Know Your 120-Volt Electrical System

Although the electrical power used in your RV is similar to that used in your home, there are several unique properties to the 120-volt power that all RVer’s need to know.

This instructional class will walk you through, step-by-step, the key factors of your RV electrical system.

In your home, it’s simple… you turn on the coffee pot in the morning, check emails on the computer, and grab some cold milk from the refrigerator all without thinking about how the electricity makes everything work. It just comes from the pole outside, magically.

In your RV, it’s a little more complex than that! In this 120-Volt Electrical System class, you’ll see how electricity is supplied by the campground source or an RV specific generator to the rig, with the help of a distribution center.

Testing the campground source for proper voltage and polarity is important prior to hooking up your shoreline power. You’ll learn how to use a digital monitor or the less expensive analog version that also requires using a GFCI tester to check for proper wiring. Also, you’ll learn the difference in power requirements between the various power cords used in RVs.

A typical campground electrical stand, which is commonly referred to as shoreline power, will have a 15-amp plug-in with a GFCI outlet, 30-amp three-prong plug, and some will have a 50-amp 4-prong outlet that supplies two legs of 120-volt power for larger rigs. These are all controlled with a circuit breaker switch on the pedestal.

The distribution center is the heart of the 120-volt power source, and you’ll get an in-depth look at how the power comes into the center and is routed to each of the appliances and outlets through circuit breakers. Then we’ll cover how that power is used to charge the batteries through the converter which supplies the 12-volt DC system.

And finally, you’ll hear a discussion on energy management when only 30-amp power is available and troubleshooting basics – including safety tips, surge protection devices, and how to check individual amp draw of appliances and accessories.

In addition to the detailed video instruction you’ll receive, this online class provides you with some downloadable resources and helpful information to print and keep, including: A detailed Class Guide you can follow and use as a reminder for the key points of the class instruction; and a few resource documents that will help you get the most out of your 120-Volt electrical system.

Class Materials:

Session 1: Campground Power Overview

RV Campgrounds receive electrical power from the main grid by either the city municipality or a rural electric company/cooperative. Underground runs typically supply the power to the individual camping sites and up to the electrical post and a covered electrical connection. Most smaller campgrounds charge a flat fee for electrical usage, however more and more campgrounds are adding electrical meters to determine the usage and charge accordingly.

Session 2: Units of Measure

A basic understanding of the different units of measure such as amps, watts, and volts are discussed and their role in the 120-volt AC electrical system. An understanding of these units of measure is important in knowing the limitations your rig might have when it comes to running appliances.

Session 3: What components Run on AC

Not all appliances in your RV operate on 120-Volt power and some even require both 12-Volt and 120-Volt power such as the refrigerator! This section covers the different appliances and their power requirements as well as some that run only on 120-volt power supplied by the 12-Volt batteries through an inverter. These items include small appliances such as the TV but can also be larger items such as the refrigerator through a bigger inverter and larger “bank” of batteries.

Session 4: Different Campground Power

Using a multimeter, we show what voltage is available at the 15, 30, and 50 amp outlets to better understand the system. The 50 amp outlet actually has two 120-volt “legs” going to the distribution center, placing the probes across the hot connectors shows 240 Volts available while going from one hot to the neutral shows 120-volts at each side.

Session 5: Checking the Campground Source

Before plugging your RV into any electrical provider you should verify the source is wired properly and that you have a safe voltage. This session shows a variety of tools you can use to check individual outlets starting with an inexpensive analog meter, a digital monitor, a multimeter, and finally a top of the line surge protector which also has a digital display showing all the information needed to complete these tests.

Session 6: Distribution Center

The distribution center in an RV is similar to the breaker panel in your home as power from the outside source whether it’s campground or generator comes into the panel to a main terminal strip commonly called a “bus bar”. Individual appliances and outlets are connected to this bar through a circuit breaker in the panel as well as the converter which converts 120-volt power to 12-volt to charge the house batteries.

Session 7: Campground Source vs. Generator Power

120-volt power can be supplied by the campground source through the shoreline cord or by an on-board generator. Some models have an automatic transfer switch (ATS) which sense where the power is coming from and automatically switch the source, others need to have the shoreline cord manually connected to a “J” box or outlet coming off the generator.

Session 8: Checking Amp Draw

It’s important to know how much “power” or amps your rig is drawing from the campground source when connected to 30 amp and even more important on a 15 amp source. Then factor in the coffee pot, hair dryer and other accessories and you can easily overload a circuit. This segment shows how to use a cool tool to show what type of draw you will get from plug in accessories to help manage your power draw.

Session 9: Using a MultiMeter

A multimeter is a versatile tool that will allow you to check 12-volt DC power at the house batteries and charging capacity from the converter. On the 120-Volt AC Volt setting it will show proper voltage to outlets, from the campground source, and to appliances. The Ohm setting will show resistance values for testing the refrigerator thermistor and other electrical components. Using either the Ohm setting or continuity setting will provide testing of wiring for breaks or what is called “open” circuits.

Session 10: Energy Management Systems

Most homeowners do not need to worry about shutting off lights, appliances, or heating and AC units when they turn on the microwave to avoid overloading the electrical system. In an RV we need to be aware of the power requirements of appliances and either shut them off manually or use an energy management system that will turn certain energy “hogs” off automatically.

Session 11: Electrical Safety – Hot Skin

RV Manufacturers conform to strict safety regulations mandated and inspected by National Electric Codes and RVIA. There are however some precautions RV owners should take and safety issue to be aware of. Electrical shorts, or improper wiring at the campground or in the rig can cause severe shock if it comes into contact with a ground as well as a slight electrical “current” or tingle known as “hot skin” that is covered in this section.

Session 12: Surge Protectors

Even if you initially check the campground source for proper wiring and voltage, it’s a good idea to have a constant electrical monitoring system like a surge protector. The source may be ok at the time of hookup, but as more rigs connect to the services and the hot weather in the afternoon increase the usage from the units in the campground, it’s not uncommon for older campgrounds to drop voltage as well as an occasional spike at times.

Session 13: Electrical System Diagnosis

It’s important to understand how the electrical system works in your rig as well as how it is supplied to the various appliance to perform proper troubleshooting and diagnosis. Electrical diagnostics can be not only frustrating without the proper tools and procedures, but can be dangerous as well! This session shows you the proper tools and what they will tell you as well as a planned approach for the proper steps in a safe electrical system diagnosis and troubleshooting.

Session 14: Class Summary

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