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RV Electrical System [with Schematics and PDF]

DISCLAIMER: AS AN AMAZON ASSOCIATE I EARN FROM QUALIFYING PURCHASES. THIS POST CONTAINS AFFILIATE LINKS THAT WILL REWARD ME MONETARILY OR OTHERWISE WHEN YOU USE THEM TO MAKE QUALIFYING PURCHASES. FOR MORE INFORMATION, PLEASE READ MY EARNINGS DISCLAIMER.

RV’s electrical system consists of a 120-volt AC circuit (that is powered by shore power or battery power through the inverter) and a 12-volt DC circuit, which is powered from the battery, or shore power through the converter. RVs are generally wired for two different types of services, 30-amp, and 50-amp.

Direct Current (DC), Alternating Current (AC), and chassis (or vehicle) power are the three main electrical systems in your RV. The chassis power system is connected to the RV electrical grid and controls all vehicle-related power gadgets, lamps, etc.

DC (or Direct Current) is an electrical charge that flows in only one direction and is commonly used in electronic devices. It’s the same type of energy that is stored in your RV’s batteries.

Applications of DC power include:

  • Charging batteries
  • Automotive applications
  • Aircraft applications
  • LED lights
  • Solar cells
  • Computers
  • Fans
  • Water pumps
  • Propane leak detectors
  • Carbon monoxide detectors
  • Smoke detectors
  • 12-volt refrigerators (two-way or three-way)

It is the same type of outlet that is known as a “cigarette lighter”. This type of power converter or battery dependent.

AC (or Alternating Current) is a current that periodically reverses or alternates directions. AC power is commonly used in our houses and it is also the same power supply that is coming from a pedestal in the RV park.

Even though everything (besides computers) in our houses is powered by AC, not many things in your RV use this type of power supply. 12-volt DC power is usually sufficient for many applications, including lights.

For larger things in your RV, you may want to utilize the GREAT POWER of the generator. Solar panels could also assist you in refilling your battery bank while out there on the road.

So how do you interconnect them all? An ALL MIGHTY Automatic Transfer Switch (or Changeover Switch) will help you out with this complicated task.

2-way Transfer Switches change the power output between inverter (with batteries behind it) or shoreline power, to supply your RV with electricity:

You can download here PDF version of this picture for greater detail.

3-way Transfer Switches change the power output between inverter (and battery bank), shoreline power, and a generator to give your RV all the power you need, any time you need it!

Here is the schematic PDF and this is the wiring PDF.

Now, you understand why the electrical system in RV is a multitude of power devices that are there to support you and your lifestyle. Here are some of those devices that any RV must-have:

  1. Battery. A good set of batteries is a must-have in RV if you ever want to get away from shore power.
  2. Inverter. You will need this device to converter 12-volt battery DC power into 120-volt AC power, that some of your appliances probably use (like residential refrigerator).
  3. Converter. If you are serious about camping, you need a device that will charge your batteries. Also, it can convert 120-volt shore power into a 12-volt DC power supply that is used for your lights and few other DC-powered devices that you probably have.

Now, let’s talks about “optional devices” that will really help you with having an exceptionally comfortable RVing experience:

  1. Inverter-Charger. That is in case you would like to save on space and instead of getting two devices (inverter and converter), you can have one that combines both. Higher-end inverter-chargers include transfer switches as well.
  2. Automatic Transfer Switch. This device will assist you in automatically transferring power from your 120-volt shore power, batteries, and a generator. Some models offer a “power-assist” option, where high surges could be directed to another source of power if the main one cannot handle it.
  3. Battery monitor. It is not really an option if you don’t want to damage your batteries!
  4. Generator. Using a generator will allow you to power larger appliances if you have a very limited power service.
  5. Solar panels. Well, there is some space on the roof, right???

Here is how the complete RV wiring looks like:

An this is a PDF file of the schematic diagram and a PDF file of the wiring diagram.

The wiring that runs your RV (and conveniently powers all the electrical gadgets that we love and need) is getting its energy from a huge electrical cord that is connected to a pedestal with outlets in the RV park. This plug is wired to a 120-volt breaker panel that powers your 120-volt devices and a converter charger.

The converter (or converter-charger) is connected to the 12V DC fuse box. This panel contains wires for your fans, lights, water pump, and other 12-volt outlets. There is also a link between battery and converter, and it charges it by converting 120-volt shore power into 12-volt DC.

The power inverter gets connected to the batteries as well, but its only function is to convert 12-volt DC battery power into 120-volt AC. Here is how the inverter is wired to the battery bank:

Feel free to download this PDF file for your reference.

Types of RV wiring services

Many RV parks and campgrounds provide electricity service for RVs and you want to plug it into a receptacle that corresponds to your specific wiring type. The most common RV wiring services are:

  • 20 amp. Smaller campers and trailers.
  • 30-amp. Medium size RVs.
  • 50-amp. Larger size RVs with 2 A/C units.

20-amp RV Service

A 20-amp power receptacle resembles a regular household socket and provides 20-amp power at 120 volts:

It is the same type of outlet that you find in your house:

From 20-amp outlet you will get 2,400-watt service:

20 amps x 120 volts = 2,400 watts

If you are not lucky and they only have 15-amp service, you will get a whopping 1,800 watts of power! In this case, use your electrical devices wisely and one by one.

30-amp RV Service

The majority of small and mid-size RVs have 120-volt 30-amp electrical services. If you have a three-prong plug that looks like this:

…find an outlet on your shore power pedestal that looks like this:

This service will supply you with more power than 20-amp service, but it still is not powerful enough to accommodate surge levels of large appliances (like A/C) or many devices used at the same time. So, how much power do you exactly get?

30-amps x 120-volts = 3,600 watts

This means that surpassing the total 3,600 watt capacity in your RV at any time, will most certainly trip the 30-amp breaker! Watch your wattage use and make sure you don’t use the microwave, coffee maker, hairdryer, space heater, and your TV at EXACTLY the same time!

What happens if only a 20-amp service is available at your campsite? You can acquire this wonderful Camco adaptor (paid link):

And watch your power intake even MORE CAREFULLY…

50-amp RV Service

Many larger RV parks have a 50-amp power outlet at your service! If your plug looks like this (with 4 prongs):

… then you have a 50-amp electrical service and need an outlet that looks like this:

This service includes 12,000 watts of power which can be used to power quite large devices like an air conditioner. How did I get this number when there is only 50-amp of power?

This particular service provides two 120-volt hot wires and if you multiply them by 50, you will get the following number:

(50+50) x 120 volts = 12,000 watts

What if you have 50-amp electrical service and only a 30-amp outlet available? NO problem, dog-bone adaptors like this one sold on Amazon (paid link) can help you out here! Woof!

The only problem in this situation is that you will NOT get your normal 12,000 watts service, but only 3,600 watts that 30-amp power supply offers.

Battery bank

The last, but not least important element of your RV’s electrical system is a battery! It is commonly referred to as a “house battery” and it is typically 12 volts.

Lead-acid batteries are the most popular batteries that RVers use, but lithium-ion batteries are gaining more approval now in the RV world. Lithium-ion batteries outlast traditional lead-acid batteries, they are more durable and their life expectancy is a lot longer.

These batteries are initially more expensive, but when you consider how long they last and how much power they provide, they may be worth giving a shot! Lithium-ion deep cycle 200AH battery (paid link) is a perfect choice for any RVer:

How do batteries get charged? Here are some wiring schematics for you.

Generator and shore power

They can be charged from 120-volt shore power or a generator:

This is a PDF file of the above schematics and another one for wiring (PDF).

Let’s add some solar panels!

You can also add a photovoltaic system (or solar panels) to the setup and you get an ultimate power machine in your RV!

Here is the schematic PFD diagram and wiring PDF diagram.


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