RV power cords and adapters are pretty straightforward. Just plug them in and you're all set, right? Well, maybe. If you have the right cord and the right adapter and plug it into the right source, it really is that simple. However, if any of those are NOT right you could and probably will have problems, ranging from poor performance to fire!
Most RVs come with an attached power cord that is appropriate for the power needs of the unit. Most RVs have either a 30 amp or 50 amp electrical system. 30 amp systems have a 3-prong plug; 50 amp systems have a 4-prong plug. It is virtually impossible to plug these into the wrong receptacle without using some kind of adapter. I have seen some truck campers and older trailers that have a separate power cord and it is easy to use the wrong one here. The unit is equipped with what is called a ''motor base''. This is essentially a recessed male electrical plug into which the female end of an ordinary extension cord can be plugged in to supply modest power needs of these small RVs. If anyone has added electrical components, such as heaters, A/C, or even TVs that significantly increase the power demand these connections might not be adequate. Likewise if any RV has significant electrical additions it could exceed the capacity of the original power cord. Most RVs use a 3-prong, 30-amp power cord but some larger units have 4-prong, 50-amp power cord. Regardless of which one you have, it is imperative that you do not exceed the rated capacity! Monitor use of appliances with high power draws, such as air conditioners, electric dryers, and electric heaters and make sure you don't try to run too many at the same time. Even some hand-held devices, like hair dryers, consume significant amounts of electricity.
There are many different types of adapters available to give you more options. However, just because you CAN install an adapter it doesn't mean you SHOULD use it! You can get adapters that let you plug your 30 or 50 amp RV cords into an ordinary 15 amp household receptacle if you don't have a 30 amp RV receptacle at home. That is OK if you don't try to run any high-amperage appliances (like air conditioners and electric heaters). It will usually run your lights and power the fan on your furnace just fine and let the converter keep the house batteries charged. A lot of RVers use a 15 amp adapter when running electric heaters in their RVs in the winter and that is BAD NEWS! Very often the adapters will overheat, even to the point that they melt and could cause a fire. Using an adapter to plug a 30-amp cord into a 50-amp receptacle shouldn't be a problem since the power available exceeds the demand from the 30-amp rated vehicle but you should still keep an eye on power usage so you don't exceed the rated capacity of your RV power cord or the adapter. The other way around (using and adapter to plug a 50 amp cord in to a 30 amp circuit)could overload the circuit.
Another common problem of inadequate connections comes from using adapters and ordinary extension cords with standard 30-amp or 50-amp RV power cords. Adapters are available that allow you to connect both 30 amp (3-prong) and 50 amp (4 prong) RV cords to regular 15 amp female outlets and ordinary extension cords. These allow you to use low demand features like the 12-volt lighting but should NOT be used if you are using higher demand appliances like heaters or air conditioners. NEVER use less than a 12-3 extension cord. 12-3 means it uses three 12 gauge conductors. Smaller gauge cords will be likely to overheat and short out, possibly caused a fire. Smaller gauge cords are less expensive but will cost you more in the long run because they can cause damage to electrical motors and appliances as well as increasing the risk of a catastrophic failure of the cord itself. There are small, self-contained adapters that connect RV plugs directly to 15 amp female receptacles. These will usually work fine for just running the lights, but if you use them to run heater or any other high amperage appliances they will over heat. I have seen them melt both the female receptacle on the extension cord and the plug on the RV cord to where they could not be separated. Larger, more expensive adapters consist of separate plugs -- a receptacle for the RV plug on one end and an ordinary 3-prong 15 amp plug on the other, connected by a heavy duty cable. These adapters will be less prone to over heating but using high demand appliances in the RV could still result in damaging the connections, overloading the 15 amp circuit, or over heating the extension cord. Also be sure to fully extend extension cords when using them. If you leave part of them rolled up they can overheat often to the point of melting the rubber outer layer and perhaps causing a fire!
I recently had an RV shop tell me they get lots of customers asking why their adapters burned up and they said virtually all of them had been running electric heaters in their RVs. The load of the heater is not enough to trip the circuit breaker but continuous operation builds up heat in the adapter until they melt and fail. Owners do that, of course, to prevent freezing during cold winter months, and it seems to work OK -- until the adapters burn up! Much better to properly winterize the water systems on the unit and remove all contents that might freeze. And you won't be wasting money running the heater or replacing burned up adapters and power cords.
If your RV is too far from the receptacle for the built in power cord you can purchase both 30-amp and 50-amp extension cords. They are not cheap, but they will function properly and safely. And they can be used for very long reaches. I recently read that cables appropriately sized for 50-amp RV cords can be used for up to 60 miles! 30-amp version are rated up to 20 miles. No one is going to run extension cords any where near that far, but is nice to know they will work properly for our RV if we need to run an extra hundred feet or so. The general rule for ordinary extension cords should not exceed 100 feet! If you must use an ordinary 3-12 extension cord to reach or RV avoid using any high-power appliances. About the only safe thing to run is lights; A/Cs, electric heaters, and water heaters will exceed the safe capacity of the 3-12 extension cord and/or adapter.
Proper handling of power cords is essential to ensuring good connections and long life. The most common abuse comes from mishandling the connectors You should always plug and unplug cords by getting a firm grim on the connector. Pulling or pushing on the cords tends to break the cord right where it enters the connector, which can cause failure, might shock or even electrocute you, and could start a fire! Similarly, bending cords close to the connectors weakens the wires and can cause problems. Of course, you won't have good results if the plug isn't inserted firmly into the receptacle either. Another fairly common problem is leaving excess cord rolled up when in used. This can result in heat buildup that can melt the insulation, which results in failure and possible fire. Cords can be damaged by being run over or dragged over sharp objects or from contact with rough vibrating surfaces. Inspect all your electrical cords frequently and replace or repair any that have been damaged. Small nicks in exterior insulation can sometimes be temporarily repaired using electrical tape, but cords with deeper cuts should be replaced or the damaged section cut out and proper repairs made to reconnect the remaining good parts. Connectors can be damaged if the cord is yanked or pulled at an angle and sometimes burn out due to poor wire connections inside. Good repairs should include properly soldered connections and safe repair or replacement of insulation. If you are not absolutely sure you know how to make proper, safe repairs, replace the cord or have it repaired by a professional. Damaged connectors are fairly easy to replace if you have basic tools and are reasonable skilled.
Using the right power cord, adapters, and extension cords (if needed) can deliver safe and adequate power to your RV. Proper connections will relieve you from having to worry about damaging appliances and equipment in your RV, melting adapters and connectors, or over heating the extension cord.
Power up safely!