Tuesday, September 27, 2022


RV Electricity – Low Voltage Report

Dear Readers,
Since the Stray Voltage Patrol is already generating some interesting reports, I’m going to use one of them to discuss the problem of low voltage in campgrounds, especially state owned and operated parks. Here’s what part of an SVP report looks like: 

What did you discover? Pedestal voltage measured too low (below 104 volts)

Describe what you discovered:  Voltage 117 with about 10% of sites filled, but got down to 93 Volts with 85% of sites filled. Very time-of-day dependent as campers turned on AC or cooking loads, but voltage in the 90s is terrible sag!

Number of campsites tested: 4

Name of campground: Willow Bay Recreation Area

Campground owner name: PA State Park

What are the basics? Well, it’s simple. The electrical distribution grid powering this campground wasn’t designed with enough capacity to provide a full campground with stable electrical power. There’s a variety of specific design flaws that could be suspect, but I’m guessing it might be the main power company line transformers being of insufficient size to power the entire campground when everyone is running their air conditioners at the same time. While the power company can, in fact, change the taps on the incoming transformers to boost the voltage a bit, that 117 volts is actually very close to the NEC (National Electrical Code) design specs. In fact, I’ll bet that if you turned off EVERYTHING in the park, the voltage would bump up to 120 volts. 

So is this bad? In a word, yes. Now, it’s not likely to cause a hot-skin/stray-voltage, nor is it likely to start a fire in your RV. However, it’s very likely to cause many RV air conditioners to either not start or even burn out. Residential refrigerators in the RVs will also have the same sort of issues. Compressor motors tend to be very amperage hungry during startup, and rely on a stable 120-volt power source to get up to speed quickly. I’ve often said that anything below 100 volts can be damaging, and here we have an example of 93 volts. So, use at your own risk since I don’t think the state park is going to pay for your new air conditioner or refrigerator. 

Is there a quick fix? Now the inevitable questions about Hughes AutoFormers will start coming in. And while an auto-boost transformer could increase the voltage at a single campsite, it will be stealing even more voltage from the campsites around it. Don’t believe the marketing hype on the Hughes website. A booster transformer can’t restore full wattage (power) to a campsite. It can only restore full voltage by essentially stealing it from other campsite pedestals in the area. That’s why the 2020 version of the National Electrical Code will likely prohibit booster transformers in campgrounds. 

Why does this happen? It’s also possible that the branch circuits in the park weren’t designed with heavy enough electric wiring for the length of run between campsites. For example, if you run a 10-gauge/30-amp extension cord 25 feet you might experience 2 volts of drop under full load. But run a 10-gauge branch circuit 200 feet (8 times as far), and the voltage drop under full load will be increased to perhaps 8 x 2 volts = 16 volts. Starting with 120 volts at the distribution point, we can subtract that 16-volt drop and end up with only 104 volts at the pedestal. And that’s just for ONE campsite that’s running their air conditioner. Multiply that by dozens or even hundreds of RV air conditioners at a campground, and you’ll see just how and why 93 volts is possible. Yikes!

Is this an expensive fix? Well, it sounds like either the incoming power company transformers are out of capacity, so the power company will need to upgrade to larger KVA units, or the underground wiring is too small for the lengths of run they have to do, so the old wiring will need to be dug up and rerun with heavier gauge copper wire. Both options are expensive, which will have to be passed on to the consumer, either by taxes and increased registration fees for the state-run parks, or increased day rates for privately owned campgrounds. Running new electrical distribution isn’t cheap, but it’s probably the only way many parks like this can get their power up to acceptable levels.   

Please answer in the comment section below about any state parks or private campgrounds you’ve found that have low voltage. It appears to be a major problem in many campgrounds. 

Let’s play safe out there….


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




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Richard Wildhirt
11 months ago

Fascinating. This is almost exactly what the RV tech we used in Utah said to us. We bought the 50 amp auto former from Hughes (his recommendation after our Hughes dog bone died) and started using it yesterday. The thing weighs a ton, but it is working well. It’ll be interesting to see how it does in some of the older RV parks we plan to stay at.

Carrie Young
2 years ago

We are experiencing low voltage at an older private park . We believe both power company and park are inadequate. But we like it here. Hughes Autoformer booster should arrive tomorrow. Hope it works..

David Schlagel
2 years ago

The Birdsong RV park in TN has an awful electrical problem. The main panel we saw opened had multiple wires attached to the same power lugs. We had our Hardwired Progressive system fried there. Park wouldn’t offer to pay for even 1/2 replacement

James Orcutt
2 years ago

I am currently dealing with a park in southern California and been having low voltage issues. The owner sent an electrician out yesterday but it was not during heavy use and found no issues. However last night and again this morning my Hughes Power watchdog shut off the power several times but I doubt the electrician would be authorized to come out when I am actually experiencing issues.

2 years ago

Does anyone know y my fuse to my r.v battery keeps blowing and how to fix the problem or what to look for or test

George Daunis
3 years ago

Mike, I was at a park in Mass this Fourth of July during a heat wave in the high 90’s. Power was typically running from high 90 volts to 105 volts during the days with all the AC’s running full blast. The campground owner passed out a flyer instructing people to switch their refers and water heaters to propane if possible. Also to raise the thermostat a couple of degrees higher. All good ideas, but my question is why could you not just start your generator and run off the gen until power recovers as night approaches. If I did this, would it be necessary to unplug the RV at the pedestal or just leave it plugged in while running the Gen.
If the campground would allow this it would remove a lot of the big power hungry Big Rigs and allow the Campground voltage to recover.

Dennis Foley
3 years ago

Soo Locks Campground in Sault St Marie, the voltage went low enough at night to have my EMS shut off the power quite a few times, then turn it right back on. The voltage hovered around 104. It’s cold there so I assume a lot of people were running heaters, but the park was not full. Nice spot and people by the way!

4 years ago

Mitchell RV Resort, Perrin Texas. Site 63, reversed polarity on 30 amp plug detected by our Progressive Industries EMS. Had been previously reported according to park management but had not been corrected as of 9/6/18.

Cynthia Steiner
4 years ago

We had to leave our 4 night stay at Yosemite after only one night due to the fire this summer. It forced us to find another campground for 3 nights before we got to the next reserved campground spot. We were on 7 week trip from Indiana to California and back. We got a spot at Club Royal Oak in Kingsburg, CA. Our inside volt meter showed we were only pulling in 94 volts, but the campground maintenance man insisted he checked the electric hook up and it was fine. Our air shut off and temps were in low 100’s. We had our 3 cats and small dog in our 25 ft. Travel trailer. Couldn’t keep air on and told management we we’re leaving. Instead they moved us to another site at 7:00 pm. We had air all night and left at 11 am next day for Kings Canyon National Park. Got back at 4:30 in pm and no air in trailer. Dog panting and cats listless. Put dog in sink under cold water and crated cats and put in truck with air on. We told management we we’re leaving. They would not refund last 2nights we didn’t use ($120). They said no one else complained, but as we were leaving 2 of our neighbors said they didn’t have air in afternoons, but they just stay outside under their tents or play in the Kings River where the campground was located. They had not complained. We never had a bit of trouble with our air going off at any of the 21 other campgrounds we stayed in those 7 weeks. When we checked in on a Tuesday, we were told they had 2400 plus people in the campground over the weekend and most we’re still there and no room available beginning on Friday. Did they overbook, have poor hookup or was it power company problem? Don’t know. But I think they knew they had a problem but would not acknowledge. Manager finally offered to comp us for 2 nights at some future date, but we were on our way back to Indiana and did not want to ever come back to this campground as we put our pets in jeopardy and could have destroyed our air conditioning unit too.

William Maginot
4 years ago

We have been on the road since July 6th and have stayed at 7 different campgrounds (including the FMCA rally in Gillette) and all but one had good power and no faults. The campground in Ruidoso, NM (Riverside RV Park) had low voltage. I tried to work with them, but nothing got accomplished. The L1 voltage varied from 118v to 102v. The L2 voltage remained fairly constant, 120v to 118v. The row we were on had a mixture of 30a & 50a. I had the opportunity to look at the breaker boxes when one of the sites lost power. I was shocked (but not surprised) at what I saw. Some of the sites were fed with 10ga wire, some with 8ga, and one had 12ga feeding it. I point this out to the owner and he did not seem concerned. He professed he knew something about electricity, but did not even know how to read my meter. Needless to say, I left him to his “problem” solving and kept a close watch on the power at my site. Fortunately we did not need to run the AC while we were there. We won’t be back to this campground.

Mike Sokol
4 years ago

I’ve seen a number of campgrounds that didn’t alternate the 30-amp outlet between the two legs on each pedestal. What that does is allows a bunch of 30-amp RVs to pull down one side of the 50-amp outlets, just as you experienced. The fix is pretty simple, alternate the 30-amp connection in each pedestal on that branch circuit between L1 and L2. That will balance the current load from 30-amp RVs between the two hot legs. Better for everyone that way. Unfortunately, not a lot of casual campground technicians or even licensed electricians understand this simple load balancing trick.

Mike Sokol
4 years ago

“He professed he knew something about electricity, but did not even know how to read my meter.”

Yeah, I don’t think so. Just like a DJ always carries their own headphones, any electrical maintenance tech should carry their own meter, and be able to figure most any other meter in a pinch. Before you can understand or work on anything electrical, you have to understand how to meter it.

I’m currently slammed with getting all my other RVelectricity articles and videos done and published, but very soon I’ll begin shooting videos on multi-meter operation. I think it’s a very important topic and something I’ve been using for over 50 years. Gosh, has it been that long….?

4 years ago

I’ve had my EMS shut down our camper on a couple of visits to the Kentucky Horse Park, Lexington KY. 30 amp circuit was experiencing problems. First time, I visited the office and attendant was selling a dog bone to person ahead of me, saying they could return it when they left the park. Said the 50 amp circuit was OK. I went back and put in my 50-30 dog bone. No further issues.

4 years ago
Reply to  Al

Had similar problem there on site 174 two yrs ago. Smoke and sparks flew when I plugged in 50 amp and flipped the breaker on. Immediately turned off and called the office. Maintenance worked on and declared OK. Turned on air and went to nearby Georgetown for supplies. Returned two hrs later and no air. Maintenance came again and replaced a breaker. Declared OK. Fired up air again but wouldn’t seem to cool down. Found rear air blowing warm. Mobile tech diagnosed a\c unit shot. Did not know enough about electrical issues to question what may have been the cause. That has since changed as I now follow several online forums and have educated myself to some degree on how to protect our rig from potential problems (low voltage, hot skin, etc). I am convinced my a\c unit failure was due to the problem that day. Due to my ignorance I did not report or file a complaint with the park. From several other posts it does not appear it would have mattered. The park was at max capacity that week due to a popular music festival going on. I’m sure this was a contributing factor. Good news was my extended warranty covered the $1100+ cost for replacement but I would just as soon not had the aggravation. Thanks to all for the helpful posts relating to this type of problem.

Nancy Michaels
4 years ago

Mike, back in July we parked in an otherwise unoccupied hook up area in Thedford, NE at the Arrowhead Motel. Was just going to be a short overnight stay. After plugging into a 50 amp set up, our air conditioner did not work (95 degrees out) and then smoke rolled out of the open compartment where our DVR and dish receiver stay. We pulled the TV component out immediately and unplugged from the main hook up. We later found that this mis-wiring had fried our electronic components – dish receiver, convection microwave and central vac. Expensive and time consuming repairs since none of these items are still being sold!!
We have since ordered a surge protector from Progressive!

Terry O'Keefe
4 years ago

Just a comment about wire size loading and the age of a given campground,or even house.
As an electric co. troubleman,I have seen all kinds of voltage problems.
What people have to remember,is that in the no so distant past,there were homes with 15 or 20 amp services! Then they went to 30,60,100,150,now 200 amp services!
Used to be that if you had a tv in your camper you were the odd one in the group,now my class A has 4,and electric hot water,microwave residential refrigerator and such.Campgrounds are updating as they can afford to, but are under no obligation to do so,other that to stay in business when the power finally all goes bad.
I guess my point is, there is a good chance to see older parks,under wired and under fed from the utility company if there isn’t major outcry from their customers. Maybe the stray voltage patrol will help change that, but rest assured,we will need to help pay for it…..I borrowed Chucks soapbox….

Mike Sokol
4 years ago
Reply to  Terry O'Keefe

It will likely cost even a small, older campground a few hundred thousand dollars to upgrade the wiring to accommodate modern, power hungry RVs. And as you and I both noted, SOMEBODY’s got to pay for it. The campground owners won’t do it themselves unless they can charge an increased rate. And unless this is a state park there’s no tax dollars to supplement the upgrade. If it IS a state park, then the limited government funds are spread out over other infrastructure needs such as roads. There’s just no simple solutions, so the best we can do is figure out how to make-do with less amperage. Unfortunately, the big amp-draw appliances are the ones we need the most. So unless we’re willing to give up our air conditioners and microwave ovens, there’s little chance of reducing shore power needs by much.

RV Staff(@rvstaff)
4 years ago
Reply to  Terry O'Keefe

That’s fine to borrow Chuck’s soapbox, Terry, just so long as you remember to give it back. I don’t know what Chuck would do without it! (His head might explode!) 😉 –Diane at RVtravel.com

4 years ago

We had the opposite happen on labor day weekend. We stayed at Newberry Campground in the U.P. of Michigan and our Progressive EMS shut off 3 times during a 2 night stay due to HIGH voltage.

Curtis King
4 years ago
Reply to  Jeremy

For Jeremy…….was that the old KOA in Newberry or Kritters? I have reservations for Kritters end of September. Thanks

4 years ago
Reply to  Curtis King

Curtis, it was the old KOA.

Mike Sokol
4 years ago
Reply to  Jeremy

I’ve seen this voltage rise caused by an undersized neutral on the incoming feed from the power company. One of the reasons for this is that 3-phase power distribution often plans for a certain amount of balanced current between the 3 phases. And many 3-phase systems for factories primarily fed 3-phase electric motors which don’t need a neutral at all. So the designers of many 3-phase power distribution systems could get away with smaller neutrals, thus saving some money on the wiring. However, RVs are hooked up single-phase, so if there’s a huge power load on one or two of the legs (phases), then the voltage on a lightly loaded 3rd leg can easily rise by 10 volts or more. Been there, seen it with my own eyes (and meters).

4 years ago

“Inevitable” is right… I was going to ask about line conditioners as a solution (in general; I haven’t used an Autoformer specifically).

I wonder about the “stealing” characterization and NEC advisory, though, because I would think you’re still limited by the pedestal’s breaker amperage, no? If line conditioning works like a variable tap transformer, you could turn 80V@30A input into 120V@20A out, but the breaker would pop if you tried to draw more wattage out at 120V (?). With Ohm’s Law, you’re using your (now) 2400W “share” at 120V without burning out your equipment, but you still can’t pull “extra” power (W) from neighbors compared to if you were browning yourself out.

Mike Sokol
4 years ago
Reply to  Wolfe

To clarify my point about booster transformers stealing voltage from other campsites, what happens is the transformer will trade volts for amperes. That is, if the voltage at the pedestal is 20% down, it will draw additional amperage from the pedestal to make up that voltage. And since that amperage draw is downstream of the pedestal circuit breaker, you will never get full wattage. So instead of 30 amps available at 120 volts (3,600 watts) from a properly sized distribution system, you might only have 24 amps at 120 volts (2,880 watts) available. Since 30 amp shore power is often highly stressed by modern RVs, you’ll be running that pedestal closer to max amperage draw more of the time. What that does for other pedestals in that campground loop is increase the overall voltage drop even more. The point is that booster transformers are a technology that don’t do what they advertise (restore full power), while increasing sagging voltage problems at nearby campsites. The only real solution is to install heavier wiring and larger power company transformers in the campgrounds.

2 years ago
Reply to  Wolfe

A fuse or circuit breaker operates on “Watts” Volts x Amps. Not just simple amperes. Watts are heat. Heaters are rated in watts. Heat melts a fuse and heat trips a circuit breaker. A 30 amp, 120V circuit breaker will trip at 3,600 watts, more or less based on time and/or temperature. An autoformer allows the full 3,600 watts to be pulled through the circuit breaker or fuse. So if park power is 80V the circuit breaker will pass 45 amps before theoretically tripping. As amperage demand increases, voltage in the system decreases. Circuit breakers protect wiring, they do not regulate the fair distribution of electrical power in the RV park. Autoformer’s steal power from others as NEC states.

Mike Sokol
4 years ago

How did this pass inspection? Of course, there could not have been any kind of electrical inspection to allow this to occur. It would be interesting to find out who the AHJ (Authority Having Jurisdiction) is for the county. I’ll make a few calls next week and see if I can find out who’s in charge of this.

4 years ago

Colorado River Thousand Trails, Columbus TX along the river sites.

Old undersized aluminum wiring. After a flood they put in new 50 amp pedestals to replace the previous 30 amp pedestals- without upgrading the wiring run.

Even when sites are less than 50 percent occupied, voltage sags below 104 volts many times per day and night.

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