How do RV Electrical Systems Work: A Guide

How to power your RV, different sources of charging your RV electrical system, troubleshooting RV electrical problems, and much more.

How do the electrical systems in your RV work? That is a common question asked by many new RVers. After all, the power system is what helps keep all the modern appliances in your motorhome running smoothly. Whether you own a luxurious Class A motorhome or a Class B camper, a little knowledge of how your RV is wired can go a long way. It can help you understand just how much power you have in your rig and how you can use it without frying the circuits.

Read on to learn more about your RV's electrical systems and how they work.

Types of Electrical Systems in an RV

Your RV basically has three electrical systems installed that help power everything in the motorhome. The electrical systems use both DC (Direct Current) and AC (Alternating Current) to run everything. The AC system resembles the electrical system you have in your homes while the DC system is the one that is used to power normal cars. Since your RV is basically a home on wheels, it needs both systems to perform all necessary electrical functions.

12 V DC Automotive System

The 12V DC automotive electrical system is the one your camper uses to power its engine and external lights (headlights, brake lights, marker lights, signal lights). This system can be found on the chassis on Class A and Class C campers and is powered by a 12V battery that charges when the engine is running. This system is installed in the part of the vehicle that houses the engine, so if you are driving a towed RV, you will need to connect the DC automotive system to the trailer via cables.

Larger trailers require a 6 or 7 wire connection to the hitch while smaller campers can be connected via the 4-wire connection. On larger trailers, the DC system also controls the brakes of the trailer. Note: this circuit is only used to power the brakes and corresponding brake lights on the trailer and cannot be used to power the AC system on the trailer.

12 V DC Coach System

The 12V DC coach system is also installed in the camper and is powered by a battery(s) that is charged by either the DC automotive system or by a charger connected to the rig's AC electrical system. The DC coach system powers a number of applications within the rig including interior and exterior lighting, water pump, heater, blower, and some USB outlets.

The DC coach system is also used to partially power the refrigerator (the rest of the power comes from the AC system and propane). All emergency devices installed on your rig like carbon monoxide sensors and propane leak detectors are also powered by the DC coach system. The 12V DC coach system on your rig is susceptible to being overloaded easily. While you can charge the batteries using an external hookup or a generator, it is generally not recommended to add additional circuits to the DC coach system without the help of an expert.

120 V AC Coach System

The 120 or 240 AC coach system works in the same way the electrical system in a house works. This system powers everything from your TV, AC, microwave, washer, dryer to essentially all plug-un devices including personal use items. The system also powers the hot water heater in your rig along with propane.

You can power the AC system using a 20 amp or 30 amp cord plugged into the electrical hookup at an RV campground. The AC system has a lot more power than the DC system in your rig since the latter is dependant on batteries to run efficiently. If you're plugged into shore power (more on this later) you can install a converter that helps convert AC power to DC power and charge the DC batteries easily. You can also install an inverter that converts DC power to AC power and use the batteries to power up some basic rig electrical systems like the lights and water pump, this can come in handy when you're out boondocking.

How to Calculate Your RV Power Usage

Why do some appliances trip the RV breaker? Are there certain appliances you can't use in a camper? To answer these questions, you need to understand just how much power your rig actually has and how is the electrical system protected.

A regular Class A or Class C camper can easily have a 120-240 AC system with a 12V DC system installed. Smaller Class B campers may have a smaller AC system but the DC system is pretty much the same in all rigs. The electrical system in your rig is protected by breakers (for AC system) and fuses (for DC system). All the circuits within your camper are dependant on a single breaker located on the pedestal you plug into. If the AC system in your rig is overloaded, the breaker trips.

To avoid tripping your RV breaker you need to stagger your use of appliances. As a rule, don't use more than 80% of the amperage of your circuit breaker or circuit. So for example, if the electric outlet on your countertop is connected to a circuit breaker with a trip rating of 15 amp, don't plug in a device that will use over 12 amp of load on it at one time. Apply the same principle on the pedestal circuit.

Here is a table with amp information for common appliances you can use in your rig.

Microwave	13-15 amp
Coffee Maker	5-8 amp
Air Conditioner	12-16 amp
Electric Water Heater	9-13 amp
Refrigerator	5-6 amp
Toaster	8-11 amp
Air Fryer	10-12 amp
Instant Pot	9-11 amp
Hair Dryer	10-15 amp
Electric Kettle	6-12 amp
Iron	8-10 amp

How to Power Electrical Systems in Your RV

Now that you've learned all about the electrical system in your RV, let's move on to how you can power that system. There are many ways for you to power both your AC and DC electrical systems.

Shore Power

Shore power refers to direct AC power that you can draw from an AC electrical grid. Many RV campgrounds and parks have 20, 30, and 50 amp electric hookups that you can use to power your rigs. Larger rigs can be powered by using 30 and 50 amp hookups while smaller campers can use the 20 amp ones. Make sure you do your research on the kind of hookups available in an RV park before you make your reservation. Hooking up to a power source that is greater or lesser than what your RV requires can damage its electrical system.

You can also power your RV by connecting it to a power line coming from a house. To use the line you would either need an adapter or a designated 30 or 50 amp connection. But use caution while doing this, you don't want to blow up the entire system by plugging into the wrong line.

RV Batteries

You can use RV batteries to power up your rig. Most RVs have at least one or two batteries pre-installed. You can also install more if you are going to be off-roading, boondocking, or just traveling long distances. The batteries won't be able to power larger appliances like the AC or heating systems, but they will run the lights, water pump, and smaller appliances for 2 to 3 days.

The RV batteries can be charged using shore power, generators, solar power, and the vehicle engine. A lot of full-time RVers also install backup batteries and keep them charged so that they can be used in case of emergencies or when out camping in the wild.

RV Generators

RV generators are a good alternative to shore power since they also provide AC power to your rig. The size of generator you need depends on the size of your rig and the number of appliances you need running on it. For example, a 1000-watt generator can easily power a camper but will not run appliances like the AC, a 3500 generator on the other hand can power all appliances in your rig.

RV generators might not produce as much electricity as shore power, however, they are much safer when it comes to overdrawing power. If you over-draw power from a generator, some appliances simply won't work. Some motorhomes have built-in generators that are insulated and hence produce much less noise. If you do carry an external generator be mindful of campground etiquette while running it (most RV parks don't allow external generators to run at night). Also, make sure never to run an external generator inside your rig since that can cause carbon monoxide poisoning.

Solar Panels

Solar power is a great way to charge the batteries in your rig. They provide DC power that can be used to charge your batteries indefinitely. The thing with renewable sources of energy is that they still only produce DC power, what that means is you can only run appliances that can be powered by the batteries in your rig. This rules out air conditioning, microwaves, and any other bigger appliances.

However, for smaller campers and adventure lovers, solar power may be a great way to keep those batteries charged and ready to use whenever you need them.

Conclusion

The layout of the electrical system in your RV may sound complicated but the good news is that all the circuits come pre-installed. While you may need to know certain things about RV electrical system maintenance like how to change the breaker and know when a fuse is blown, you generally won't have to do any major repairs yourself. Make sure you carry backup batteries if you plan on camping out in the wild and always carry road safety equipment on your RV travels.