Friday, June 2, 2023


RV Electricity – Can I add a second surge protector?

Dear Mike,
Thanks for your No Shock Zone articles! I am a big fan. I have a technical question based on an issue raised by a fellow camper. I have a Progressive Industries Surge Protector (EMS-HW50C Portable Electrical Management System) on my 50A diesel pusher, and I also use a Camco Dogbone RV Circuit Analyzer with integrated surge protection and fault indication (125/250V 50M/50F Amp) for use at the pedestals.

I got the Camco circuit analyzer primarily as a way to monitor the quality and safety of the power of the pedestal, but the unit also provides surge protection. I’ve had a fellow camper suggest that putting a second surge protector on the pedestal is a bad idea, since I already have a surge protector on the rig. Is putting a second surge protector at the pedestal okay, or a bad idea? —Michael C.
Dear Michael,
Actually, it’s a very GOOD idea. You’re adding additional joules of surge protection at the pedestal, which will also help keep lightning spikes out of the inside of your RV. Plus you can use the portable surge protector to do a preliminary check of the campground power BEFORE you accept the campsite….
However, for any of you who don’t have an intelligent/EMS surge protector like your EMS-HW50C which checks for high and low voltage as well as open grounds, let me suggest that instead of something like a basic Camco circuit analyzer, you get an intelligent surge protector for the pedestal such as the Surge Guard 34950 (50-amp) or 34930 (30-amp) unit. This will not only increase the joules of spike protection due to the extra MOV devices, it will add downstream open-neutral testing and shutdown on the 50-amp version. 
As a power precheck before-making-camp procedure (before you pull in your RV, level it and connect up the water, etc.), I’m recommending that everyone first use a NCVT (Non Contact Voltage Tester) such as  the Southwire 40116N to check the campsite pedestal to make sure the box itself doesn’t have a stray voltage. (Yes, I’ve had several emails in the last month with this really dangerous condition.)
If the pedestal does have a stray voltage, DO NOT accept the campsite and move on. If it’s OK (shows no voltage on the outside of the pedestal box), then plug in your intelligent surge protector and check the outlet for open ground, reversed polarity and reasonable voltages (102 to 132 is considered acceptable, but I think a range of 105 to 128 is safer). If the voltage is a little low you might be OK using this pedestal as long as you don’t run hot plates and air conditioners. And if the polarity is reversed you’re still probably safe, but the campground should be notified and repair the problem quickly.
However, if the outlet ground is open, then DO NOT accept the campsite and ask to move to another one after notifying the campground of the problem. Bypassing your surge protector on a pedestal that has an open or hot ground is putting your life and the lives of anyone else touching your RV in danger, so please take this seriously. 
Next week I’m going to post a cleaning procedure for any campground pedestals that were in the flood path of Hurricane Florence. No, you can’t just wait for the outlet to dry out and plug in. Any pedestal that’s been underwater needs to be properly cleaned and tested before being put back into service. 

Let’s play safe out there….


Mike Sokol is an electrical and professional sound expert with 40 years in the industry. Visit for more electrical safety tips. His excellent book RV Electrical Safety is available at For more info on Mike’s qualifications as an electrical expert, click here.



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4 years ago

I have a Progressive EMS-PT30X which I plug into the pedestal before I plug my shore line. Is there a 2nd surge protector (per Ernie Russell’s msg) that I am supposed to use?

I purchased my first MH this last June and have been reading as much as I can to properly maintain my 2016 Leprechaun and do things safely. At times I am out of my element so I know I won’t be able to take care of all repairs and upgrades myself. Wiring and electrical systems are areas best left to the pros in my case.

I’m loving my MH and mostly travel by myself.

4 years ago
Reply to  Mike Sokol

I do have a Klein NCVT-3 which I use and from now on I will wait to plug the MH into the surge protector. Thanks!

Ernie Russell
4 years ago

Mike, your recent article on adding a second surge protector made me think of my trip a few weeks ago. We pulled into rural Maine late one evening. As an aside, we started RV ing in 2011 with a 30 amp trailer. For this I bought thought was a state of the art SurgeGuard 34830. In 2015 we moved to a 50 amp trailer for which I bought what I thought was a state of the art SurgeGuard 34850.

Back to Maine. After the usual mix ups at the CG, we ended up in a 30A site so I plugged in my 34830 plugged the trailer in and powered up the pole, knowing that Surge Guard had my back. Nothing! Upon inspection I had a red light and the message “Reverse Polarity”. No problem. I told the manager and he came out and reversed the polarity at 9:30pm, while I watched. Plugged the Surge Guard in again and once again no power. This time low voltage. We changed sites and had power.

The next day we drove to Lubec for a week. This redefines rural. 4 1/2 days later our 12V dies. With No help available I called my mobile service guy in GA and after my description he thinks my batteries are dead. I carry a charger and he was right. Now to find out why. No blown fuses or circuit breakers, so I call WFCO for help. They advised there are 2 fuses on the converter that protect against Reverse Polarity. Where have I heard that before?

Problem solved, but why? I then re-read my info sheets from the Surge Guards. Turns out it is the same sheet for both products. And there it says that the 50 amp unit blocks reverse polarity and the 30 amp passes it, but with a red light. Thanks a bunch!
On the way home I stopped at Hershey and talked to Surge Guard. Typically, they had a bunch of new hires who didn’t know any history but assured me that the new ones don’t do that. And I can’t solve my concerns for a 2nd $800 investment in 2 new units.

So, all this to say that in your article you mention that we are probably safe with reverse polarity. Of course you are right, but your readers need to plug their protection into the pole and let it go through the countdown before plugging their rig into the protection.

Thanks for all your work and writing on our behalf.

steve roland
4 years ago

I asked you a while back about having more than one ground rod at a residence and you were going to address it. I think I missed your assessment. Could you direct me to your response? I can give more details of my specific setup if it helps.

J anne
4 years ago

I have had damage to electronic equipment from reverse polarity so I don’t think the probably be okay statement is wise in your article.yes fine for many trailers etc but not for all! I learned the hard way!

John Snell
4 years ago

The youtube videos regarding checking pedestals doesn’t use a non touch stray voltage checker, which I have. Do you check the outside of the pedestal before you plug in as you would the outside of your rv after you plug in.?

Kirk Locus, Canandaigua, NY
4 years ago

Another great article Mike. Thank you for all of these!

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