"RV AC ELECTRICITY"

I was surfing on the internet recently reading some of the forums on RV AC Electricity and was astounded by the confusion over AC electricity, particularly amp usage of AC electricity. This goes to show you how unless you're working with it every day, we take electricity for granted. After all , if I'm not having any problems what need is there for me to understand it?

By reading the forums the answer appears to be as soon as you purchase your first rv , start tripping a few breakers, and all of a sudden we're wondering what in the world is going on.


With rv's getting bigger, fancier, and adding all the comforts of home (and more) power requirements have naturally increased resulting in the mysterious world of 50 amp service. If you think I'm exagerating just read some of the forums.
    I use the word "mysterious because the misunderstanding is not only between 30 and 50 amp service but also many don't have a clue as to what 50 amp service actually is.
Basically most people realize you can't run two air conditioners or one air conditioner and another high amperage appliance (such as microwave or hair dryer) at the same time with 30 amp service and that you can with 50 amp's but how that is accomplished is anyone's guess. People seemed to have a basic understanding of what was going on with 30 amp service because it was pretty straight forward. You could basically "draw" or use up to 30 amps with no problem. If you go over that you would trip the shoreline breaker. People even understood if they plugged in at home into a 15 or 20 amp circuit and went over that limit a breaker would trip.

The confusion with 50 amp service seems to have arisen because most people just don't understand it.

For the purposes of this discussion it will not be necessary to get into a bunch of formulas. Most of us have a rudimentary understanding of 110 voltage. Reviewing voltage we know it is electrical "pressure" or "potential" available. Its often referred to 110, ll5, or 120 volts ac (alternating current) and I can't tell you why they can't use ONE designation except perhaps they wish they were plumbers. (There is absolutely no consistency in the plumbing trade which happens to drive me crazy!!!) Anyway if you take a voltage measurement in a regular circuit you will normally get a reading somewhere in between 110 and 120 volts. Many rv'ers keep an eye on voltage available when rv'ing because if voltage drops below 110 volts you can damage AC appliances because when voltage (pressure) goes down amperage(electrical draw) goes up. This can burn up motors and compressors so astute rv'ers always monitor available voltage particularly in high energy usage situations such as operating air conditioners in rv parks in the dead of summer

    Amperage can be described in a number of ways:

  • electrical flow to operate a "load"(appliance, motor, light, etc)
  • electrical "draw" to operate a "load"

    Every appliance(or load) has an amperage(or wattage) requirement. At the end of this report is a list of approximate amp and wattage requirements for various appliances and this is generally all you need to know in order to monitor your energy usage to keep yourself out of trouble.


Now back to the subject at hand which is 50 AMP SERVICE and why has it thrown so many into a tizzy. Quite simply 50 amp service is misunderstood and if this applies to you, you may not believe what I'm about to say. Here goes anyway!

  • 50 Amp Service is really 100 amp service
  • 50 amp Service delivers a WHOPPING 12,000 watts(volts(120) X amps(100)
  • compare this to 30 amp service(120 volts X 30 amps) or 3600 watts
  • thats more than a 3X increase with 50 amp service
  • its also why manufacturers think ( and do) charge ___________ for 50 amp service


Before you start calling me crazy and before I explain how this is accomplished (which is quite simple) there are two simple observations you can make which will make my point. The photo below has a 30 amp cord (very used) on the left and a 50 amp cord on the right. This side by side comparison illustrates that the 30 amp cord is incapable of delivering the power which the 50 amp cord does.


30 and 50 Amp Cords



No comparison is there. A 25' 30 amp chord can be purchased for around $55 and a 30' 50 amp chord will run you around $197.(find out wire gauge) That's because the 50 amp chord is much heavier than its 30 amp counterpart.



The second observation we can make is to compare a 30 amp breaker panel to a 50 amp breaker panel. (pictured below) Your 30 amp breaker panel is usually limited to 3 circuits (3 breakers plus your main breaker) or possibly 4 if there is a second air conditioner wired in .(Of course you're only going to run one air conditioner circuit at a time)


Typical 30 amp breaker panel



Now compare this to the 50 amp breaker panel. This one has around ten branch circuits. You cannot only run two ac's at the same time but a number of other things. To figure out what is on each circuit all you have to do is turn one of the main breakers off and probe the black wire coming out of each branch breaker to see which is "live" and which is not. ( Obviously the ac's are on separate circuits.)

50 amp service is what is used in many mobile home courts and is about one half of what is used in newer residential construction so you can see why 30 amp service is becoming outdated.

Typical 50 amp breaker panel


Ok, so how is 50 amp service wired? Below is a 30 amp socket and a 50 amp socket. The 30 amp socket is one circuit and if you take a voltage reading between the two flat areas of the socket (one is hot and the other neutral) you will get a reading between 110 volts and 120 volts. The 50 amp socket is actually TWO CIRCUITS( that's where the 100 amps I referred to earlier came from), two 50 amp circuits. The two flat blade areas opposing each other are both hot and if you take a reading at those terminals you will get a reading of around 240 volts. People understand that most rv's don't use 240 volt appliances (BUT SOME DO, PREVOST FOR EXAMPLE) but rv's with 50 amp service do have 240 volts at the breaker panel, they're just not used together. Simple isn't it???


30 amp socket


50 amp socket




Looking above at the 50 amp breaker panel the large black wire to the left is one 120 leg and the large red is the other 120 leg. These two wires are going into the two main breakers for this panel and even though this photo is not close enough to see each of these two main breakers are 50 amp breakers. That kind of settles it doesn't it? picture sockets Hopefully this will clarify the 30 amp vs. 50 amp confusion. If not please contact me for further clarification.


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Appliance Wattage and Amperage Consumption (Approximate)
ApplianceWatts Amps
Air Conditioner 13,500 Btu 1700 14
Air Conditioner 15,000 Btu 1950 16
Blender 300 2.5
Coffeemaker 900 7.5
Computer (desktop) 100 8
Computer (printer) 240 2.0
Converter (30 amp) 550 4.5
Converter (40 amp) 650 5.5
Converter (75 amp) 1050 8.5
Heater (electric) See wattage rating for heater 12.5
Hair Dryer 1200 10.0
Iron 1200 10.5
Microwave 450 Watt 900 7.5
Microwave 650 Watt 1,300 10.5
TV 100 .75
TV Satellite & Receiver 170 1.5
VCR 90 .75
Washer/Dryer (RV type) 1900 16.0