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Best RV Autoformer Reviewed & Everything You Need To Know

What Is An RV Autoformer?

It’s common for campers to confuse RV autoformers with surge protectors, and while they both can measure the voltage going into an RV, they do very different things.

Some autoformers like the ones in this review, are a combination of a surge protector and an autoformer.

Related Product: See how level your RV is using an App on your phone with the LevelMatePro Wireless RV Leveling System (click to view on Amazon)

Every RVer should have a surge protector.

If you travel to different RV parks and campgrounds often, it can be a good idea to get both a surge protector and an RV autoformer whether it’s a combination of both or two separate things.

Now to the question, what is an RV autoformer? An autoformer is the combination of the two words “automatic” and “transformer.”

But an RV autoformer differs from an autotransformer. Confused yet?

RV autoformers are used to increase the voltage going into your RV whenever it senses that it is too low.

Even though it’s called an autoformer it’s actually a step-up transformer or an RV voltage booster.

See Also: How To Set Up At An RV Park Or Campground For Dummies

This differentiation is important because autotransformers are illegal to use on RVs according to the National Electrical Code.

Don’t let the language fool you. RV voltage boosters like Hughes Autoformers are legal to use because they are not autotransformers, they are voltage boosters.

Why Use An RV Autoformer?

The main reason you should get an autoformer for your RV is to protect the appliances inside.

All electrical appliances are sensitive to low voltage, especially ones with motors and compressors like air conditioners, refrigerators, and microwaves.

Smaller electronics like computers are also sensitive to low voltage and can be damaged.

Low voltage causes electrical appliances like these to draw more current to keep running.

Overheating occurs and the electrical components get damaged. An easy to see example are the charging cables to computers.

They get really hot when plugged into outlets with low voltage and will wear out faster than when they are plugged into outlets with the proper voltage.

See Also: Best RV Surge Protector & EMS For 30 Amp & 50 Amp

Lots of RV parks and campgrounds have problems with low voltage.

Whether it’s from old age or high power demands, you want to protect your RV and the expensive appliances inside.

Getting an RV autoformer will help keep the voltage in the safe range so everything can keep running safely without the risk of being damaged and overheating.

Hughes Autoformers RV220-50-SP, Voltage Booster with Surge Protection,...
Power Watchdog Hughes Autoformers RV 2130-SP, Voltage Booster with...
Voltage Boost
10% (Turns On At 113V)
10% (Turns On At 113V)
Surge Protection
4,800 Joules
2,400 Joules
Pedestal Diagnostic Feature
Install Kit
Size (HxWxD)
12 x 8.5 x 5.5 inches
12 x 8.5 x 5.5 inches
35 lbs
21 lbs

Hughes Autoformers RV220-50-SP, Voltage Booster with Surge Protection,...
Voltage Boost
10% (Turns On At 113V)
Surge Protection
4,800 Joules
Pedestal Diagnostic Feature
Install Kit
Size (HxWxD)
12 x 8.5 x 5.5 inches
35 lbs
Power Watchdog Hughes Autoformers RV 2130-SP, Voltage Booster with...
Voltage Boost
10% (Turns On At 113V)
Surge Protection
2,400 Joules
Pedestal Diagnostic Feature
Install Kit
Size (HxWxD)
12 x 8.5 x 5.5 inches
21 lbs

Last update on 2024-07-24 / Affiliate links / Images from Amazon Product Advertising API

The Best RV Autoformer Reviews & Info

Hughes Autoformers RV Voltage Booster

Hughes Autoformers RV220-50-SP, Voltage Booster with Surge Protection,...

Check Price at Amazon

When it comes to RV autoformers that boost voltage and have surge protection, Hughes Autoformers are the best of the best and the most popular RV step-up transformers on the market today.

There is a 50 amp RV220-50SP (shown in the picture above) and also a 30 amp RV2130-SP version (click to view on Amazon) that has all the same features.

First off, let’s talk about the step-up transformer part. The 50 amp one has 12,000 watt capacity, just like a 50 amp RV, 5th-wheel, or travel trailer.

The total RV voltage boost can go as high as 10%.

If you need more than a 10% voltage boost to stay within safe voltage parameters (114-126 volt), do not plug in your RV, because there is something seriously wrong with the electrical system of the RV park or campground you are staying at.

The minimum usable voltage for the Hughes Autoformer is 90.

See Also: Best 12 Volt RV Lithium Battery Reviews + How To Charge

There is also a diagnostic feature.

When you plug it into the power pedestal, it will test the power going to both hot legs (only 1 hot leg on the 30 amp), and the ground and neutral connection.

After testing, the light indicators will show green if the power is safe to plug into or not.

Hughes Autoformers RV220-50-SP, Voltage Booster with Surge Protection,...

You will also be shown when the RV autoformer is boosting voltage or in the non-boosting mode.

If the voltage drops to 113 or below, the Hughes Autoformer will start boosting at 10% and the green boosting light will illuminate.

Once levels are steady and reach 115 volts or higher, the boost will turn off automatically.

On the 50 amp version, only one line (leg) will be boosted if needed to stop the voltage boost from going too high.

Not only does the Hughes Autoformer boost voltage, it’s one of the best surge protectors on the market today.

That’s why I recommend it to people who were going to buy a surge protector anyways.

It gives up to 4,800 joules of protection on the 50 amp version and 2,400 joules for the 30 amp version, which is standard for all high-quality surge protectors.

See Also: Best RV Surge Protector/Guard With EMS 30 Amp & 50 Amp

There are indicator lights that will shine green when the surge protection is functioning and red lights that will show if the surge protection unit is damaged.

Unlike a lot of other lower-quality surge protectors, the unit is replaceable.

So you don’t have to worry about needing to buy a new RV autoformer if the surge protection ever needs to be replaced.

The Huges Autoformer RV Voltage Booster is not waterproof or weather-resistant, so you will need to keep it covered when it rains.

The box is fairly small and you can put it on a block of wood and place a bucket over it to keep it dry. Or you can do what a lot of RVers do and mount it inside your RV.

This will protect it from the weather, theft, and prying eyes.

Because so many people like to install their RV autoformer/surge protectors inside their RV they sell easy to use installation kits for both and 30 amp (click to view on Amazon).

The Hughes Autoformer 50A RV Voltage Booster(click to view on Amazon) and the 30 amp version (click to view on Amazon) are high-quality, dependable RV power boosters that will protect your camper.

Whether it’s low voltage or high power surges, Hughes Autoformers has you covered.

Every RVer should have a surge protector, no matter how often they hook up to electricity.

A dangerous surge only needs to happen once to fry the electrical system and appliances.

Low voltage is the other killer of electrical appliances and you may as well have that protection as well.

If you camp in hot places during the summer and need to run one or even two AC units, an RV step-up transformer like Hughs Autoformer’s is a must-have.


  • High Surge Protection
  • Pedestal Diagnostics
  • 10% Voltage Boost
  • Can Be Mounted Inside RV
  • Compatible With Adaptors
  • 50 & 30 Amp Options
  • Will Protect RV Appliances


  • Not Waterproof
Large RV park with lots of RVs means an RV autoformer may be needed
A crowded RV park in the summer means more people using lots of power. An RV autoformer will help keep your RV AC from getting damaged.

What To Look For In An RV Autoformer

Surge Protection

A surge protector is recommended for all RVers who plug into any kind of electrical power.

If you’re going to get an RV autoformer, you might as well get surge protection as well.

You can use a separate surge protector with an RV autoformer but the easiest thing to do is to get a combo like the Hughes Autoformer that has both.

Pedestal Diagnostic

Voltage and power surges aren’t the only things you need to protect your RV electrical system from when connecting to power.

A bad ground or neutral connection can damage as well.

The Hughes Autoformers has a diagnostic feature that not only tests the power lines going into the RV autoformer.

It will also test the ground and neutral connections as well to make sure they are safe to use.

Install Kit

Most RV autoformers are not waterproof or even weather resistant. They are also a common target for theft and should always be locked up.

To help with both problems, you can get an RV autoformer that has an install kit option you can use to mount it inside a storage compartment of your RV.

This will protect it from the weather and theft.

Frequently Asked Questions About RV Autoformers

How do I use an adaptor with an RV autoformer?

You can use adaptors to plug 50 amp RV autoformers to 30 amp power or vice versa.

Just make sure you plug the adapter into the power outlet first, then plug in the RV autoformer, and then the RV.

Are RV autoformers illegal?

An RV autoformer is technically a step-up transformer that is made to boost the voltage. These are legal. What’s illegal is an autotransformer.

Some people confuse Hughes Autoformers RV voltage boosters with autotransformers because of the name Hughes Autoformers.

Their voltage booster is not an autotransformer, it’s a booster, and it’s legal to use with an RV.

You can read a statement put out by Hughes Autoformers here.

That being said, some RV parks do not allow voltage boosters. Be very careful when staying at these kinds of places.

They may not want people using RV autoformers because they have a weak and possibly unsafe electrical system.

What is the right sequence to use an RV autoformer with a surge protector?

When using an individual RV autoformer with a surge protector, you plug the autoformer into the pedestal first, then the surge protector, then the RV.

If you plug the surge protector in first, the low voltage from the pedestal will cause it to keep shutting off.

Because you plug the surge protector in after the RV autoformer hard-wired surge protectors can be used with RV autoformers.

What do I do if my RV autoformer is boosting voltage too high?

If your RV autoformer is malfunctioning and boosting the voltage so much that the autoformer switches off (usually around 130 volts) you may have some loose wiring in your electrical connections.

Turn off all the power to these cables and plugs and check each one to make sure your wires are tight.

If this doesn’t solve the problem, your RV autoformer may require servicing.

Most companies recommend sending the autoformers back to them to be fixed by their own knowledgeable professionals.

Will an RV autoformer decrease the voltage for other RVs in the campground or RV park?

If the voltage in an RV park or campground is low, using an RV autoformer will boost the voltage for your RV, but it will slightly decrease the voltage for the other RVers that are plugged into the same system as your RV.

That’s a big reason substandard RV parks and campgrounds don’t like RV voltage boosters.

If everyone is using an autoformer, it could blow their already stressed system.

There’s a lot of debate on if using an autoformer is ok or not in crowded RV parks and campgrounds.

On one hand, it isn’t ok or sometimes even legal for businesses like these to be supplying low voltage as it is a safety issue.

Using an RV autoformer is only protecting your RV and the expensive equipment inside.

On the other hand, using an RV autoformer in a campground or park where there is very low voltage from heavy electrical demands will only make the problem worse for other RVers.

It may even be what pushes the voltage so low that it damages the sensitive electronics in other RVs that don’t have an RV autoformer.

My suggestion would be to look at each situation and go from there. If you can avoid RV parks that have a very low voltage that’s below 114 volts, you should.

If there are only a few RVs plugged into the same system, then your RV autoformer shouldn’t make that much of a difference.

If the voltage is sitting right at the 114-volt line and there are lots of RVs plugged into the same system, using your autoformer may not be a good idea.

In the end, the decision is up to you and sometimes the RV park. Make sure you check with the rules of any place you stay. They may not allow RV autoformers.

How do I quickly test the voltage in an RV outlet?

To make sure your RV autoformer works properly or to test the voltage in the outlet to your RV, you can use a few different devices, like multimeters and voltage testers.

A simple, easy to use gadget is an outlet AC 120 volt meter like a Digital 120 Volt Meter (click to view on Amazon).

All you have to do is plug it into an outlet in your RV and it will tell you what the current voltage is.

Don’t leave this meter plugged in all the time. Only use it when you want to test the voltage in an outlet.

Should I use a surge protector if I use an RV autoformer?

Yes, you don’t technically have to use a surge protector if you use an RV autoformer, but you should always use a surge protector anyway.

Even if you don’t use an RV autoformer, a surge protector should be used to protect your RV from power surges caused by things like lightning and faulty wiring.

See Also: Will A 50A Surge Protector Work In A 30A Outlet?

Can you use an RV autoformer with a generator?

This is a tough question to answer. An RV autoformer should work with a generator because the generator shouldn’t be putting out low-voltage.

If you have a hard wired RV autoformer, you may need to do this.

If you have the option to not plug your autoformer into a generator, then you should just not plug it into the generator instead.

If the RV autoformer is an autoformer and surge protector combo, your generator might not work with the surge protector.

For information on how to get a generator to work with a surge protector, check out this article here.

See Also: The Best Camping Gas Generators That Will Run Your RV AC

Have any more questions about RV autoformers (voltage boosters)? Leave a comment below.

by Jenni
Jenni grew up in a small town in Idaho. With a family that loves camping, she has been towing trailers since a very young age.

2 thoughts on “Best RV Autoformer Reviewed & Everything You Need To Know”

    • Hi Ronnie,

      Are you plugging the 50 amp autoformer into a 30 amp power supply or plugging your 30 amp RV into a 50 amp autoformer? Either way, I think it should be fine but you will need different adapters depending on what you are plugging the autoformer into.


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