Focus on “Stray Voltage.” What is it and why should you care?

Focus on Stray Voltage
I’m declaring July official Hot-Skin/Stray Voltage month. For those of you who don’t know, an RV Hot-Skin occurs when the ground wire on an RV’s shore power feed is interrupted somehow. That allows even normal leakage currents inside of an RV to create a Stray Voltage on the entire RV, including its “skin,” chassis, wheels, hitch and tow vehicle. And this Stray Voltage can vary from a low-current version which only gives you a tingle, to a high-current version which will not only knock you down on the ground, it can kill you. 

But first, I’m going to rename “Hot-Skin” to “Stray Voltage,” and here’s why …
I’ve never really liked the term “hot-skin” because it wasn’t descriptive of what’s actually occurring. But I’ve used the term myself countless times because that was the accepted term used by the RV industry and one that you would recognize. However, outside of the RV industry nobody seems to know what we’re talking about. And now I’m going outside of the normal RV groups for technical support, with every other industry (including the power companies who distribute electricity) calling it “Stray Voltage.” So starting today I’m going to call this condition an RV Hot-Skin/Stray Voltage and eventually change it to just RV Stray Voltage. Hey, there’s even a Wikipedia entry for Stray Voltage here


Within a few minutes of posting this article we received a comment that we believe you should read. It’s from a reader who recently experienced a scary situation. “I was greasing the suspension on our trailer and when I touched one of the axles with my arm I felt a tingle,” he wrote. “I checked the frame of the trailer with my non contact electrical tester and found it to be hot. Click here to read more.


Enough buzz words.
What causes “Stray Voltage” and how do we test for it?

While countless websites may tell you an RV Hot-Skin/Stray Voltage is caused by something like a melted water heater element, they’re not really correct. While a melted water-heater element submerged in water can, in fact, be the current source that energizes and creates an RV Stray Voltage condition, if the RV’s shore power grounding system is in place it’s impossible for any voltage to show up on the chassis (or skin) of the RV. So if you find a Stray Voltage of more than 2 or 3 volts on your RV, then you’ve definitely lost your shore power safety ground – officially called the EGC or Equipment Grounding Conductor by the National Electrical Code. 

Expect more articles from me on this topic later, but by far the easiest and safest way to test for an RV Hot-Skin/Stray Voltage is by using a Non Contact Voltage Tester (NCVT). I originally developed and promoted this test protocol nearly 10 years ago, and every manufacturer thought I was crazy until they tried it for themselves. The biggest advantage is that this is a very safe proximity test, which means you don’t even have to actually touch the RV to check it for a stray voltage. If you turn on your NCVT and get it to within a few inches of a large energized surface, then it’s going to beep and blink like crazy. Many times it will start beeping at you from 2 feet or more away from something as large an RV with a Hot-Skin/Stray Voltage. And that beeping tells you the RV chassis (and skin) has up to 120 volts of stray voltage potential that can be life threatening. Here’s my article on NCVT test procedure for shore power hookup I wrote last month, as well as a quick video on how this works on a nano-sized RV. I’m also creating a new video on this NCVT/Stray Voltage procedure for my next RV Electricity newsletter due out the last Sunday of July, so make sure you sign up for a free email reminder here

Why is this important to you?
In a few words, it can save your life and the lives of your family!

Yes, there it is. Electricity is a great and powerful force, and modern society couldn’t function without it. However, taken for granted and handled carelessly it can become life threatening. But by simply performing a NCVT check for a Hot-Skin/Stray Voltage on the campground pedestal BEFORE you tie into shore power, and on your RV itself AFTER plugging in your shore power cordset, you’ll find nearly all RV Stray Voltage situations BEFORE they can shock you. 

Why is this important to Chuck and me?
I get emails and comments like the one below nearly every week, but this one in particular sums up why editor Chuck Woodbury and I continue to publish about this dangerous condition with very little support from the industry.   

You guys ARE saving lives by educating us RVers about possible electrical issues at campground hookups! And you potentially saved my bacon last week!

Iplugged into a 30-amp pedestal at the Munising, MI KOA. Everything seemed fine…but was I mistaken. After I was all plugged in and having the RV all leveled and such, it dawned on me to get out my Non-Contact Voltage Tester. As I placed it on my RV’s door it lit up like a Christmas Tree! Out of the 10 different times I had been connected at various campgrounds, this was the first time I had ever gotten a “hot skin” reading.

So, I proceed to check the metal steps and metal frame around the door and as you might have guessed…it was “hot” as well. I then went to the pedestal and everywhere I placed my NCVT it indicated that the entire pedestal was hot.

I immediately notified the campground management and they discovered some kind of short/defect in the pedestal's wiring. Potential disaster averted. And I looked super-smart in my wife's and kids' eyes. A rare occurrence indeed!

Thank you for this great service you provide weekly to all of us RVers. I will be supporting you monetarily from this point on. I feel kind of sheepish (cheap!) about not doing so sooner.

All the best! And keep up the EXCELLENT work! - Stephen Wickland

stray voltage patrolThanks Stephen. And stay tuned over the next few weeks for more exciting news on this topic. Chuck Woodbury and I are teaming up with a major manufacturer to invite you and any of our other readers to join our Stray Voltage Patrol. You’ll help us identify and create a national database of RV park campsite pedestals with substandard wiring that can cause a Hot-Skin/Stray Voltage on your RV. There are plenty out there that even the park owners do not know about. So we’ll ask you to help us help save other RVers from electric shock injury and even electrocution. And you’ll learn even more on how to test your RV for wiring problems that can create this condition.  

Well, that’s it for this week. See you next time. 

In the meantime, 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.

 

Related

6 Thoughts to “Focus on “Stray Voltage.” What is it and why should you care?”

  1. Robert E Staples

    Hi Mike,
    Thanks so much for your informative articles. I used to think I was pretty well versed on basic electricity until I started following you. I have learned so much since then!
    I at least realized the first upgrade I should do to my motorhome 5 years ago was to install a Surge Guard 34560. This unit has saved me from faulty pedestals twice now. Just two weeks ago I connected to a pedestal and everything was fine at first, but after about an hour the Surge Guard disconnected me from the pedestal. It reconnected after the timer ran out. That happened several times during the next few days. My vintage Surge Guard does not report why it disconnects and when I checked the pedestal with my VOM everything looked good. When I reported it to the owner, they said they knew about it and were working on it. Other campers had reported a high voltage condition. The power company had installed a recorder to help them. But then, the problem mysteriously stopped. I stayed connected without problem for several days.
    As you can imagine, since nothing was fixed the problem came back again. This time I checked the pedestal and measured 133 VAC. By the time the owner came out and checked, it was back to 122VAC. But, they determined that only one row of pedestals was affected, so they moved me to an unaffected row.
    Can you explain how a high voltage condition like this occurs?
    Thanks again for everything you do,
    Bob S

    1. Mike Sokol

      There are taps on the power company transformers that allow their electricians to adjust the voltage up and down a bit. But that probably doesn’t explain the voltage going up and down by itself. However, a neutral opening up on a 3-phase feed can do all sorts of crazy things the the secondary transformer voltage. Also, were you on a 50-amp circuit or a 30-amp circuit? If it’s a 30-amp pedestal, than a dirty neutral connection could explain everything. The Surge Guard you list is a 50-amp model, but maybe you were connected via a 30-amp adapter. Let me know and I’ll think about it some more.

  2. Nick Houser

    Hello Mike great topic. My most recent voltage converter is protected only from shot circuit, over current, and reverse battery connection. NOT over voltage , open ground. or any of the other faults leading to “Hot Skin condition” etc. What do you suggest I add to my rig to protect it more completely.
    The “No Shock zone is a great blog please keep up the good work. Nick in British Columbia.

    1. Mike Sokol

      There will be lots more articles on this topic shortly. I’ll publish more simple ones in RVtravel.com (here) and more complex “master” versions on RVelectricity.com.

  3. Richard Iddins

    Dear Mike,
    We just left a park in Alberta Canada. Where this morning when I was greasing the suspension on our trailer and when I touched one of the axles with my arm I felt a tingle. I checked the frame of the trailer with my non contact electrical tester and found it to be hot. I then checked the electrical pedestal and found it to be hot also. I then, with my volt meter stuck the black probe into the ground (Dirt) and the red lead to a screw on the pedestal. And found there to be 40 volts. I disconnected the camper and rechecked and found the same voltage. I then checked other pedestals in the park and found all of them to show voltage to ground. (Metal pedestal to ground)
    The camper next to us was a metal skinned unit that was also showing hot. I checked from the skin of the unit to ground and found the same 40 volts.

    When I notified the camp ground they were receptive and called an electrician who was there within the hour and after checking he called in the local electric provider who also sent in one of their guys.

    Before leaving the Camp ground I requested a refund for the night and they stated that they do not give refunds.

    The question I have is why would my EMS system not have shut down and given a code to tell me that we had the condition?

    Also I us the yellow plug in testers that have the 2 yellow and 1 red lights that will look for Open ground, open neutral, open hot, Hot/ground reverse, hot/ new. Reverse and correct. This tester did not show a fault either.

    Please let me know your thoughts.

    1. Mike Sokol

      While EMS systems and 3-light testers can find maybe 99% of all hot-skin stray voltage, there’s a really big miswiring condition I’ve named a Reverse Polarity Bootleg Ground (RPBG) that can’t be detected by any current surge protector technology, nor can it be disconnected from the hot ground condition. Interestingly, when I first discovered this effect none of the test gear manufacturers knew about it, or that their test gear couldn’t find it. See my initial article on it here.
      http://www.ecmweb.com/contractor/failures-outlet-testing-exposed

Comments are closed.