), in our case these are Yellow, Brown, and Green.

I then decided on the color code of wiring to use throughout the rest of the trailer.  I decided to use red and white for all of the 12 Volt wiring as this is what I have seen in the past on cars and trucks. red would be the "hot/positive" and white would be the the "ground/negative".  All wiring is 16 gauge which is a bit overkill since the voltage and amperage on each item is so low, but I figured since we would never see the wires again after the roof was skinned, better safe than sorry.  I utilized about 200 ft of each color on the whole trailer since everything is running from each item back to where the fuse box will be in the tongue box (in both colors).  The last thing we wanted was another ground issue like we had with our first wiring job!

Simple Wiring Diagram

To feed all of the wires, I drilled holes on each side of the trailer through the center of each spar.  This acted as my wire chase to go to any place I would need within the trailer.  Normally I would have put these wires through the walls and on the underside of the trailer, but since we already buttoned up everything, this was the easiest method.  However, since we had yet to finish skinning the wall between the cabin and the galley, I was able to run wires for both auxiliary ports in this area by shaving away at the insulation to embed the wires.  That way they will be hidden when we finish the wall.

After all the wiring was installed, I checked the impedance of each wire group by connecting one end together (white to red) and testing the circuit with an ohm meter on the other.  This ensured that there were no tears in the shielding or breaks in the wire.  I should also mention that I labeled each wire group with the name of the fixture/outlet it was going to so we could keep track of everything - I cannot stress this step enough!!

note the explosion of wires

The galley hatch was a bit harder in the fact that we wanted to make it removable even after the trailer was completed.  To do this I added connectors at the hinge section so that we could literally 'unplug' the hatch before taking it off.  The wiring on the hatch was a bit easier in the fact that most of the were from the trailer wiring (break lights, license plate light, turn signals).  One thing I also did was to combine all of the ground wires from each light to a terminal block.  This meant that we would only need one white/ground wire back to the hitch connection.  The one item to tie back to the fuse box was the light for the galley.

running ground wires to the terminal block

While all this wiring was going on, we decided to install the lights we purchased for the cabin.  We located and installed these, pulling the two wires through the wall and attached them to the wiring I had already run.

Getting all the wiring done took a lot of prep work and thinking though, but will definitely make the trailer a more comfortable home for our travels.  Now we just need to get the fuse box and solar panels figured out!

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