How to Wire Inverter To RV Breaker Box


Knowing how to wire an inverter to an RV breaker box allows for efficient electrical power utilization when camping or traveling in an RV.

Wiring a power inverter to your RV’s breaker box involves creating a connection between your battery bank, inverter, and RV’s breaker panel, often using changeover switches.

These switches enable seamless transition between shore, generator, and battery power, ensuring a consistent and safe electricity supply for mobile adventures.

In this article, we will simplify the process for you, explaining step-by-step how to install an inverter to your RV’s breaker system properly.

Step-by-Step RV Inverter Installation Guide

Before installing an RV inverter, know the safety protocols for working with electricity. If you’re not comfortable doing this, consider hiring a professional.

You will also need to gather the necessary tools – a multimeter, wire stripper, screwdriver, drill, and the appropriate wires and connectors for your specific inverter, battery bank, and breaker box.

Step 1: Setting Up the Inverter and Battery Bank

Select an optimal location for your battery bank and the RV inverter. To minimize voltage drops, keep them close together.

The chosen area should be free from moisture or excessive heat, well-ventilated, and easily accessible for maintenance or troubleshooting.

Secure the batteries and the inverter in place, typically by fastening them onto a suitable substrate like a wooden board or metal mounting bracket.

Step 2: Connecting the Inverter to the Battery Bank

Connect the batteries to the inverter using DC cables to create a DC power circuit.

First, use a multimeter to verify the polarity of the connections. The positive terminal on the battery should connect to the positive terminal on the inverter and vice versa.

Secure the connections and ensure the cables are safe from any potential damage.

If using multiple batteries, ensure they are arranged in the correct series-parallel configuration to provide the correct DC voltage.

Step 3: Connecting the Inverter to the RV Breaker Panel

Depending on the available electrical power supply options, several methods exist for connecting your battery inverter to the RV’s electrical system.

You can establish a direct connection or install a 2-way or a 3-way changeover switch.

The switch (a transfer switch) allows safe alternation between shore power and battery power, preventing back feed into the power grid – a potential hazard.

Installing the Inverter Directly

For a direct connection, strip a small insulation section from your wires.

Next, attach the positive (red) cable to the positive terminal of the main breaker on the RV breaker panel and the positive terminal of the inverter output. Don’t forget to install a fuse box on this positive wire.

Similarly, attach the negative (black) cable to the main breaker’s negative terminal and the inverter’s negative output terminal.

Installing a 2-Way Changeover Switch

To 2-way changeover switch can help you quickly switch between shore power and inverter. To install a 2-way changeover switch, do the following:

Start by connecting the live and neutral wires from the inverter output terminal to one of the input terminals on the switch.

Next, connect the AC power supply from the shore power source to the other input terminal. Use a circuit breaker box for safely connecting shore power to your electrical systems.

Wire the output terminals of the switch to the main breaker of your RV breaker box. Ensure that the output from the switch is connected to the input on the breaker box.

Finally, connect the ground wire to the ground terminal or the body of the changeover switch.

Installing a 3-Way Changeover Switch

If your RV has three potential power sources (AC shore power, an AC generator, and the inverter), you’ll need a 3-way changeover switch.

  1. Begin by connecting the power from the AC shore power source to input 1 of the switch.
  2. Connect the AC power from the generator to input 2.
  3. Then, connect the AC power from the inverter to input 3.
  4. Wire the AC output terminals of the switch to the main breaker of your RV breaker box.
  5. Ensure the power from the AC shore power source and the AC generator is channeled through their respective circuit breakers.

The inverter wiring diagram is shown below:

Installing a 3-way changeover switch with AC shore power, AC geenrator and an inverter

Step 4: Setting Up the Battery Charging System

If your inverter includes a built-in charger, connect it to an external AC power source, such as a wall outlet. This arrangement allows the inverter to charge the batteries while connected to a shore power socket.

In cases where you have a separate battery charger and not an inverter/charger, you can still utilize an AC shoreline or an AC generator to charge your batteries. But you with need a converter for transforming AC power into DC power.

To easily switch between shore power and the generator, use a 2-way changeover switch.

You can also use solar panels to charge your batteries. In this case, you’ll need to connect the solar panels to a solar charge controller and then link the controller to the battery bank.

Ensure you install a fuse on the positive (red) wire for safety. Use this calculator to determine the right solar system size for your requirement.

The wiring diagram for a separate battery charging system is shown below:

Wiring diagram for a separate battery charging system

Step 5: Powering On the Inverter and Testing Your Setup

After wiring the inverter to the breaker box and connecting the battery charger, it’s time to turn on the inverter. Ensure all connections are secure before doing so.

Switch the inverter on and ensure everything in your installation is functioning correctly.

Start by confirming whether the voltage on the DC system matches the inverter’s requirements. Next, switch on the breakers individually, checking each circuit’s functionality.

Finally, we want to test the system on AC load. Simply plug in your air conditioner or other AC appliances to test the system on the actual load.

Remember, this process can be complex, and the specifics can vary based on your particular RV, inverter, battery bank, and breaker box.

Always refer to the manufacturer’s instructions and consider consulting with a professional if needed.

Understanding the Complete System

Electricity flow in RV electrical system

The RV electrical system operates through three primary sources: AC shore power, an AC generator, and a solar system.

The solar system generates DC power, which is managed and regulated by a solar charge controller before being used to charge the battery.

The AC shore power and AC generator also contribute to battery charging. However, since these sources produce AC electricity, a converter transforms AC into DC power, suitable for battery storage.

When the power from the battery is required, it must be converted back to AC before entering the RV breaker box. An inverter facilitates this conversion, changing DC power from the battery into usable AC power.

To effectively manage these power sources, a 3-way changeover switch is installed.

This switch allows seamless shifting between the AC shore power, the AC generator, and the inverter. This ensures efficient power management within your RV system.

Selecting the Right Wire Size for your Inverter

Choosing the correct wire size when wiring an inverter to your RV’s breaker box ensures safety, functionality, and efficiency.

The proper wire size will depend on several key factors, such as the output of the inverter, the distance from the inverter to the breaker box, and the amperage of the circuit. Follow the steps below to make the correct choice:

Determine the Current

Start by determining the current that the inverter will be producing. This information is usually stated in the product’s manual.

Alternatively, you can calculate it by dividing the inverter’s output power (in Watts) by the input voltage (in Volts). For example, if you have a 2000W inverter that supplies 230V, the current would be 8.7A.

Account for Power Factor and Efficiency

Next, consider the inverters’ efficiency and the AC circuit’s power factor.

Assuming a power factor of 0.8 and an inverter efficiency of 90%, the current flowing through the wire would increase to 12.1A.

Add Safety Margin

Next, add a safety factor to your calculations. This will cater to unexpected overloads, inefficiencies, or potential expansions in the future.

A margin of 25% is a good starting point. With this safety factor, the current for the example above will increase to 15.1A.

Select the Correct Wire Size

After finding the maximum current that will pass through the wires, refer to a relevant wire sizing chart to determine the required wire size.

These charts list the safe carrying capacity (in Amps) of different wire gauges under various conditions.

Always choose a wire size that can safely carry the maximum current that your inverter will produce. The American Wire Gauge (AWG) wire selection chart is given below:

American Wire Gauge (AWG) wire selection chart

The chart lists two types of wiring configurations: chassis wiring and power transfer.

The chassis wiring arrangement typically involves individual routing of each wire. This differs from power transfer wiring, in which wires are laid out in bundles.

Therefore, chassis wiring allows for superior cooling, resulting in the wires carrying more current.

For the above example, the minimum AWG gauge needed is #18 for chassis wiring and #9 for power transfer.

Verify the Voltage Drop

If the distance between your inverter and breaker box is long, you may need to choose a larger wire size to compensate for the voltage drop. As a rule of thumb, aim for a voltage drop of less than 3% for the AC side wiring.

To calculate the voltage drop in wiring, read the resistance (Ω / km or Ω / kft) from the table above. The voltage drop is then calculated as follows:

\(V = \displaystyle {\frac {I*R*L\ (m\ or\ ft)} {1000}}\)


V = voltage drop (V)

I = current in amps (A)

L = wire length in meters (m or ft)

R = Wire resistance (Ω / km or Ω / kft)

For our example, the resistance of the selected AWG#9 wire is R = 20.948 Ω / km.

Assuming a wire length of L = 2 m, the voltage drop can be calculated for current I = 15.1 A is V = 0.63 V, which is just 0.28% of 230 V.

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