A Guide for Troubleshooting Your RV Electrical System

Because a motorhome or camper is meant to be mobile and moved from place to place relatively often, one common problem an RVer is likely to encounter are issues with their electrical systems. Over time, fixtures can become loose, wire can wear down, and fuses are likely to fail due to movement or an occasional overload to the circuit. In this guide, I’ll explain some of the things I look for when I have a problem with my electrical system and what I do to solve those issues.

Before you troubleshoot or attempt any repair to your RV electrical system, you’ll need to understand that first and foremost, working with electricity can be dangerous and even deadly if you are not familiar with how it works or how to properly repair a problem you may encounter. If you have exhausted your understanding of your electrical system and you have not yet solved the problem or you feel uncomfortable working with your electrical system, then I highly recommend that you consult a professional that can diagnose and repair the problem. To do otherwise may cause further damage to your RV and even physical harm to yourself or others working with you.

Systems you’ll encounter while troubleshooting

The first thing you should understand when working with your RV electrical system is that almost every RV has two electrical systems. One is a 12-volt system where that power is generated through your tow vehicle or motorhome’s engine while driving down the road and any other alternative source such as solar panels or gas, diesel or propane powered generators.

Typically, this system will supply power to lower voltage lights that are used when you don’t access your shore power electrical supply or are using an appliance such as a slow cooker or refrigerator that is designed to work on a 12v electric supply. Smaller campers may utilize this type of system more often than larger RVs and motorhomes, but this type of power supply is very popular and works well for those that want to utilize their engines to produce a power supply and regenerate their battery supply while driving down the road. This type of power supply works especially well for a professional driver of a semi-truck and it allows them to use a slow cooker and keep a small 12v refrigerator working with minimal draw from their battery system while traveling from one place to another.

With any luck, once you have arrived at your destination for the night, your slow cooker has cooked a nice dinner for you and your refrigerator has cooled off well enough that it won’t need to draw more electricity than what is in your battery bank while you are parked overnight.

The other type of electrical system you’re likely to encounter in an RV, is a 110/120-volt system such as you would find in sticks-and-bricks homes or apartments. This system is commonly supplied with electricity by means of accessing your shore power and often a 12v system and a 110v system will work together when your RV is equipped with a converter or inverter that I explained in a previous article about understanding you RV electrical system. 110v systems can also be supplied by using solar power or portable generators that can operate on gasoline, diesel or propane fuels.

I think the two most important things to consider when dealing with your RV electrical system, is whether you can diagnose a problem as to its severity and whether you have the knowledge to repair it without risking injury to yourself or others. For example, one of your 12v wall lamps is not working when you turn it on; this may a fix as simple as a burned-out bulb, blown fuse or a bad switch. However, if you are having a problem with your air conditioning unit and you have checked the power supply as well as the breaker box and it’s still not working, then maybe you should consider consulting a professional electrician or heating and cooling specialist.

For those of you that follow my columns here, I recently shared a guide to troubleshooting your RVs air conditioning system, and in that guide I stressed the importance of understanding electricity and components that can be in appliances like these or refrigerators. As an example, most refrigerators and air conditioners have capacitors that can store as much as 25,000 volts and when not handled properly can cause serious injury or even death.

First, look at the basics

The first thing you should do when something electrical is not working correctly is to consider the basics and understand your RVs circuitry. For instance, the four wall lamps in one of my 5th wheel slide-outs are all connected on one line from the fuse box. One light doesn’t work but the other three light up. What does that tell me?

It tells me that I’m getting power through the circuit and that it’s likely the problem with the faulty lamp is with its bulb or switch. These are both problems that are easily fixed. On the other hand, if all of the lights on the circuit aren’t working then it’s time to work your way back in the circuitry and take a look at the fuses and breakers.

Where are my fuses and breaker boxes?

This can vary by the manufacturer of your RV or whether you have designed the electrical systems to fit your needs. As a rule, most manufacturers will position a 110v breaker box that handles your shore power near a fuse box that regulates your 12v power supply. This wiring configuration is designed so that it makes it easier for the user to stick to the basics and work their way back to the problem. However, I have seen 12v fuse boxes in some RVs located near the house battery bank and not anywhere near the breaker box that handles the distribution of your 110v system so it’s always best to consult your owners-manual when trying to determine the exact location of your fuse boxes.

What are ground fault indicators (GFI) and how do I reset them?

Photo credit: Home Depot

You may have noticed that the electrical outlet near your kitchen or bathroom sinks as well as outlets on the exterior of your RV will sometimes have a red light or two buttons in the center of them.

One button is to test to see if your outlet is working properly and the other is a reset button. Occasionally an outlet may have too much of an electrical draw on it at one time and this acts as an inline circuit breaker that prevents the outlet from overloading and becoming too hot.

However, ground fault indicators are mainly designed to make the user aware that there is a faulty ground and that there is a leakage of current that could cause injury. For example, you’re doing your dishes and you accidentally knock your toaster into the sink. Rather than energize a sink full of water with electricity causing serious injury or even death to you, the ground fault will pop and stop any current from leaving the receptacle.

These ground fault indicators can be reset by depressing the reset button. If they stay in, they are reset, but if they continue to pop back out, then you a larger problem and may need to consult an electrician.

What causes a ground fault indicator to engage?

Water. Usually water is the main cause of a GFI tripping. For instance, one time I spilled a bowl of water on my kitchen counter. I thought I had it all cleaned up but later when I went to use my microwave oven, I discovered that I had no power. Upon looking further, I found a puddle of water behind my microwave and the power cord was laying in this water. Even though the cord to my microwave was well insulated, the GFI tripped because it sensed a loss of voltage in its circuitry which meant the oven wasn’t properly grounded.

Improper shoreline ground. One very common cause of a GFI trip happens when an RVer plugs their unit into the shore power at an angle and the electric connections make contact before the ground terminal. Simply resetting the GFI should solve this problem as well as plugging your RVs shoreline power receptacle into its power supply more level in the future.

Malfunctioning appliance. Since your RV is in motion much of the time, items such as small kitchen appliances and even power tools can have wiring that works loose or becomes frayed over time. Sometimes a new power card to the appliance will solve this issue, but if the problem is within the appliance, then it should probably be replaced.

Older motor driven tools or appliances. This is uncommon, but occasionally an older appliance such as multi-speed blender or circular saw from an earlier age will cause a ground fault indicator to activate. This is caused by the internal motor that has a spinning copper coil that arcs as it contacts other parts of the motor. Since this causes a fluctuation in circuitry and an improper ground, the GFI will trigger and the device will not be supplied with current.

You. This is when you’ll understand the importance of a ground fault indicator. Sometimes you’re the ground in the electrical circuit and this can happen for several reasons. For example, you’re outside and the extension cord you’re holding is in wet grass. Now you’ve become part of the ground circuitry. It’s always better to have a tripped GFI than being electrocuted.

How do I fix fuses in my RV?

First, locate your fuse box and look for the fuse that has failed. With any luck, your box is labeled, and you can quickly locate the fuse that has blown. If this isn’t the case, you’ll need to pull each fuse and visually examine them. Usually a blown fuse in your 12v system will have discolored terminals or a broken copper wire in the part of the fuse where you can see the terminal connection. If this is split, your fuse is broken, and electricity is not flowing through it and it needs to be replaced. However, never replace a 12v fuse with a higher amperage 12v fuse as this can cause an overload in that circuit. Fuses are always marked by color and text and you should always replace a fuse with the same type, voltage and amperage. To do otherwise could cause a fire or personal injury.

Final thoughts on troubleshooting your RV electrical systems

Always remember, when troubleshooting your RV electrical systems, be it your 12v or 110v systems, work your way backwards from the problem. If your socket isn’t working, then look at the power supply to that socket. If your power supply to the socket isn’t working, then look at the breaker or fuse box. If those boxes aren’t working, then you’ll need to examine your main power supplies be it shore power or alternative means.

If you’ve done these tasks I’ve outlined here and you still have no power, consult a professional to guide you through the repair. As always folks, stay safe and thanks for following my columns. I hope to see you out there on the road someday.

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