That’s what an EMS is for…

jsb5717

Senior Member
RV LIFE Pro
Joined
Jul 16, 2017
Posts
3,325
Location
Milwaukie, OR
We are currently at Grand Canyon Village RV Park. We pulled in yesterday afternoon and set up. During the rest of the afternoon our EMS cut power to the coach twice. After the second one I checked and the power was at 126/127 volts. The EMS was allowing this voltage but it was clearly moving around a bit and must have spiked a little higher a couple times…tripping the EMS.

Although it’s annoying to have the power cut I was happy that the EMS was doing its job. I don’t know if the power ever spiked high enough to actually hurt anything or if anyone here had any issues but I feel better knowing the the system works and prevents electrical harm.
 
I have a progressive EMS. One time in Northern Idaho (park was half full of Canadians!!) we got a spot. Most sights are long term - whole summer. My EMS kept cutting off my power. I think from too low voltage. Turns out the people in that site before me were visiting their parents in a nearby site. Neighbors told me his rig was having a lot of problems too. I finally just turned off the A/C when it was hot in the afternoon and visited my friends! Then when temps dropped later in the day it would work again. Think it saved my A/C and tv, etc.
Another story = when I first started out, we stopped at a rv park along I80 in Nebraska out in the country. No EMS at the time. I think my A/C and tv blew out due to something either high or low voltage. As soon as I got home I bought an EMS.
 
You must not travel to the hot part of the country!! In hot country parks, in the middle of the afternoon when everyone has the A/C going, the voltage drifts down and at around 106 or 107 mine shuts down. And with everyone running A/C, it gets down that low fairly often.
 
I tend to frequent a couple of crappy power parks. The Progressive cuts it off, right now, at 104V. I recently stayed at a park where it cut off the power for high voltage (130V I think). It does display error codes indicating the reason for the cut off.
 
I've had my Progressive portable EMS shut down my camper on a few occasions over the years. Every time it shut down, it was due to a bad breaker at the shore power pole, (OR) it would not even turn the camper on because of a broken ground.

Like stated above, when it's hot outside, the demand changes. THAT's when it's very important to have an EMS working.
 
We were in Nashville,TN last July (2024) when our Southwire EMS cut power to our rig twice in rapis succession with an overvoltage on 1 leg and an undervoltage on the other. Turns iut that a transformer at the RV park blew causing these conditions. EMS prevented the voltage spike from reaching our rig and causing damage. Worth every penny.
 
I also have the Southwire EMS and was just recently impressed with it's accuracy. I have a full 50 amp hookup for my Monty at my home and stays plugged in while parked because of the residential fridge and to keep batteries charged. My house is the only one on my transformer because of distance. I have a surge monitoring system in my home and the voltage remains extremely consistent. On May 7 I got a notification that the voltage had spiked to 132.8 volts and apparently stayed there for 12 minutes. I hadn't been in the Monty for several days and when I went in yesterday, I saw the microwave clock flashing like the power had been off. Obviously, the Southwire had detected the surge and cycled off. The 132.8 volts is only 0.8 volts above the +10% allowable tolerance; that's extremely accurate!
 
We’re no longer at the park where I started this thread. The issue didn’t get fixed while we were there, even though I reported it. The EMS cut power many times during our stay. My readout was showing 135v on one leg. Power was cut at that time but the readout was still reporting. It never gave an error code, just cut the power. I have a hard wired Progressive EMS.

The pedestal only had 50a and 20a outlets. I tried the 20a and it was still 133v. I was able to run a cord to the neighbor’s pedestal for 20a and it worked just fine. Fortunately it wasn’t very warm out so didn’t need the AC.

I left a caution note on the pedestal for the next person when we left.
 

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