30 Amp vs. 50 Amp Power Cords – Which One is Yours?

Terry Cooper Texas RV Professor

Did You Know? – More Facts from America’s RV Expert

30 Amp vs. 50 Amp Power Cords – Which One is Yours?

Why is it you can only run one air conditioner at a time on the  30 Amp power cord but if you have the 50 Amp power cord you can operate both air conditioners?

Then we hear other RVers use the terms Amps? Volts? Watts? What does all this mean?  You just want to sit and enjoy the scenery but instead you are sitting in the dark?  How can you determine the limits of your RV electrical systems?

There are 3 electrical systems in your RV

• 12 Volt DC (direct current or battery type) that runs the exterior running lights, stop lights and turn signals of your coach.  On a trailer they are powered through the 7 way pin connector from your tow vehicle. On a motorized unit they are powered by your chassis alternator and battery just like your car.
• 12 AC  Volt (direct current or deep cycle battery type) that powers all the 12 volt lights, fresh water pump, circuit boards for your appliances, propane detector, room slide outs and powered leveling jacks. The converter (fancy battery charger) that takes 120 volts AC like we have at home wall receptacles and changes it to 12 volts DC for the deep cycle battery.
• 120 volts DC (alternating current like we have at home) that powers the air conditioner, microwave, electric element in the water heater, ceiling fans and wall receptacles and the AC to DC converter.  This 120 Volts AC gets its power from the 30 or 50 amp power cord we plug into the pedestal shore power.

Most electrical products have a label or plate on them that list voltage, amperage and sometimes the watts it will use.  What does all that mean?

Voltage – is the “push” that the electricity has.  Voltage is the same to electricity that water pressure is to a water system.  Voltage is either 12 volts DC (direct current) or 120 volts AC.

Amperage - is the flow of electricity.  Amperage is the same to electricity as gallons of water flow is to a water system.  The size and length of the wire carrying the amperage or current determines how much flow we can have.

Wattage or Watts – is the power of the work that can be done.  Watts is figured by taking the voltage and multiplying it by the amperage.

We call the Wattage or the Power of a device.  We rate our generators by the wattage they put out.

Recreational Vehicles come with one of two power cords.  the power cord is either rated at 30 amp or 50 amp at 120 volts AC.

50 amp & 30 amp Power Cord

So if you Rig has a 30 Amp power cord, you will have a 3,600 Watts or 3.6 KW (kilowatts) to run all your 120 volt AC appliances.

The 30 Amp power cord has a black wire as it power leg, white wire as its neutral leg and a green ground wire.

If you Rig has a 50 Amp power cord, you will have 12,000 Watts or 12 KW (kilowatts). Yes you read that correctly….12,000 Watts of Power available to use.

The 50 Amp power cord has 2 hot or power legs.  One is black and the other is red.  Each hot leg is capable of carrying 50 Amps.  One white wire is the neutral and the other wire is the green ground wire.

Typically, motor homes and 5th wheels will have the 50 amp power cord to handle their power requirements.  It is the ‘extra’ power that allows you to operate that 2nd air conditioner.

It is surprising how fast your AMPS add up which cause your circuit breaker to trip. Sometimes the individual circuit breaker for those powers appliances will trip other times it is the main circuit breaker that goes.  When you locate that tripped ciricuit breaker you flip it to the OFF position then back to the ON position.

Typical Power Requirements for your RV Devices

Air Condition – 15,000 BTU                       12.5 amps x 120 volts= 1,500 watts

(your air conditioner will somtimes pull 20 to 30 amps to get started)

Electric Water Heater – 6 gallon               12.5 amps x 120 volts= 1,500 watts

Microwave Oven                                             12.8 amps x 120 volts= 1,536 watts

Electric Coffee Pot                                                9 amps x 120 volts= 1,080 watts

Toaster                                                                   10 amps x 120 volts= 1,200 watts

Hair Dryer                                                             10 amps x 120 volts= 1,200 watts

TV                                                                               2 amps x 120 volts=     240 watts

Dirt Devil hand vacuum                                    2 amps x 120 volts=     240 watts

Electric Frying pan                                          10 amps x 120 volts=  1,200 watts

Iron                                                                        10 amps x 120 volts=1,200 watts

Food Processor                                                     6 amps x 120 volts=  720 watts

Crock Pot                                                              1.5 amps x 120 volts=   180 watts

Heating Pad                                                           .5 amps x 120 volts=      60 watts

Take a minute and  figure how much power you are using. It is suprising how fast it adds up and you can trip your breaker and be in the dark.

We must become good managers of our usage so we can enjoy the RVing Lifestyle.

It’s our job to help you keep your wheels rolling…we’ll see you down the highway!!!