Troubleshooting and Repairing RV Electrical Problems for the Beginner
Electrical Problems in RVs: For the Novice
Electrical problems in an RV or camper are very common, and often RV owners don’t know where to start when they deal with them.
This article provides some basic information for the RV owner to help diagnose and repair electrical problems efficiently and safely. I'd like you to:
- Understand your RV electrical system in general.
- Learn how to do some very basic troubleshooting on your RV.
First: Know the Difference Between a Major and a Minor Electrical Problem
If you own or rent an RV, you will want to know enough to at least make a walk-around inspection before you go on the road, especially of the electrical system. Even a novice can learn how to inspect for problems, and determine if the problem is major or minor.
A major problem, for example, may be present when a refrigerator stops working, and you wonder if you should look into the wiring and propane-management circuitry on the back of the fridge or not. For the electrical novice, the answer is no; stay away from such repairs yourself. They are too dangerous, especially when they involve AC power or propane. You should always contact a qualified service tech for resolving such problems.
But a minor problem, one you could address on your own, could be something as simple as re-setting a breaker or GFI that has "kicked out," replacing a blown fuse that is easily accessible, taking an educated guess as to what caused the breaker or fuse to shut off, or checking the water in your battery.
So how do you tell? Before you start with any hands-on troubleshooting, keep in mind that safety comes first.
Electricity Can Kill!
Please remember this when using the information below!
Before you start opening panels and messing around with electrical systems, in an RV or camper or at home, observe these warnings.
WARNING 1: If you do not know what you are doing, do not touch anything, and call your RV manufacturer, or RV Roadside Assistance company, or if at home, your local certified electrician. Remember, again, ELECTRICITY CAN KILL!
WARNING 2: If replacing a blown fuse or resetting a kicked breaker doesn’t fix the problem, you should seriously consider backing off and calling your RV manufacturer's Service Center for advice before doing anything else.
Now—with these warnings in mind—here are some minor problems that you may be able to fix, and some diagnostics that you can run yourself.
Troubleshooting Your RV's Electrical Problems
Every problem is different, but before or after you read the discussion just below of the basics of your system, check the four sections further below on troubleshooting common problems:
- Fuses and breakers
- The 12-volt system
- The power source
- Appliance current draws
Plus I include a section on terms and abbreviations that you may run across while doing your electrical investigation.
Some Basic Electrical Information for the RV Owner
A modern RV contains a lot of built-in electrical devices. And along with these devices comes complicated electrical control and protection circuitry designed to protect the RV and its occupants.
Starting with the absolute basics, your RV's appliances can be powered in three different ways. Appliances may use any of these three power sources, individually or in combination.
▪The AC (alternating current) electrical system (generally 115 volts), which runs the air conditioner and some other devices.
▪ The DC (direct current) system (12 volts), which runs the lights, switches, slides, and thermostats.
▪ In addition, refrigerators and some appliances run on propane fuel.
AC power comes into the RV from your generator, or from the campground or other outlet you plug it into: a 20-amp, 30-amp, or 50-amp supply. The AC power control panel distributes this power to the appliances and outlets that use AC power, for example the air conditioner. The campground supplies AC power on two different wires: a 240-volt supply is split into two "legs" of 115 volts or so.
Your DC power comes from a battery or batteries (like in the picture above). Whenever the power stored in the batteries gets low, the converter charges it up. The converter uses the higher-voltage AC power that comes in from the campground or generator through the 115-volt AC breaker panel and converts it to 12-volt DC.
The converter that charges your 12-volt batteries is often called an "inverter." "Inverter" is actually the name for another device most RVs have that changes 12-volt DC power to 115-volt AC for use in televisions and such.
The 12-volt output of your converter likely goes through two 30-amp fuses that feed your 12-volt fuse panel. The 12-volt DC power goes to the lights, switches, and slides, and to the controls of many appliances including the heater/air conditioner and refrigerator.
Both electrical systems can develop weakness in many places, especially when being hauled around on trips. Any RV or towed vehicle vibrates in transit. And these vibrations will, at times, shake electrical connections loose, in addition to the wear and tear that wires and appliances go through in normal use. If a wire has its insulation rubbed off, or something inside an appliance shakes loose or burns out, then current can stop flowing in your 12-volt or 115-volt system. Or it can flow into a place where it is not supposed to flow, causing a “short,” and this excessive flow of current can burn out wires and appliances, or in the worst case cause a fire or injury.
Because of these risks, the RV will have breakers or fuses to shut off power if anything goes wrong:
- a set of AC fuses or breakers to interrupt the 115-volt AC power coming from outside the RV if anything goes wrong in the 115-volt system.
- a set of DC fuses or breakers to interrupt the DC power if anything goes wrong in the 12-volt system,
- and also, in many 110-volt receptacles, mini-breakers called GFIs or GFCBs (Ground Fault Indicators or Ground Fault Circuit Breakers), which shut off power to appliances if a wire or circuit is creating a short.
1. Troubleshooting Fuses and Breakers
Troubleshooting often begins, and may well end, with resetting a breaker, replacing a fuse, or resetting a Ground Fault Indicator, and then seeing what happens. Older RVs tend to have fuses; newer ones, breakers.
The fuses and breakers were placed in the system for two major reasons:
- To protect the RV and you the owner from harm if an appliance or other electrical device or an electrical line fails and draws too much current.
- To protect your RV and its electrical appliances and other devices if you plug your RV into an electrical service that is not regulated properly and you get electrical voltages that are too low or too high for your RV and its equipment.
So a breaker or fuse going off is often a sign that something else is wrong: a symptom, not a cause of your problem. The problem may be easy to fix or it may not be. Many appliances have sensors on their mechanical parts that will kick a breaker or blow a fuse rather than allow the appliance to continue running in an unsafe mode.
Note that breakers can go bad themselves; if they trip too many times, they can suffer mechanical stress and lose their ability to stay closed at the current they were designed for.
Ground Fault Indicators
A GFI or Ground Fault Indicator (also called GFCB) is a receptacle with a RESET button on it. It is designed, like a regular circuit breaker, to "throw" itself off when the current through it exceeds its designed current limit. Additionally, a GFI will throw itself if even a small amount of current is detected between the "hot" lead and the ground lead of the circuit breaker. These specialty circuit breakers are required in areas such as bathrooms, kitchens, and garages, places where the user of an appliance could possibly be physically touching ground through plumbing, metal, or flooring and using an appliance that is not insulated properly. They are life-savers.
If you find that several AC appliances at once stop working, or if AC appliances quit working but the air conditioner keeps going, suspect a Ground Fault Indicator. If the GFI detects a problem, the GFI-equipped receptacle will shut itself off, often along with several other "slave" receptacles. Push the RESET button and see if that fixes the problem; if not, disconnect all appliances and plug them back in one by one. The problem may be a single faulty appliance or something else entirely. It's possible (though not the most likely thing) that the GFI receptacle itself is bad and needs replacing.
Don't Upgrade Your Fuses
Don’t try to fix your problems by replacing your fuse or breaker with a higher-rated one. Your camper or RV was designed by professionals with your safety in mind, as well as your convenience. Each electrical device was installed on an electrical line that could safely handle the load.
Putting in a higher-rated fuse or breaker does not fix any problems. If you have a blown fuse, replace it with a fuse of the same rating, NEVER a higher-rated fuse. Because:
- You could cause an electrical fire and destroy your RV.
- You could permanently damage the equipment that is supplied by that fuse.
Always remember, the fuse was designed for a normal operational load. And if it blew, something has changed.
With these warnings in mind, below is a table of fuse colors and what ratings they indicate, in case you go shopping for replacement fuses.
Standard automotive fuses are color-coded according to their current rating; below is a short list for your reference.
Amperage rating (amps)
2. Troubleshooting 12-Volt System Problems
A bad connection in the 12-volt system can cause failures of various appliances, including slides and lights which run on 12-volt power. A 12-volt problem can cause failure of other appliances and systems if they have 12-volt power to their controls. The refrigerator and air conditioner, even running in propane-fueled mode or on AC power, require DC voltage for their logic circuits, and so may fail to operate when there is a DC system problem. Problems in the DC system can also cause lights or appliances to go on and off.
You can so some simple investigation of the 12-volt system yourself, for example:
- Check whether the fuse or breaker is tripped or not.
- Check whether the fuse is loose.
- Check whether the connections to the fuse or breaker box are loose.
- Check whether the connections to the DC batteries are loose (see initial photo).
- Check whether the batteries have enough water. This is the most common easy-to-fix problem. When your battery is overworked or overheated the water tends to evaporate. Add distilled water only.
- Check whether the batteries are charged enough. A multimeter (see below) should show the voltage between the battery terminals between 13.4 and 14.5 volts DC; if not, the battery may be worn out and need replacement, or it may be low on water, or the converter may not be giving it any power.
- Check whether the connections to the converter are loose.
- Check the fuse on the converter. The converter itself has a fuse or two, often on the front.
If you can find nothing wrong here, you may have a bad converter that needs to be replaced; this is a job for the service center, though the adventurous can read a little more in this other article about troubleshooting converters.
Another article of mine has more information about troubleshooting and maintaining your RV's batteries.
Using a Multimeter
A multimeter can measure potential (DC volts, AC volts), electric current (amps), and resistance (ohms).
This device is very useful in the hands of a trained individual, but the novice should not attempt to use all of its functions until they understand what they are trying to measure as well as any dangers involved in making the measurements.
When my old multimeter died, I selected this one for its functions, ruggedness and ease of use.
3. Troubleshooting Problems Coming From the Outside Power Supply
The power supply that your parked RV is plugged into can cause problems if it is supplying too much or too little power, fluctuates, is not grounded correctly, or its connector is corroded. Too much current can cause appliances or lights to fail or blow out, and even melt wires or plugs; too little (in an overpopulated campground with an overloaded supply, for example) can cause lamps to dim. Your campground management should be providing safe power at the level they advertise, whether 30 amps or 50 amps; that is their responsibility. You may ask management to investigate, or check with your campground neighbors to see what they are experiencing.
If half your appliances along with your air conditioner are out, one possibility is that half the AC supply from the campground is missing (another possibility is a GFI going off; see part 1 above).
Your on-board or portable generator can also be the cause of problems; it may stop running if your vehicle's gas tank is less than 1/4 full.
Most RVs have a master switch for disconnecting your RV's power during storage. It is a small switch, often near the door on the inside. It will need to be on for you to get power.
Surge Protector, Yes or No?
Everyone in campgrounds seems to be purchasing surge protectors these days. I don't have one. If you buy one, make sure you are purchasing a GOOD one.
Your RV already has surge protection devices: your main AC breaker plus the individual appliance and equipment breakers in your main breaker panel. Like surge protectors, they kick out if the input voltage goes too high.
The only real difference between breakers and a commercial "surge protection" device is that standard breakers are slow to react to voltage changes. A good surge protector should react faster than a breaker to voltage increases and kick out if the voltage exceeds the safe limit of your electrical equipment. Because low input voltages can also harm electrical devices or make them run erratically, most surge protectors will also turn the power off when the voltage is too low.
Now the problem with surge protection devices is that there are no real requirements or specifications for their design. You could purchase one that does not react fast enough to protect your RV equipment. Many of my fellow campers who had surge protectors experienced damage that "fried" their breakers without the surge protector helping at all.
Anyone who buys one of these devices should make sure they get one that has a relatively fast response time, though it's difficult for a camper to tell how fast one surge protector is relative to others.
4. Troubleshooting AC Current Draws
Once again, I recommend that you NOT mess with your RV's 115-volt power system unless you really know what you are doing.
But if your AC breakers or fuses are going off, you can certainly investigate whether your appliances, singly or in combination, are drawing more AC power than you want them to.
Remember that problems with your AC appliances may not come from your 115-volt system at all but from your 12-volt system, because the controls for your fridge and your air conditioner and heater—and other switches here and there—are likely 12-volt.
How Much Current Do Your Appliances Draw?
It's good to know which of your appliances use a lot of current, even when they are working properly. That way you can decide when and where to use your appliances so that the flow of electricity stays within the bounds your system can handle.
The table below lists the approximate MAXIMUM current drawn by common appliances in your RV. Most appliances draw a lot of current during a short period of intense use and less current at other times. These current figures are not exact and vary by manufacturer and model.
Air conditioner (rated 13,500 to 15,000 Btu)
Peak use when starting up
Normal rate after it gets going
Coffee pot (maximum use, while perking coffee)
Once the coffee is brewed, the hot plate under the pot uses much less power, especially if you turn its temperature down.
Less powerful hair dryers might be better for RV use.
Crock pots are useful for cooking in RVs.
Electric frying pan
Hand vacuum (small)
1.5 to 5
Depending on the size, the manufacturer, and the technology.
Water heater (in 120-volt AC mode)
Estimating Maximum Current
If you are unsure what current an appliance draws, use this simple method to calculate the maximum current it will draw when working.
- Look for the appliance's power rating in watts. You may find it on a label on the appliance, or in the owner's manual, or you can contact the manufacturer or look online.
- Divide the number of watts by 120 (the AC voltage), and the result, in amps, is the maximum rating of the appliance for current.
Or you can measure the current an appliance uses with the simple tool below.
If you suspect an appliance of drawing too much current, use this handy meter and monitor what it actually uses. This is a valuable tool for your toolbox.
Useful Electrical Terms, Abbreviations, and Data
Here is a list of electrical terms and abbreviations, along with a list of color codes for resistors. This information should help the novice be more comfortable with what they are doing when an electrical problem does occur.
Alternating current reverses polarity and flows alternately in both directions in a circuit.
The voltage in your home is AC voltage, in the US typically 115V AC.
The measure of electrical current
An electrical component that stores electrical energy, with a specific storage capacity
A capacitor often has a polarity and must be installed properly. The polarity is generally indicated by a stripe at one end of the part.
A device that opens up or "throws" itself to break a circuit when the current through it exceeds its designed limit. Unlike a fuse, a circuit breaker can be reset when it throws.
Direct current flows constantly in one direction, commonly from a positive lead to a negative lead.
An electrical component that allows current flow in one direction and impedes current flow in the opposite direction.
Current flows from the cathode to the anode. The cathode end is usually marked by a stripe.
A device that is designed to destroy itself or "blow" when the current that passes through it exceeds its designed current limit.
A safety device used to protect electrical devices under adverse conditions. When replacing a fuse, always use one with the same current and voltage rating.
Ground Fault Circuit Breaker
Like a regular circuit breaker, the GFCB "throws" itself off when the current through it exceeds its designed current limit.
Ground Fault Indicator
Same as above
The measure of resistance to current flow.
The resistance can be calculated using the formula: R=V/I, or resistance equals voltage divided by current.
The measure of electrical power.
DC power can be calculated using the formula: W=V x I.
The size of a wire chosen in designing electrical circuits, which determines the current it can handle with minimal resistance.
Standard wire sizes or gauges go from 0 to larger numbers. The larger the gauge number, the smaller the wire size.
One-Letter Electrical Abbreviations
F (upper case)
Farad, the measure of the value of a capacitor. For example, 1 uF means 1 micro-farad.
l (upper case)
Electrical current, measured in amperes. Current can be calculated using the formula I = V/R, that is, current equals voltage divided by resistance.
K (upper case)
One thousand. Example: 1 KW means one kilowatt, one thousand watts.
m (lower case)
One one-thousandth, 0.001. Example: 1 mW means one milliwatt, a thousandth of a watt.
M (upper case)
One million. Example: 1 MW means one megawatt, a million watts.
n (lower case)
One billionth, 0.000000001. Example: 1 nF means one nanofarad, a billionth of a farad.
p (lower case)
One trillionth, 0.000000000001. Example: 1 pF means one picofarad, a trillionth of a farad.
u (lower case)
One millionth, 0.000001. For example: 1 uF means one micro-farad, a millionth of a farad.
V (upper case)
Volt, the measure of electrical potential. Voltage can be calculated using the formula: V = I x R.
W (upper case)
Watt, the measure of electrical power.
Resistor Values and Colors
Gold (as the fourth band)
1% tolerance on the value
Silver (as the fourth band)
5% tolerance on the value
No color (as the fourth band)
10% tolerance on the value
Good Luck Now
The hundreds of comments below have explored just about everything that can go wrong with an RV's electrical system. Add your own questions and comments. But please, again, do not mess with any wiring unless you are sure of what you are doing. Electricity can kill.
Questions & Answers
My 110-volt system is fine. I have brand spanking new 12 volt batteries, terminals clean, all 12 volt fuses fine, all 12-volt cabin lights are fine, but the wall monitor. The tank indicators and pump switch are inoperatv. What do I do?
Your Monitor panel operates on 12-VDC from your COACH batteries, so this one is a little strange. You didn't say what model RV you have, so I will assume it is a motorhome and that you also have a water pump switch in your service center and near the sink, all wired so that any one of them will operate the water pump. SO, do your other switches operate the pump??? Some RV's will have two 12-VDC fuse panels in them; one near the dash and one in the rear somewhere, so check if you have this condition and a bad fuse in the second one.
But, logic says that you do not have 12-VDC to this Wall Monitor panel which you can check with a multimeter.Helpful 1
After my recent furnace board replacement, I have discovered that the a/c unit will only work on high fan setting, it has stopped working on Auto or low speed. I can hear it start up but the fan on the a/c unit won't blow. Any thoughts on that or you think those two problems could be related somehow?
From your symptoms, I would think the most likely cause of your fan speed problem is one of two things;
1- When the furnace board was replaced it was connected improperly. or
2- The new furnace board is thw wrong model number or actually a bad one.
Check these options out and contact the AC manufacturer's customer service number to confirm the board is the right one.
something is draining the chassis batteries on my class c.....removing all of the fuses from the panel does not alleviate the issue....any help??
You have not provided very much information here, but here is something you can check.
Your Class-C has a couple of CUT-OFF switches. One for the Chassis circuits and one for the Coach circuits. They are there to allow you to disconnect the Chassis circuits when you are camping and thus not drain the battery with your engine and dash accessories over that timeframe.
Also, your; power steps, power awning and exterior door light operate on your Chassis battery and can, over time, drain them. So, if you should make sure to start your engine for 20-30 minutes each week to recharge your engine battery. Some motorhome manufacturers even install a small solar trickle charger on the roof to keep the engine battery charged.
On my Class C travel van, there are two small LED lights mounted above the van doors to illuminate entry. They both stay on all the time and don’t power off when the doors shut as designed to do. How do I troubleshoot this?
On every RV I have seen, the over-the-door external light was controlled by a manually operated switch mounted on the wall just inside the door, and not by the door itself. Typically there is a magnetic switch on the door that controls your power step and a light under the step, if you have one, but this is a separate light from the over-the-door light, which people usually want to keep ON while they are outside. This light stays on as long as your power step is extended.Helpful 1
My RV battery, converter, AC control box, thermostat, and wires are all new. I ran a new hot and negative from an empty spot on the fuse board. I’m getting 13.5 plus on my battery, and about 13.5 on the control box. But on the control box, all four ins plus the freeze sensor has 13.5 even when the t-stat is switched off. Also, the furnace isn't working. Do you have any thoughts?
Yes, the furnace is managed by the same control panel as the AC. Again, contact the AC manufacturer's customer service people for help, but at the same time, it really seems like a temperature control panel problem, or there is an outside chance that it is a ground problem, so look for lose or broken ground wiring.