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It is confusing when you see more than one plug to connect your RV up to the electrical supply. The plug states 30-amps, but the power supply reads 220 volts.

So how do you work out which socket to plug it into? Do you swallow your pride and ask another camper, or is there a way to work out the correct connection?

A 30-amp RV plug will only work on a 110-volt circuit because it only has three prongs, and on a 220volt, a 50-amp circuit has four prongs. While you can use a converter plug to connect a 50-amp circuit to a 30-amp circuit, it is not wise to connect a 30-amp circuit to a 220 volt, 50-amp circuit.

American electrical supplies are all 110 volts as standard. The RV parks offer two connection points, one is 110 volts at 30-amps, and the other is 220 volts at 50-amps. A higher amperage circuit gives the RV owner greater flexibility because the amps which each appliance draws accumulate and very quickly exceed the capability of the circuit, which will cause it to trip.

Having spent a good part of my life traveling in RVs in different parts of the world, I have worked out what works and the easiest way to tell what the combination is in America.



What Voltage Does A 30-amp RV Plug Need?

If the plug and socket in your RV are labeled as 30-amps, it will accept a voltage of 110 volts.

Whereas many other countries use 220 volt/ 240volt systems, the standard voltage in American electrical systems is 110 volts.

You Can Tell The Voltage On The RV By The Design Of The Plug.

The plug on an RV with a 30-amp plug, which delivers 110 volts, has three prongs. As follows:

  1. A single 110-120 volt hot (live) wire.
  2. One neutral wire.
  3. A ground wire.

To deliver 220 volts to the RV, a second live wire is included in the bundle.

Each live wire carries 110 volts which are 180 degrees out of phase with each other. When combined in a 50-amp circuit plug, it results in 220 volts.

The connection on an RV equipped with a 50-amp service delivers two feeds of 110 volts each (220V total) and has four prongs.

  1. A 110-120 volt hot (live) wire (L1).
  2. A second 110-120 volt hot (live) wire (L2).
  3. One neutral wire.
  4. A ground wire.

If your RV camper has a 30-amp 110 volts service, it is important that you be aware of the fact and only use appliances rated for 110 volts.

Appliances Which Need A 220 Volt, 50-amp Circuit

In most instances, a 110 volt, the 30-amp circuit is sufficient for an RV; however, certain appliances have higher draw requirements, and if you want to use them in your RV, you will need to modify the electrical installation.

The following table lists the typical appliances in an RV and the estimated power (amps) requirement.

After seeing the list, you may be asking what all of the fuss is about as no appliance in this list draws more than 21 amps, and therefore surely a 30-amp circuit would be sufficient.

The problem is that the amps that are drawn accumulate across all of the devices; therefore, using this table, if the following devices are used simultaneously, the amps drawn would exceed the system limits, and the breakers will trip.

  1. Kettle: 12
  2. Lights: 1
  3. Computer: 3
  4. Air conditioner: 34 (18+16)

If the above appliances are on a single circuit in the RV, they will draw 50-amps which would trip a 30-amp circuit.

Can A 30-amp RV Be Upgraded To A 220 Volt Circuit?

If you have some high draw appliances (such as an air conditioner) that you want to use in the RV, it is possible to convert the 110-volt circuit to 220 volts.

There are three possible methods you could consider using.

Use A “Step Up” Transformer

Purchase a "step up" transformer to convert the current without going through the extensive work needed to convert the system.

The problem with a step transformer is that it is impossible to create or destroy energy. It is reflected in the formula Power= Volts* Amps.

If the voltage increases, the amps will decrease by a proportionate amount; therefore, if the RV has a 110V, 30-amp power supply, a step-up transformer will produce a 220volt, 15 amp supply.

It is not a problem for low amp devices and using the list of items in the table above, and only the air conditioner draws more than 30-amps at start up. If you use the step-up transformer to power individual appliances, it will be suitable. However, if you use it for more than one appliance and the total amperage exceeds 15 amps, it will trip.

Which needs a 220v power supply (such as European TV); however, it is not suitable for high-amp devices like air conditioners.

Convert The RV To 220 Volt, 50-amp Circuits

A viable option is to convert the RV electrical circuit to a 220 volt, 50-amp supply.

As RV campsites already offer the option of 110 volts, 30-amp, and 220 volts, 50-amp power supply, there is already sufficient power at the source to provide the necessary current.

The new circuit will be required to carry a higher current and, therefore, will need thicker wiring (lower gauge) to carry the increased number of amperes. If it is not increased, the appliances which draw 220 Volt, 50-amp current will cause the wire to heat up, and if there is not a suitably sized circuit breaker in place, a fire may start.

Although not difficult, the conversion does require new circuit breakers,  replacement wiring, and different plugs on some of the circuits in the RV.

If you do not have electrical installation experience, it is recommended that you appoint a specialist RV electrical technician to do the work.

Use An Extension Cord

Another option is to attach a dedicated electrical extension cord directly from the RV park's 50-amp plug to the appliance in question.

Things to consider before going this route:

  1. The length of the connection
  2. How the device is wired to the RV

The Length Of The Connection

If the RV is parked a long way from the park's power supply, you need to ensure that the extension cord has sufficiently seized gauge wires to cope with the current. It probably isn't an issue for one extension cord; however, if you are "daisy-chaining" several cables together to achieve enough length, it probably is a problem.

How Is The Device Wired Into The RV?

If the device is wired into the RV and the connections aren't easily accessible, this solution will be a problem.