Saturday, June 10, 2023


RVelectricity: Pros and cons of the big three brands of EMS surge protectors

Dear Mike,
Do you know anyone who has tried out the EMS surge protectors from the big three manufacturers? —Fabian

Dear Fabian,
Indeed I do, and that would be me. I have sample Advanced/EMS surge protectors from Hughes, Progressive Industries, and Surge Guard in my shop and I’ve experimented with all of them.

Now, I didn’t get the opportunity last year to try to blow them up with a high-energy pulse test that can simulate a lightning strike, and that was because COVID got in the way. But I did do bench testing to see how each brand performs for Over/Under Voltage, Open Ground, Reversed Polarity, and Generator 60 Hz Frequency.


An Advanced/EMS Surge Protector is a lot more than just a bigger version of the surge strip on your office computer. The Advanced/EMS units from all three manufacturers do indeed have MOV voltage spike protection that will help keep nearby lightning strikes from getting into your RV’s electrical system.

They also continuously watch for voltage above 128 and below 104 volts, check to make sure the Ground connection is intact, and report Hot-Neutral Reverse Polarity on a receptacle. And when they find something dangerous, they shut down a big relay which removes your RV from the pedestal power, thereby saving your RV electrical system from damage.

Don’t get a basic surge protector if you can afford to spend more…

Yes, I know that you can buy a basic surge protector (without the EMS function) for less than $100. But that’s just a bigger version of your office surge strip. The Advanced/EMS versions do cost more money (maybe $275 to $400, depending on 30- or 50-amp versions), but I consider them to be well worth the investment. Even a few seconds of pedestal electricity over 140 volts can be very dangerous, and I’ve seen it go over 200 volts on occasion, which is a sure way to fry a lot of things in your RV. That’s a big dollar fix that could take months to repair.

Here they are in alphabetical order with my basic pros and cons of each.

Hughes Power Watchdog with EPO (Emergency Power Off)

Hughes is the new kid on the block. They originally started with their Autoformer voltage booster product. The Power Watchdog is not that, since it doesn’t actually boost the campground voltage by 10% like their Autoformer. But it does monitor for high or low voltage, reverse polarity, open ground and high amperage. Plus, it checks for downstream open neutral problems in your RV, a great feature for a 50-amp service. Watch Mike’s interview with Tony Barthel about the Hughes Power Watchdog HERE.

Pros: Hughes Power Watchdog

  • Their Bluetooth phone app is great and allows you to not only monitor instantaneous voltage and current draw from your RV, you can also see your total Kilowatt Hour Usage. 
  • Comes in both 30- and 50-amp versions with portable or hardwired options. 
  • You can replace the MOV module yourself in the field if it wears out from too many surges

Cons: Hughes Power Watchdog

  • That big angry dog on the outside of the case is BRIGHT when it goes red to warn you of a problem. A few of my readers also say that even the normal light is bright enough to attract attention from thieves, and have bagged it to hide the light.
  • No waterproof plug cover option available

Progressive Industries EMS (Electrical Management System)

These are the guys who started it all and coined the phrase “EMS” (Electrical Management System). Their EMS surge protectors come in both hardwired and portable versions in 30- and 50-amp sizes. While they do have a remote panel, you can mount in your RV. There’s no Bluetooth app just yet.

Pros: Progressive EMS

  • Most popular brand
  • Solid performance
  • Great replacement warranty if the MOVs wear out
  • Waterproof plug cover available as an option

Cons: Progressive EMS

  • No downstream open-neutral protection 
  • No Bluetooth interface at this time
  • Simple number warning codes you need to look up error codes on a chart

Southwire/Surge Guard Total Electrical Protection

I’ve done a lot of testing with this product line, so I understand their testing algorithms intimately. That’s also why I think their ability to shut down power in the case of a voltage problem may be the best of them. They invented the downstream open-neutral sensing, which can save your bacon on a 50-amp service if the campground or your RV neutral opens up. If that occurs, it will shut off power to your RV before the voltage can reach dangerous levels.

They do have a Bluetooth version, but their smartphone app is still in development. So if you want a remote monitor you’ll need to buy their $50 unit and stick it on the wall. Also, their MOV devices are not field replaceable when they wear out, but they do offer a replacement warranty similar to Progressive.

Pros: Surge Guard

  • EMS function also available in their Southwire ATS (Automatic Transfer Switch)
  • Full replacement warranty in the event the MOV devices wear out
  • Great voltage protection algorithms
  • Upstream and downstream open-neutral protection
  • Bluetooth remote panel available 
  • High-Joule MOV devices

Cons: Surge Guard

  • No smartphone Bluetooth app at this time
  • Non-replaceable MOV devices
  • No waterproof plug cover option available

There you have it – my take on the pros and cons of the big three brands of EMS surge protectors. I’m hoping to do some destructive testing on all three product lines this fall, so let’s keep our fingers crossed. Mikey likes big booms...

Let’s play safe out there….

Shop for EMS surge protectors:
Find EMS surge protectors on TechnoRV
Hughes Power Watchdog on Amazon
Progressive Industries EMS on Amazon
Southwire/Surge Guard Total Electrical Protection on Amazon

Mike Sokol is an electrical and professional sound expert with 50+ years in the industry. His excellent book RV Electrical Safety is available at For more info on Mike’s qualifications as an electrical expert, click here.

For information on how to support RVelectricity and No~Shock~Zone articles, seminars and videos, please click the I Like Mike Campaign.



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1 year ago

These devices DO NOT PROTECT your RV from a direst lightning strike. If that happens your RV is toast, are you if you are inside.
They do protect electrical systems (and people near those systems) from NEAR BY lightning strikes or line to line contact accidents on the utility system. Taking the magnetic pulse voltage of the equipment to ground instead of creating a side flash that could cause a fire or kill a person.

Doug Jones
1 year ago

Good Morning Mike

I just saw this article and I’m wondering what is “MOV”? I’m curious as to how you know when to replace the MOV module in the EMS that have a replaceable MOV?
Thanks for all the info you provided.

Regards Doug

Jerome Imbriani
1 year ago

I have the 30amp Progressive EMS. On last camping trip My RV plug and the EMS socket both melted badly. There was no warning and my RV never shut down. It was mid 90s and my AC was working hard. I was surprised when Progressive told me their EMS does not monitor this. Do any of the other systems warn you of a loose connection or overheating.

Tony Grigg
2 years ago

I use the Hughes Bulldog 50a in my 5ver. I have the unit mounted inside my storage bay and hardwired into my internal power line. No need to chain it, no one sees the bright bulldog face lit up. And in fact it makes a GREAT night light when I’m accessing the storage bay after dark.
This winter while moochdocking at a friend’s house in mid-Texas, I was intermittently loosing power in the RV. The Bulldog’s error code indicated an open neutral leg. A little investigating revealed a poor neutral connection on my friend’s outdoor 20a outlet. I appreciated the Bulldog protecting us and my friend was glad have discovered his issue.

William Hall
2 years ago

Mike, are the installed surge protectors the same as their uninstalled versions?

Thom R
2 years ago

I don’t always chain up my surge protector, kind of depends on what the neighborhood looks like…
When we are setting up, I want to hurry up and be done. That extra 90 seconds seems too much. I need to retrain myself and get in the habit of chaining it all the time!

Chuck Bonelli
2 years ago

Hope you video the destructive testing… I like big booms too!
p.s. Great mad scientist toon 🙂

Mike Sokol
2 years ago
Reply to  Chuck Bonelli

That’s the plan…

2 years ago

Get one and use it. Only adds a few minutes to your setup and take down time. P.S. Chain it to something solid.

Mike Sokol
2 years ago
Reply to  Tom

I agree 100 percent…

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