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It's so confusing to understand the varying electrical services offered by most RV parks. Sometimes the two different plug points are not always clearly marked.

As RVs become more luxurious and better equipped, the electrical power requirements increase, and the need to have higher ampere circuits becomes essential. You need to understand what electrical service your RV requires and how you connect this to the RV pars supply.

A 50 Amp Service is 220 volts, and it is quite simple to tell whether it is a 110 volt or a 220-volt service by the design of the electrical connector (plug). A 110-volt RV service will have a three-prong plug, while a 220-volt service will have a four-prong plug for each of the 110-volt supplies.

North American power supplies are rated at 110 volts. If a 220-volt power supply is required, two power supplies and a common neutral connection must be incorporated into the same plug.

Having towed a camper van in many different countries across varying continents and having received help from so many other people, I would like to pay the favor forward and share some of the tips I have learned.



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

The plug on an RV with a 30 amp or lower service has three prongs. There is

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

The plug-on RV with a 50 amp service 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.

RV campervans with a 30 amp service will generally only have lower amp/watt appliances.

RV campers equipped with a 30 amp power source will experience problems if too many electrical hungry current consumers are connected and switched on simultaneously.

Why Do RVs Have Different RV Electrical Services?

The amps that an RVs electrical system is rated for determining the amount of electrical current it can manage.

The amps which the electrical consumers in the RV use are accumulative. It means that the amps each accessory use add up, and if the total exceeds the value of the circuit breaker, it will trip.

There is another factor in that some appliances need a "surge" of amps when they first start, after which a lower amp's value is used for normal running. Examples of devices that require a surge at start-up are refrigerators and air-conditioners.

If you run an RV with a thirty amp electrical system and constantly battle with tripping circuits, you may need to consider converting it to a 50 amp system.

The typical amps required by common electrical consumers in an RV are shown below.

As you can see, if every appliance is switched on simultaneously, there would be a power requirement of

  1. Normal Amps                 -        115 Amps
  2. Surge Amps                -          43 Amps
  3. Total Amps Needed        -        158 Amps

It is much higher than any RV circuit can handle; however, it is not realistic to assume this would happen.

An example of a more realistic power use would be

It would result in a normal amp draw of 29 amps and a surge of 31 amps.

The surges would probably not happen simultaneously, so a 50 amp circuit would be able to manage this kind of power draw. If you want to run one of the other appliances, you may need to switch off the air conditioner.

Definitions Of An RV Electrical Service

The following are the definitions needed to help understand the difference between 110 and 220 volts.

  1. Alternating current.
  2. Circuit Breaker.
  3. Shore Power.
  4. The measurement of electrical current.

Alternating Current RV Electrical Service

Electrical current can be delivered in two forms.

  1. Direct Current (DC)
  2. Alternating Current (AC)

Direct Current RV Electrical Service

As the name implies, a direct current is a uniform current delivered through a circuit.

Alternating Current RV Electrical Service

An alternating current continually reverses the electrical charge.

For example, it

  1. Starts from zero voltage and grows to a maximum positive voltage.
  2. And then reverses and decreases to zero.
  3. And continues down to reach a maximum negative value.
  4. It once again reverses direction and repeats this cycle indefinitely.

An RV park offering 220-240 volt alternating current circuits is offering two 110-120 volt alternating current circuits.

These work in opposite phases, which means that as the one power source increases to +110 volts, the other circuit moves in the opposite direction (phase) to reach -110 volts. When each supply is at its peak (or trough), the difference is 220 volts.

The 220 volts (50 amp) plug has two live wires because each provides a 110-volt power supply but in opposite phases.

Circuit Breaker

There are several circuit breakers within an RV park system, starting with.

  1. At the park’s main Utility power supply.
  2. At the shore power distribution point.
  3. At the connection point in the RV.

The circuit breakers measure Amps and, as explained below, represent the amount of electricity that flows through the circuit.

If there is a power surge and the electricity spikes, the circuit breaker is designed to trip and cut the power supply, thereby protecting the electrical consumers in the RV.

The circuit breaker will also trip if you try to connect the RV to a circuit with a higher allowable amperage than it is designed to handle. For example, if you join a 50 amp circuit to the RV when the  RV is only rated for a 30 amp current.

Shore Power RV Electrical Service

Shore power is the power sockets installed at the RV park and will generally include two different style plugs, depending on whether the service is a 30 amp/ 110volt or 50 amp/220volt.

The following measurements determine the current.

There are four main measurements of current which are.

  1. Amps
  2. Volts
  3. Watts
  4. Ohms

For this exercise, we will only define the first three.

Amps Measure Speed Of The RV Electrical Service

Electrical current comprises electrons moving between the negative and positive sides of the electrical circuit.

Amps measure how many of these electrons pass a specific point on the circuit. An ammeter plays a similar road as a traffic policeman standing on the road and measuring the speed of the vehicles. The higher the average speed, the more cars can travel on the road; however, to carry more vehicles safely, the road needs to be increased in size so that it is safe to travel on it.

One ampere moving in a circuit equals one coulomb of electrical current going past a given point per second. One coulomb equals 6.24 × 1018 electrons.

In the same way, a wider road can carry more vehicles, so the size of the wire determines the number of electrons that a circuit can carry.

Electrical wire is rated according to the American Wire Gauge (AWG) measure.

Ironically the thicker the wire (and therefore, the greater the ability to carry more electrons), the smaller the AWG number. The following table details the size of wire which can carry different levels of amps.

Voltage (V) is the Energy For The RV Electrical Service

Voltage is the potential difference between the negative terminal and the positive terminal.

Voltage is the energy available to move current flow from the negative terminal, the device to be powered, and the positive terminal.

A little like gravity's effect on the water at the top of a waterfall. The top of the waterfall can be likened to the negative terminal on a battery. At the top of the waterfall, it is only potential energy. However, as the water starts to fall, gravity takes hold and moves the water downwards until it hits the ground, like the battery's positive terminal.

If the water did work on the way down, for example, it turned a turbine, some of the energy would be used to turn the blades, and therefore there would be less energy when the water reached the bottom.

Watts (W) The “Pressure” Of The RV Electrical Service

Using the waterfall example, If we were to measure the energy available (Volts) and the number of water molecules passing a specific point (Amps) per second, we would be able to calculate the water pressure.

In the same way, we can calculate the "pressure" of the electrical flow using a unit called "watts."

  1. Using this example, assuming the same amount of water was falling, but the top of the waterfall was made wider, you would reduce the pressure (because the same amount of water would fall, but over a wider area.)
  2. Comparing the water's potential to fall to the voltage. If the voltage is reduced, it will reduce the watts in the circuit (water pressure).
  3. Similarly, if you force more water over the edge of the falls, it will increase the amount of water falling, so the pressure would rise. It applies to the number of electrons passing a certain point (amps). As the amperes (number of electrons passing the measuring point), the electrical "pressure" would rise, meaning the circuit watts would increase.

There is a direct factor between the measures, and therefore if two of the measurements are known, you can calculate the third.

The calculations for each measure are

Calculating The Amps Of The RV Electrical Service

To calculate the number of amps, apply the following formula.

Assuming the circuit is

  1. 240 volts
  2. 12,000 watts

Amps = Watts / Volts.

12,000 Watts / 240 Volts = 50 Amps.

Calculating The Voltage Of The RV Electrical Service

Assuming the circuit is

  1. 50 amps
  2. 12,000 watts

Voltage  = amps / watts.

50 amps / 12,000 Volts = 240 volts.

Calculating The Watts Of The RV Electrical Service

Assuming the circuit is

  1. 240 volts
  2. 50 amps

Watts  = amps * watts.

50 amps X 240 volts = 12,000 watts