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How Does an RV Automatic Transfer Switch Work – Explained

Written by Philip Lopez / Fact checked by Paul Lemaire

how does an rv automatic transfer switch wor

I like to keep my appliances running even when I’m not plugged into shore power. Someone recommended that I install an automatic transfer switch. So, how does an RV automatic transfer switch work?

An RV automatic transfer switch selects between two inputs- shore power and generator – to power your rig. Basically, it makes it pretty easy as you never have to switch between two inputs manually.

Let’s find out more about this powerful electronic device below.

Table of Contents

About RV Transfer Switch and Its Operation

An RV power transfer switch is an electronic device that selects the AC input power source into your RV. When you’re not plugged into shore power, you can run an AC power from an onboard generator.

You probably have an automatic transfer switch (ATS) if you have a built-in generator. This particular device chooses whether to take an AC input from your shore power or generator.

Most of the time, it prioritizes generators, meaning that it will drop the shore power connection once the ATS detects the power of your generator.

A normal transfer sequence includes:

  • When your generator is on, it automatically selects AC input power from your generator.
  • Within seconds, the generator starts supplying electricity to your RV.
  • It will default to shore power input if the generator is off; this is your 120-volt AC input. You should be able to hear a click sound when you hook into shore power.

Only one input can be linked at a time to prevent any electric hazards. Expect a delay to let the generator warm up a bit before powering the heavy loads.

Types of Transfer Switches


There are two types of transfer switches: for portable/small generators and for large generators.

1. Portable/Small Generators Transfer Switches

Some RVs have portable and small generators. This type of RV generator transfer switch can deliver power up to 21,000 watts. It isolates selected circuits from the RV with two switches, each having three positions- utility (shore power), off, and generator.

To switch power from utility to generator, it passes through the OFF position to prevent short-circuiting that might pose a fire hazard. In some models, they incorporate circuit protectors to prevent overload.

2. Large Generators Transfer Switches

These switches transfer automatically. They come with nice features, breakers, and fuses, making them safer to use for large RVs. This type offers great flexibility as it can manage different voltages.

In some models, special switches are built to allow the use of multiple generators. They have an OFF option to prevent the generator from starting automatically.

The RV Transfer Switch Location


The ATS is located near the front of the breaker panel. If you have no idea, follow where the shore power cord enters the RV because it’s somewhere near that area. It’s that metal or plastic box where the generator and shore cord are connected.

While the shore power cord is linked to one of the inputs, the generator is hard wired to the second input of the transfer switch. Turning the generator on will close the relay contacts and transmit the generator power to the main panel.

For my 2005 Daybreak 3270, the ATS is located behind the power cord compartment.

Safety Tips in Using ATS

  • Turn off your thermostat before starting your generator to reduce the current load.
  • To protect your RV from bad power, we recommend installing a surge protector on the transfer switch.
  • Get the same size transfer switch with your RV. If your RV service 100 amps, use a 100-amp transfer switch to prevent overload.
  • Check your ATS for any loose connections, dirty contacts, wiring cuts, or any visible damage regularly. Ask a professional to fix these damages.
  • Keep the ATS away from moisture as it can damage the system or may cause electric shock.


Now that you know “how does an RV automatic transfer switch work?”, you can learn how to value this electronic device. This device switches power between the generator and shore power, whatever is available, ensuring the constant supply of electrical power on your RV.

The best part is that the power switch is made automatic for your convenience.

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