Hi,  I currenty have a marine battery mounted on my trailer that runs my 12 volt lights, curling iron etc.  This battery is not charged off of the truck, it lasts me for a weekend and then I just put the battery charger on it when I get home.  I would like to have 110 installed, lights and 3 outlets, the trailer does not have an air conditioner.  I intend to call the local rv dealer to see if they can do this for me but but before I call I would just like some input.   I have been told that I will need to have a converter instead of a breaker box that would be intended for a house beacuse the breaker box would be unsafe for this application.  The converter is more money of course, i would think that these systems can remain completely seperate for my needs.  Thoughts?  Also, will the 110 wiring need be run in some type of conduit?  Thanks  Joan 

110v doesn't necessarilly need conduit, But it usually requires a heavier gauge wire. Your 12v lights and such are probably running off 16 gauge stranded wire.  Your 15amp 110 circuits will need 14gauge wire and your 20amp 110v will need 12 gauge wire. We usually run conduit to protect the wire in a moving trailer and so we can easily replace any damaged wire with out tearing out the walls.

The simplest option would be to have two electrical systems. Your lights remain on the 12v.  But you add panel with a converter included that provides 110v to the 3 outlets you want and coverts the 110v to 12v to charge your battery.

If you install a 110 v power supply, you can then use a converter to charge your battery, run your DC circuits, and provide several 110 circuits. By using a power center, you can have all the features in one small box. It can have fuses for several DC circuits and breakers for AC circuits.

Any exposed wiring should be protected by conduit or the use of BX cable

http://www.pplmotorhomes.com/parts/rv-converters/rv-power-centers.htm