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Old 06-29-2015, 08:51 PM   #21
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I learned something new, Thank you Mike, and won't perpetuate the myth.
You're very welcome. And don't think you're the only one that's passed on misinformation about electricity. I have the advantage of both mechanical and electrical engineering degrees as well as having my master electrician license since 1978. Plus I've been an electrical troubleshooter for industrial power and large sound systems for decades, which gets REALLY interesting.

But the thing I'm most proud of is being a teacher and technical writer. I take that responsibility very seriously, and I'm always careful to double-check everything I write about on a forum or teach in the classroom. In fact, my college students have a standing order to attempt to debunk anything I show or discuss in class. We set up demonstrations all the time to prove or disprove what's accepted as common knowledge, all of which makes me a better engineer and teacher. And I'm always glad to be proven wrong in my assumptions, since that means I'm continuing to learn, which is a great thing.

So as long as you're continuing to learn, you're still living. Once you think you know everything there is to know, that's when you're totally wrong.

Let's play safe out there. And feel free to ask me any questions about electricity and electrical safety.

Mike Sokol
www.NoShockZone.org
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Old 06-30-2015, 07:54 AM   #22
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I never meant to imply he should flip his cables without troubleshooting, but you're right... I'm not a licensed electrician and will refrain from making any additional comments with regard to RV power systems in the future.

yarome, don't take it the wrong way, I didn't mean anything derogatory. I had two years of school for electricity, um, 35 years ago and grew up wiring houses and I still was a bit intrigued when I started reading about this "reverse polarity" on AC wiring related to RVs.

I don't consider my self an electrician and my knowledge is limited but I do know that when you talk about polarity related to AC you usually think of AC cycles not reverse wiring. I have a friend who is an electrical engineer so I asked him about this and his thought were the same as mine. So my guess is this term is being used in the RV industry for lack of a better term. I could be wrong and have been before

Furthermore, I would not have ever expected this to been an issue in a campground but I guess it is. I have been camping for 40 years as has my buddy and neither of us have ever heard of this issue until I joined this forum.

The whole electricity thing can be a bit scary and loaded with liability. So maybe we both should just grab a cold one and relax under the awning somewhere. Cheers

PS: I thought Mike's write up was great and should be of help in the future.
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Old 06-30-2015, 08:54 AM   #23
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I do know that when you talk about polarity related to AC you usually think of AC cycles not reverse wiring. I have a friend who is an electrical engineer so I asked him about this and his thought were the same as mine. So my guess is this term is being used in the RV industry for lack of a better term.
You are correct. I hate the word "polarity" when referring to AC power. That's because an AC outlet actually reverses its own polarity 120 times per second for 60 Hz power in the US (it's 50 Hz in much of Europe). But the RV industry uses Reversed Polarity to describe what's actually reversed Hot and Neutral wiring. I think that's because in the 40's and 50's there was something called a non-grounded "polarized plug" on radios and home appliances. And those early appliances lacked input transformers, which bonded the incoming neutral wire directly to the chassis. So if the "polarized plug" was flipped, reversing its "polarity", then the radio chassis was connected directly to the hot wire, which could be lethal.

That's why all modern appliances have some sort of power transformer to isolate their own chassis from the power line. The exception is double insulated power tools and things like hair dryers with GFCI plugs. So with all modern appliances and RVs, it really doesn't matter if the hot and neutral wires are reversed. There are tons of old wives tales that swapped H-N lines somehow burns up on-off switches, or causes an appliance to use more electricity, or hum, or whatever. But that's all incorrect information. The REAL danger is that troubleshooting a system with the neutral wire energized to 120-volts can be deadly to the technician doing the testing.

So why should you care if your RV outlet shows reversed polarity? Well, if you have a second miswiring condition in your RV, specifically an internal Ground-Neutral Bond, it's possible for a reversed H-N outlet to create a hot skin condition. Also, it shows that whoever wired the electrical outlet doesn't know what they're doing and could have made other mistakes. So don't accept reversed Hot-Neutral outlets on a pedestal since it's an obvious mistake that should be corrected.

One of the things I've pitched to the RVIA and various inspection agencies is the idea of a testing RV pedestals for proper grounding and "polarity" yearly or maybe every other year. And I think they should also be retested anytime there's been a repair done on a pedestal. But it's slow going since nobody wants to spend money, even if it is for safety.

BTW: I don't like the term "RV hot-skin" either, since it's really a hot-chassis condition that also spreads to the RV "skin". So a hot-skin condition creates voltage not only on the "skin", but also on the RV's wheels, trailer hitch, the tow vehicle, door handles, metal steps, etc... That's why an RV hot skin is so dangerous.

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PS: I thought Mike's write up was great and should be of help in the future.
Thanks very much.

Mike Sokol
No Shock Zone
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Old 06-30-2015, 09:17 AM   #24
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A side note. Don't assume that since you stayed at your favorite site several weeks ago and the pedestal was wired correctly that it will be so when you go back a few weeks later. The outlets and breakers in pedestals take a real beating and have to be replaced much more often than your outlets and breakers at home and may have been replaced since last visit. If it was an emergency repair ( busy wknd or late at night) it may have been done by someone under qualified.

Site Mod: Maybe Mike's write up should be a sticky.
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Old 06-30-2015, 03:40 PM   #25
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A side note. Don't assume that since you stayed at your favorite site several weeks ago and the pedestal was wired correctly that it will be so when you go back a few weeks later.
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Old 08-04-2015, 11:22 AM   #26
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I did actually find the problem. It was a bad extension cord from the house to the trailer power cord. When I went to unplug the trailer, I noticed it was all melted out. Replaced the cord and the problem is gone!
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Old 08-04-2015, 11:40 AM   #27
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I did actually find the problem. It was a bad extension cord from the house to the trailer power cord. When I went to unplug the trailer, I noticed it was all melted out. Replaced the cord and the problem is gone!
Excellent. Thanks for letting everyone know, as it may help others with similar problems in the future.

Sounds like maybe too much current for the size/length of extension cord you might have been using. Glad you got it all fixed now. We all like a happy ending.
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Old 08-04-2015, 12:11 PM   #28
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I did actually find the problem. It was a bad extension cord from the house to the trailer power cord. When I went to unplug the trailer, I noticed it was all melted out. Replaced the cord and the problem is gone!
Every week I get several emails about RVs with hot-skin conditions, and the vast majority of times it's caused by a extension cord plug or dog-bone/pig-tail adapter. See my article on hot-skin conditions at RV Electrical Safety: Part IV ‚€“ Hot Skin | No~Shock~Zone and videos at and
The takeaway is to treat EVERY shock from an RV or appliance as potentially life threatening. A properly grounded RV will never have more than a few volts (max of maybe 2 or 3 volts) between its chassis and earth ground. If it has more than that, then the EGC Safety Ground has lost continuity somewhere on its way to the service panel's G-N bonding point. Find it and fix it immediately as the next shock could kill you or a loved one.

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Old 08-04-2015, 12:27 PM   #29
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I've done electrical/communications work for 43 years... and have a professional title in the field... Well done Mike! This is the BEST information about any subject I've seen on any RV forum.

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Old 08-04-2015, 01:20 PM   #30
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I've done electrical/communications work for 43 years... and have a professional title in the field... Well done Mike! This is the BEST information about any subject I've seen on any RV forum.

Thanks very much. I've been trying to get Forest River to support a tour of No~Shock~Zone Clinics at campgrounds and dealerships around the country, but still no luck. If any of you have connections at FR, please tell them about this program. I have a bunch of table-top and full-size demonstrations on electrical safety that are really educational.
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