Tuesday, June 6, 2023


How often does RV hot-skin wiring occur?


Dear Mike,
Regarding the three essential testers (Digital Multi-Meter, Non-Contact Voltage Tester, and Circuit Analyzer) mentioned in the video from Gary Bunzer in the RV Travel newsletter recently (Three electrical testing devices all RV owners should have in their tool kit), do you have statistics (even educated guesses) on how often hot-skin wiring is actually occurring? How about the harder-to-detect Reverse Polarity Bootleg Ground? Thanks. —Wolfe

Dear Wolfe,
That’s a great question, but one that’s very hard to answer. I’ve run a few surveys on this topic, plus there are some anecdotal examples I can provide. My first survey was run here on RVtravel.com and we found from a thousand readers that 21% of them had been shocked sometime by an RV. If there are 11 million RVers in the US, that suggests maybe two million of them have felt a shock. So let’s drop this down to 10% of these shocks coming from a unique grounding failure. That’s still 200,000 potential failure points in the USA alone. Out of this how many were campground outlet failures, how many were extension cord failures, and how many were RV internal wiring failures? I just don’t know, except for the fact that I seem to get equal numbers of these questions in my email box every week.

So how many times were hot-skin voltages caused by RPBG (Reverse Polarity Bootleg Ground) miswiring? Well, that’s even harder to answer since most of the time this condition goes undiagnosed as the cause of a hot-skin voltage.

I still get a few emails every week from electricians and inspectors who thank me for bringing this condition to their attention and explaining how it happens. Remember, I not only had to discover this problem, but I named it as well. See this article where I introduced the concept to the electrical industry. And I see RPBG miswiring at least a few times a year in churches where I teach my live-sound mixing seminars. I’ve explained the concept of RPBG dangers to the pro-sound industry on ProSoundWeb.com, and where I’m now the moderator of their AC Power & Grounding forum.

So what does this mean to you as an RVer? Well, even if one in a thousand outlets you plug into has an open ground or RPBG wiring condition, and you camp maybe 50 times a year (once a week), you might never encounter one in your lifetime. However, if you’re unlucky enough to plug into an outlet with a miswired ground, then you and your family could be in serious danger. I do know the electrical industry says there are around 1,000 deaths by electrocution per year in the USA alone. How many are workers and how many are RVers? Again, there’s no good data on this since hospitals don’t often publish the cause of death. But isn’t it worth 10 seconds of your time to check your RV with a a Non-Contact Voltage Tester for a hot-skin voltage every time you plug into shore power?

That’s my 2 cents. An educated guess, but a guess it is.

Let’s play safe out there…. —Mike Sokol

Editor: Here are links to Amazon for the three essential testers (by category) mentioned in the video (Hint: check out the best-sellers if you’re looking to buy):
Digital Multi-Meter, Non-Contact Voltage Tester, Circuit Analyzer

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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6 years ago

Awesome response Mike! I knew you would be the one to ask for an *educated* statistical guess.

I built a simple 6 terminal device (installed interrupting 30A shore cord) that monitors for over/under voltage, over amperage, and the “3-light tester” polarities, and then only closes relays to power the coach while everything is good (piezo buzzer if failed). I attempted RPBG detection (essentially hacking a NC tester’s output), but don’t think it’s possible without a reference ground(?). Being lazy, i just plug in normally, it auto-analyzes, then alarms or energizes.

In five years, I’ve never hit a reverse polarity (just lucky?), but plenty of bad voltages (and my own tendency to overdraw 30A by turning everything on at once). My gizmo lives in a project box, but I was thinking if there was a demand, i could develop it into a commercial product similar to GFCI surge protectors (i know some do voltage or amperage, but i haven’t seen one address polarity yet). Thoughts?

6 years ago
Reply to  Wolfe

I stand educated/corrected… Surgegard apparently DOES make a voltage and reverse polarity cutoff functioning almost EXACTLY like my DIY box… I have a surgeguard branded surge protector but it doesnt seem to have those functions – only surge. :S

RV Staff
6 years ago
Reply to  Wolfe

Thanks for the update, Wolfe. Good information. And I like your statement, “I stand educated/corrected.” Haven’t heard that one before, but I like it. 😀 —Diane at RVtravel.com

6 years ago

I stayed at a campground this January with reversed polarity and the outlets were grounded to the box and not separately wired to the dedicated ground wire. The electrical box with 50, 30 and 20 amp outlets came like that from the factory. The electrician who installed it just hooked up the power to the box. Never checked for a problem. I don’t know if grounding like that is up to code but he definitely should have detected the reversed polarity with a quick meter check.

6 years ago

Managing several parks I have seen this multiple times. I have had supposed GFI strips,converters,and bad elements in water heaters cause this. In most cases the RV’er had no idea they were the cause. This can happen in older rigs, not so well maintained rigs as well as new ones. I always explain to the RV’ers that use the GFI strips if they are so great why dosent the industry build them into the rigs. I do not excuse bad wiring in some parks and so called know everything maintenance guys. But I personally have only found this to be the case in 1 park.

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