How to Calculate the Current Load Your Appliances Place on Your RV's Electrical System

Updated on May 12, 2019
Don Bobbitt profile image

Don has been an avid traveler and motorhome owner for most of his life and shares his experiences with valuable tips.

A typical motorhome kitchen (a Fleetwood Bounder) showing some common appliances
A typical motorhome kitchen (a Fleetwood Bounder) showing some common appliances | Source

Your RV Electrical Circuits and Breakers

All RV's, regardless of the type and size, are designed with cabling systems for connecting to external AC power sources.

These connections and systems inside the RV support not only the built-in electrical equipment, but also the numerous other appliances the owner may want to use while traveling and camping.

Your RV is wired so that all of the 110-VAC power (110 volts AC power) used inside the RV goes through the main breaker panel. These breakers are rated at different current limits to protect the equipment inside the RV, and thus prevent overloading of the RV's electrical circuits and wiring.

If one or more of your AC-voltage circuit breakers "kicks off," that means the current exceeds what your circuit was designed for.

When Overload Conditions Occur

When a circuit breaker in the RV kicks off from an overload while you are camping, it's always a surprise.

Some of the RV's breakers are dedicated to specific pieces of electrical equipment inside the RV, such as the air conditioner, refrigerator, televisions, and other high-current devices. Other breakers are general circuits that provide power to banks of 110-VAC receptacles placed in the RV for the convenience of the camping family.

So, when a breaker does activate, the owner needs to consider what may have caused the breaker to kick out.

If an air conditioner's breaker kicks out, you know what to do to determine the problem. You will generally check your external source power first.

But, when you have one of the general circuit breakers kick out, you need to look at the problem a little differently.

110-VAC Appliances and Personal Devices Draw Current

When a camping family travels, they tend to carry quite a few electrical devices with them that operate directly on 110-VAC, or often operate on batteries that require the use of chargers that operate on 110-VAC.

Common personal devices that we plug into our RV's receptacles include cell phone chargers, modems, WiFi boosters, personal computers, flashlights, and portable stereos. All of these will draw some level of current even while not charging a device or operating.

Most campers also use home appliances that draw higher current, including coffee pots, mixers, electric frying pans, electric crock pots, toasters, portable ice makers, and other higher current drawing home appliances, all of which add to your load on your breakers.

All of these devices draw some amount of current while operating, and they, like most common appliances, will typically have a label that lists the maximum wattage the appliance will use when it is operated.

But many other devices will only list the maximum current the appliance will draw and not the wattage.

When one of your breakers kicks out, you need to figure out things like:

  1. What 110-VAC equipment you using at different times of the day,
  2. How much current each of your devices draws when operating, and
  3. How you can manage their use so that everyone can enjoy their camping experience while not disrupting the power available to everyone.

How to Convert Maximum Watts to Maximum Current

When a breaker goes off, especially a main breaker, you want to figure out how much total current you are using. A certain level of current is what sets off the breaker.

The simple thing to do is look at everything you have plugged into a circuit of receptacles and add up the maximum current that circuit might be subjected to if everything is plugged in and operated at once.

When you see an appliance with a label that only lists the wattage, you may need to figure out the actual maximum current it will draw.

Use This Formula to Calculate Current

There is a simple formula for converting the maximum wattage rating of an appliance to a maximum current number.

A = W/V

Current (A or amps) equals watts (W) divided by voltage (V), or more simply, A=W/V.

For example if you have a coffee pot that is rated at 1500 watts, you can easily calculate the maximum amount of current that coffee pot will draw by dividing that wattage number by 110 volts, which is the voltage available on your standard AC receptacles in your RV

So, if you divide 1500 (watts) by 110 (volts) you end up with the maximum current the coffee pot will draw, or in this case, 1500/110 = 13.6 Amps.

Now remember this is the maximum current the coffee pot will draw. In reality, it will draw a lot less when it is just keeping your coffee warm, but when it is perking the coffee, it can be operating near this maximum current limit.

And, considering that your circuit breakers are usually 20-Amp breakers, this load from the coffee pot, while it's actively perking, would leave with an additional current capacity just 6.4 amps (20 - 13.6) on that circuit of receptacles.

When you understand this way of calculating AC voltage limitations, you will be able to avoid plugging in two high-wattage or high-current appliances on the same circuit and operating them both at the same time.

A typical RV appliance, an electric frying pan
A typical RV appliance, an electric frying pan | Source

Appliances and the Power They Use

As we have mentioned the appliances used in your RV, both the built-in ones and those you can plug into a receptacle, all operate on your RV's 110-VAC power system.

You should know just how much current each appliance draws when it is in operation and the table below is a good quick reference for the most common appliances and how much current they can draw.

Typical Appliances and How Much Current They Draw

EQUIPMENT
Max CURRENT
RV Air Conditioner (Start-up)
12-15 Amps
RV Air Conditioner (Running)
3-6 AMps
Chargers (small electronics)
0.5 to 1.5 Amps
Coffee Pot (Brewing)
7-9 Amps
Coffee Pot (Warming)
1-3 Amps
Crock Pot (Cooking - High)
3-5 Amps
Crock Pot (Warming)
1-2 Amps
Food Processor
5-8 Amps
Frying Pan (Cooking - High)
7-10 Amps
Hair Dryer (High)
7-12 Amps
Heater, Electric (Small Space)
4-10 Amps
Iron (High)
8-10 Amps
Microwave Oven (Standard)
7-9 AMps
Microwave Oven (Convection)
7-14 Amps
PC, Notebook)
1-3 Amps
Refrigerator (2-door medium size)
2-4 Amps
Toaster
8-10 Amps
TV, Digital
1-3 Amps
Vacuum (Hand-Held)
2-4 Amps
Water Heater (6-gallon, heating)
8-12 Amps
Appliances used in an RV

Explaining Watts, Volts and Amps

This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.

Questions & Answers

    Comments

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      • Don Bobbitt profile imageAUTHOR

        Don Bobbitt 

        4 months ago from Ruskin Florida

        Liz Westwood - hanks so much for the positive feedback.

        I'm so glad that I was able to help you with this information.

        Have a Great Day!

        DON

      • Eurofile profile image

        Liz Westwood 

        4 months ago from UK

        I found the current table especially useful in this article.

      working

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