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Does a Surge Protector Provide Enough Protection?

| Updated Jun 20, 2023

While the use of a surge protector does have merit, it protects your equipment from only one of a wide variety of possible electrical problems.

An electrical surge – at least in terms of what a surge protector will protect against – is a sudden and large (generally huge) increase in voltage, oftentimes of only a very short duration – maybe only milliseconds.

It’s the type of surge caused most often by lightning hitting electrical equipment or by certain failures – or faults – within the electrical system itself.

A surge protector may or may not protect against any particular surge.

Different surge protection devices have different ratings.

Having a surge protector in place is better than having nothing at all. But, does a surge protector alone provide adequate protection?

There are a variety of other electrical malfunctions that can be identified with a simple outlet tester.

An EMS (Electrical Management System) device can protect against additional damaging conditions that a surge protector will not protect against and that an outlet tester will not detect.

Let’s start first with the very basics of 120V AC power, the type found at home and in your RV.

There is a hot wire (the source of the electricity), a neutral wire (the return path to the source of the electricity, thus making a complete circuit), and a ground wire, which is provided as a safety measure and will route the power in the circuit to ground (literally into the Earth) in the event of a wiring failure.

surge protector tester
tester for an outlet

A tester like the one shown above will test an outlet and indicate if there are wiring problems present among any of the three wires mentioned above and their associated connections:

  1. Open (disconnected) ground wire
  2. Open neutral wire
  3. Open hot wire
  4. Hot and neutral reversed
  5. Hot and ground reversed
  6. Proper and normal connection

In this photo, the tester is displaying a normal outlet condition.

surge protector tester
In this photo, the tester is displaying a normal outlet condition.

In this photo below, the tester is indicating that there is an open ground (simulated by using an extension cord with only two prongs). Only the center indicator is lit.

surge protector tester
tester shows an open ground

The photo below reveals that the tester has detected a reversal between the hot and the neutral wires. The left and center indicators are lit.

This can be a very dangerous condition, as a wire that one would expect to be dead (e.g., on the neutral side of an outlet) may actually be hot. In other words, the wiring is backwards!

surge protector tester

More Surge Protector Abnormalities

Additional abnormal conditions can be present and are not necessarily unsafe for the occupants of the home or the RV, but over time can be very bad for the equipment, particularly for refrigerator and air conditioning compressor motors.

The following abnormal conditions must be protected against – high or low voltage and high or low frequency.

Most EMS models will protect against abnormal voltage conditions, and some also protect against abnormal frequency conditions. A surge protector will not protect against any of these four conditions.

It seems obvious that high voltage is a bad thing.

Just as high water pressure will rupture a water hose, high voltage will damage electrical equipment.

But why is low voltage a bad thing?

Electrical components run on power (watts), which is a combination of both voltage (volts) and current (amperes, or amps). At proper voltage, an electrical device, especially a motor, will draw enough current to operate properly.

As the motor is being asked to do more work, it will draw more current. If it becomes overloaded, it will draw too much current and the circuit breaker will trip, thus protecting both the motor and the wiring.

Some more advanced motors will even have internal protection devices that trip and reset automatically.

Let’s say the voltage at the campground is low. The motor will start to draw enough current to still do the work it is being asked to do. As the voltage drops, the motor will draw more and more current.

Current is what causes the motor to heat up. If the motor runs for an extended period of time at low voltage and high current – but not high enough to trip the breaker – it will heat up too much and damage itself.

However, this damage may not occur right away. Repeated conditions of low voltage will cause the motor to damage itself little by little, until it eventually fails.

An EMS device senses this low voltage condition and will trip the power at a preset voltage to prevent motors from damaging themselves.

What about frequency?

surge protector

The standard electrical power utilized throughout most of the world is alternating current.

In the US and Canada, power is delivered to the home at 120 V ac and 60 Hz (the abbreviation for Hertz, which stands for cycles).

In Europe, the standard is 240 V ac and 50 Hz.

The frequency is simply a reference to how many times per second the voltage alternates, hence the term alternating current. (The voltage and the current actually both alternate.)

Many devices depend upon that 60 Hz as a timing reference in order to properly do whatever they do.

Electric wall clocks, electric light timers, traffic signal timers, telephone company switching equipment, radio receivers, etc., all depend on a very steady and accurate 60 Hz as a reference so they can, in turn, remain accurate. (Equipment that is more modern tends to utilize internal timers or reference signals from the GPS satellite system for high accuracy timing.)

The fact that so many devices need reliable 60 Hz power is the reason the non-inverter type generators have to run at 3600 rpm (revolutions per minute) regardless of how much load is on them. If they only ran at 3000 rpm, the frequency would only be 50 Hz.

What about high or low frequency?

A high or low frequency condition might not be damaging to the particular device, but it could cause the device to act improperly or it could damage the equipment that the device is controlling.

We know someone who once used the heat disinfection method to clean his contact lenses. The contacts were placed into a container which was then placed into a heater.

A button was pressed and the timer circuit would shut the device off after the proper amount of time.

On a trip to Europe, a voltage converter was used to convert from 240 V ac to 120 V ac, but the device was not made to change the frequency, which is only 50 Hz in Europe.

The timer didn’t work properly. It didn’t shut the device off at all. That overnight cooking was bad for the contacts!

To summarize, yes a surge protector is good, an EMS is better, and an EMS that also protects against abnormal frequency conditions is better still.

Regarding that circuit tester shown above, once it is known that the RV is plugged into properly wired shore power, as determined by an EMS device, it is an excellent idea to go around and check all the outlets in the rig periodically.

Unlike a home, the wiring in the rig is subjected to all the vibrations and temperature variations that come along with the RV life.

Insulation on wires can rub through and expose bare wires, connections can become loose, and any of the dangerous conditions already mentioned can develop over time, conditions that may be harmful or fatal, and must be avoided by taking the proper precautions.

And if you have some important things plugged in – you might want to review this post again and get it organized.

Here are a few links that may help you prepare for your next RV trip

If you buy something through our links, we may get a small commission at no extra cost to you. It helps keep our lights on so we can continue to provide helpful resources for RVers. Read our full affiliate disclosure here.

RV Surge Protector 50 Amp Smart Kit

Progressive Industries 50 Amp Portable RV Electrical Management System Surge Protector

RV Surge Protector 30 Amp Smart Kit

Hughes Autoformers PWD30-EPO, 30 Amp Spike Power Watchdog, Shut Off

Did you find this helpful and educational?

Let us know in the comments.

Does a Surge Protector Provide Enough Protection? 2
Mike and Jennifer Wendland

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Mike Wendland

Published on 2021-11-14

Mike Wendland is a multiple Emmy-award-winning Journalist, Podcaster, YouTuber, and Blogger, who has traveled with his wife, Jennifer, all over North America in an RV, sharing adventures and reviewing RV, Camping, Outdoor, Travel and Tech Gear for the past 12 years. They are leading industry experts in RV living and have written 18 travel books.

7 Responses to “Does a Surge Protector Provide Enough Protection?”

December 25, 2021at6:15 am, Merry Christmas! | RV Lifestyle said:

[…] Does a Surge Protector Provide Enough Protection? […]


November 16, 2021at5:02 pm, Steve Coyle said:

Thanks for the info. I am upgrading immediately to a 30 amp watchdog from the standard surge protector we’ve been using.


November 14, 2021at3:34 pm, Susan Shaver said:

Would it be safer to just use 12 volt appliances? Are there protection devices for 12 volt?


November 14, 2021at11:50 am, Bob Hoak said:

Thanks for the info. One of the first things I bought when I got my Thor Tellaro in December is last year was an EMS and felt in good shape. But during a thunder storm at a KOA, we had a power outage for a couple of hours. When the power returned the AC wouldn’t work. Being a newbie, it didn’t occurred to me to check the breaker in the van. Thanks to a response from a question on a Facebook, I checked the breaker and it had tripped. It indicated to me that even the EMS wasn’t enough. Next time I loose power at a camp site, I will turn off the breaker at the head end and turn it back on after the power returns.


November 14, 2021at9:53 am, Elizabeth Cashdollar said:

We have Hughes Bull Dog! It saved our RV! It was a pretty new park (3 years old) and the breaker was bad. We plugged in and turned on breaker. Bull Dog stopped damage to our RV but was damaged as a result. DH took pictures, called Hughes, and they sent out a brand new unit! I am so thrilled with it I want to buy a 30amp version for when we can only get 30amp service.


November 14, 2021at8:37 am, Jordan Cait said:

Hi Mike and Jen,
Thanks for the article. Do you use an EMS? Is there a specific EMS that you recommend?


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