# How to Wire an Electrical System in a Camper

by John Cagney Nash
rocky mountains image by Melissa Schalke from Fotolia.com

Wiring a new electrical system for a camper requires the installation of two separate systems. Both are 12 volt. There is a chassis system, which functions just like a regular automobile, and a coach system, which serves the "house" functions. It is also possible to wire a 120-volt system to work like a normal household installation. Many options for provisions and product choices are available, so considerable forethought and research should go into planning the project before beginning any work.

## Create a detailed plan, then install

### Step 1

Plan what the 12-volt coach system must provide. All interior lighting is typically powered by the coach battery, as is a circuit of power outlets. There is almost no limit to the optional equipment that can be installed. Manufacturers make 12-volt refrigerators, space heaters (which employ electric air movers even when they burn propane), entertainment systems, water pumps, even powered cargo bays that open at the touch of a button. Slide-outs that make internal space much more accommodating all work using 12-volt electric motors.

### Step 2

Determine the provisions necessary to run the 12 volt chassis system so it is self-sustaining. There must be an alternator which generates power and a battery which stores that power. There must be a fuel pump to supply the engine with diesel or gasoline. There must be a horn, brake lights, turn signals, side lights and marker lights if the camper is to towed on the road.

### Step 3

Calculate the physical size and amperage capacity required of the 12-volt fuse boards that will protect each system. Calculate your predicted peak coach needs and purchase a deep cycle battery (or bank of batteries) capable of answering that demand. Purchase a Starter Lights Ignition (SLI) type battery for the chassis system.

### Step 4

Decide whether you will require a battery isolator, an inverter and a converter. An isolator directs power generated by the alternator to the chassis battery until it is fully charged, then redirects the power to the coach battery, and prevents the coach system from draining the chassis battery when the engine is switched off. An inverter produces 120-volt power from 12 volt power, so you can use household appliances like coffee makers and hairdryers. A converter does the opposite when the camper is plugged in to a shore power hook-up, and, a converter charger also automatically recharges the coach battery.

### Step 5

Decide whether you want a 120-volt system, an on-board generator, a tow package or a solar power array to keep your batteries charged while camped.