A 30 Amp to 50 Amp Adapter – A Good Idea?

There is often confusion about what happens when you try to use a 30 amp to 50 amp adapter (sometimes called a “dogbone”) at a campground pedestal. Actually, there is confusion when any adapter is used to adjust the electricity provided to an RV. But in this article we will discuss whether or not you should use a 30 amp to 50 amp adapter. And we will explain what happens when you do.

A 50 Amp RV Electrical Service – What Does It Mean?

If you have an RV with a 50 amp electrical service it means that you have a thick and heavy electrical cord. And at the end of that cord you have a 4 prong 50 amp plug. So what does all those prongs do? And why is the cord so heavy?

A 50 amp RV electrical service comes with 2 wires that are rated to supply 50 amps of power to the RV. Then there is also a neutral wire and a ground wire. That makes up all four prongs on the plug. And because wires that are rated to carry 50 amps are large, the cord becomes very heavy.

Essentially, you have 2 legs of 50 amp electrical service going into the RV. That is a lot of power. And if you multiply the amps by the total volts, you get the total power available to you in watts. In other words, the wattage figure that you get tells you how much power can be consumed at one time safely. So two legs of 120 volts equals 240 volts. If we multiply that by 50 amps that each leg can carry, that leaves us with 12,000 watts. This means that a 50 amp RV electrical service can run devices that total up to 12,000 watts of power simultaneously. And in the real world that means that you can run a lot of devices and appliances without overloading the service.

30 Amps To 50 Amps – What Happens?

So when you plug your 4 prong 50 amp power cord into a 3 prong 30 amp service, what happens? Well obviously, one leg of power has been taken away. This is because all electrical services need a neutral and a ground wire. And the positive wire has been stepped down to using only 30 amps at the pedestal.

A comparison of the 4 prong 50 amp plug and the 3 prong 30 amp plug

So does this create any problems for your 50 amp RV electrical service? Not at all. This is because the adapter adjusts the power going into your RV to use only 30 amps. And since 30 amps is lower than 50 amps, nothing will be overloaded. This is because the wiring used for 50 amps is much larger than what is used for 30 amps. If someone tried to run 50 amps through 30 amp wires, that could be a problem! But not the other way around.

30 Amps To 50 Amps – What’s The Difference?

So it is safe to use 30 amps of power going into an RV that has a 50 amp electrical service. But what does that mean in power usage? Well, now you only have one leg of 30 amp power times 120 volts. And that means that your total usable power at one time is only 3600 watts. What a drop in simultaneous usable power.

So for an RV that has a 50 amp service, you probably have a lot of power hungry appliances. You may have 2 or more air conditioners, a microwave, a washer/dryer setup, and more. If you now only have less than a third of the usable power going into the RV, adjustments must be made. This means that you probably can only safely run one air conditioner at a time. And you may have to limit how many other power hungry devices you use simultaneously. In most cases you can still use them, just not all at once.

It may take a little fiddling around with to determine what can be used and when, but you will eventually get it. Every RV is a little different, so you will learn where the limits are for your particular rig. Obviously if the main power fuse is tripped, you have gone too far. So it’s best to try to stay on the conservative side to prevent that from happening in the first place.

I hope this has cleared up some of the confusion about RV amp ratings in the RV and at the pedestal. Have safe and happy travels my friends!

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