Saturday, June 10, 2023


RV Electricity – No~Shock~Zone by Mike Sokol – Issue 21

Issue 21 • July 28, 2019

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Read back issues of this newsletter and many other articles by Mike Sokol on Warning: There is a lot to learn here.

Welcome …

By Mike Sokol 

Welcome back to the show that never ends…

While I was going through back issues of my No~Shock~Zone articles updating and republishing my original 12-part series on RV Electricity, I discovered something really interesting. Next year will be my 10th anniversary of writing electrical articles for the RV industry. All I can say is, WOW!

Seems like only yesterday that I started Googling about hot-skin conditions and hooked up with Gary Bunzer (the RV Doctor), and he said there would be only one e-zine producer he could recommend who would be fearless enough to publish what I was writing about RV Electricity – and that was Chuck Woodbury from Yes, even when the RV industry told me I was rocking the boat and scaring everyone away from buying an RV that could “shock” them, Chuck told me “full steam ahead,” and don’t worry about any naysayers.

In fact, Chuck has been one of my biggest cheerleaders and lab rat, both at the same time. You can guess what the cheerleader part is, but the lab rat moniker may require a little explaining.

Chuck reads everything I write and gives me feedback if I’ve gone too far without explaining myself first. And that’s an important function, since I normally teach at college level and even provide consult to manufacturers on product design. The real trick is to take what’s actually a really complicated topic and boil it down to the fundamentals that anyone can understand. It’s not easy, but that’s exactly what I’ve been trying to do for the last 10 years.

Now it’s time for me to take what I’ve learned about teaching you all about electricity and turn it into more seminars and videos. Yes, I’ve dabbled in both over the last year, and they’ve been working pretty well. In fact, my RVelectricity seminars have been getting a full house in many rooms, with top attendance for an RV rally or show. And I thank you all for that. Without your questions and feedback I might as well be teaching on an island. But add comments, both in a seminar and in these articles, and I instantly know if I’m getting through to you or just spinning my wheels.

So my big project for my 10th anniversary in 2020 is to get ALL of my RVelectricity articles into one place (, and develop a simple way for readers to find everything I’ve written on dozens of topics that you might not even know the name of. For example, I had to invent the term Reverse Polarity Bootleg Ground (RPBG) when I discovered a very dangerous miswiring condition that no tester on the market could discover. And I found that a Non-Contact Voltage Tester (NCVT) would indeed discover an RV hot-skin condition down to 40 volts or so, right at the danger level where electrocution could occur. And on and on it goes.

I’m currently doing all kinds of experiments with inverters and seeing how low voltage affects air conditioners and residential refrigerators. When I say I’m having “too much fun,” I really do mean it’s a lot of fun for me to do this.

In the coming months I’ll get all the bits of this pulled together, and then I just have to put in the hundreds of hours needed to organize my articles in a way you can better utilize them. And I’ll include a test section that will allow me to see if what I’m doing works.

I’ve always felt that the failure of a student to learn is actually the failure of the teacher to teach. So please let me know if my teaching style works for you. If not, tell me and I’ll adjust. And please let me know if you’re part of any Rallies or Expos in 2020 that can host one of my RVelectricity Seminars or Master Classes. I really do love the direct feedback I get from a room with 100 or more students. Yes, that’s also too much fun!

Seriously, it really is my privilege to teach you all about electricity, and I sincerely thank each of you for taking the time to learn from me. Let’s hope the next 10 years is just as exciting for all of us as the last 10 years have been.

I hope to see you in 2020, if not later this year. In the meantime, let’s play safe out there… 

P.S. And just a quick note
that this newsletter is made possible by the voluntary pledges of the readers of We could not bring this to you without their support. If you deem what we provide to you here and at to be of special value and would like to be a part of our effort, please consider pledging a voluntary subscription. More information is here. We will include you in special emails, articles and videos exclusively for our supporters.

If you haven’t yet, be sure to join
my new Facebook group, RV Electricity.
(More than 3,000 members and counting.)

12-volt DC electrical systems

How to install a disconnect switch for 1-, 2- and 4-battery systems

Dear Mike,
I’m a paying member of because I appreciate the hard and honest work you and Chuck do. Thank you. In your newsletter #20 you talked about disconnect switches and said you would do an extended article on the subject in a few weeks. Not sure if you have or I missed a newsletter, but I’m interested in a wiring diagram of two 6-volt batteries in series and connecting a disconnect switch. I have a 2-post on-off switch. Do I disconnect the negative cable that goes from my trailer frame to my battery and connect it to one post on the switch, then take another cable, connect it to the 2nd post and run this cable to the negative post on the battery? —Mark Eddy

Dear Mark,
Ah, yes. The series/parallel battery question about where to place the disconnect switch. But before we get into the details, let me first give you all a few precautions when working around 12-volt DC power, especially when you’re moving battery terminals around.

Read more

Email me at mike (at) with your questions.

Watch Mike’s one-hour recorded webcasts 
All about portable generators. Recorded May 19, 2019
RV power pedestals: what you should know. Recorded May 10, 2019

Industry Updates

Watch an electric Ford F-150 tow more than a million pounds

Ford is trying to show its rabid pickup truck fans that EVs aren’t just for latte-sipping Tesla pilots. In an impressive demonstration of torque, an electric F-150 prototype towed 10 double-decker rail cars stuffed with 42 current-model F-150s, weighing over a million pounds (500 tons) in total. That shows promise that it could beat Ford’s current towing champ, the 2019 F-150 with a 3.5L twin-turbocharged V6, that’s rated to tow 13,200 pounds (6.6 tons).

Read the full article HERE.

Let me note that pulling a million pounds of rail cars has little to do with just how much your truck can safely tow. However, this publicity stunt demonstrates that the major truck builders are beginning to think seriously about all-electric vehicles. It’s just a matter of time before they’ll be here. —Mike

Survey Question

Have you ever experienced a burned shore power plug?

RV Electrical adapters at Amazon. Big selection, great prices.

Last month’s survey results:

Click image to enlarge.

Do you have a digital clamp meter?

This was certainly an interesting survey. It appears that 25% of you have a digital clamp meter and know how to use it. That’s great, because clamp meters are extremely useful for troubleshooting electrical problems. If you ain’t got no current, then you ain’t got nothing happening. But more than half (53%) of you don’t have one and want to learn more about them. I smell real teaching opportunity here. I’ll see if I can come up with a few cool demonstrations for you.

In the meantime, here’s one of my first videos where I demonstrate how you need to split out the hot and neutral wires in an extension cord if you’re trying to use a clamp meter to measure the load current of an appliance. Watch it HERE.


Tools and Other Devices

Tracing what’s hooked up to where

Now this is a little more than a casual tool or meter for when you’re connecting to a campground pedestal. But if you’ve ever had to troubleshoot wiring and needed to know what electrical outlet was connected to which circuit breaker, then this is the tool for you.

For less than $50, the Klein ET310 transmitter/receiver pair lets you figure it out quickly. All you need to do is plug the little transmitter end into the outlet in question, then scan the circuit breaker panel with the receiver “wand” and voila – you know which breaker is powering that outlet without resorting to flipping random breakers on and off. Plus the transmitter doubles as a 3-light outlet tester letting you know if there’s a Hot/Neutral polarity reversal, open ground, etc., as well as checking GFCI operation. And yes, the two pieces plug together so one doesn’t get lost in the shuffle. I really like this tool and think that every technician and serious DIY troubleshooter should have one. —Mike

Learn more or order at Amazon.

Last Month’s Posts

These articles are rated Moderate to understand for most RVers.

RV Electrical Safety: Part 4 – Hot-Skin Voltage. (Mike’s most important article to date.)
Better 30-amp power connectors.
Tighten those transfer switch terminals carefully.
RV Electrical Safety – Part 3 – Measuring outlets.
Generator grounding and bonding.

Last Month’s JAM (Just Ask Mike) Session posts:

These articles are rated Easy to understand for beginners.

Generator starving for fuel?
How does a 30-amp dogbone power a 50-amp RV?
Would you plug into this pedestal?
AC and DC trailer hookups.
The Name Game for 100-amp campsites.

Mike’s Featured Tips in last month’s RV Daily Tips Newsletters:

(These are not necessarily electricity related.)
Don’t forget the fuses.
Don’t swat at a wasp nest – or at least be prepared if you do.
What’s better than a carabiner? Well, an S-Biner, of course!
Cheap engine oil filler funnels.
Don’t operate without your gloves

New & interesting finds on Amazon!
See what really cool stuff Amazon is featuring today. It’s a whole lot of fun just browsing through all these great items. The selection changes every day, so check back often. You never know what you will find, which is part of the fun of visiting here. Check it out.

Q&A’s from my Facebook group:

I’m getting a lot of interesting questions on my RV Electricity Facebook Group. Here’s one with an answer that’s not obvious. Sometimes the seemingly simple things are the most complicated. 

Q: Would it be possible to combine two 15-amp circuits, on separate breakers, to generate a 30-amp input? Would you run into phase problems? —Wilson Ferguson

A: Please don’t. On a 50-amp rig you might have phase problems. On any rig one breaker will trip first grossly overloading the other’s wire and breaker. I’ll also bet it violates code. And someone may shut off one breaker thinking it’s off and get electrocuted as the other is on. —Mike Ehlert


Email me at mike (at) with your questions.

The best book on RV electricity, hands down!
Mike Sokol is America’s leading expert on RV electricity. Mike has taken his 40+ years of experience to write this book about RV electricity that nearly anyone can understand. Covers the basics of Voltage, Amperage, Wattage and Grounding, with additional chapters on RV Hot-Skin testing, GFCI operation, portable generator hookups and troubleshooting RV electrical systems. This should be essential reading for all RVers. Learn more or order

Mike’s RVelectricityTM Seminars

Knowledge is power, and I’m delighted to offer my educational RV Electricity seminars to RV shows and rallies around the country, both large and small. If you know of an RV show or rally that could use this educational content, please contact with the subject line Seminars.

Upcoming RVelectricityTM Seminars 

Always double-check the times and dates as sometimes these change at the last minute

Enumclaw Expo RV Show near Seattle, WA: Aug. 1-3. See Mike’s topics and the schedule here.

FROG (Forest River Owner’s Group): Goshen, IN: Aug. 14 (3 p.m. to 4:30 p.m.) and Aug. 15 (9 a.m. to 10:30 p.m. and 1:30 p.m. to 3:00 p.m). RVelectricityTM  Master-Class Topics – Parts I, II and III (free seminars). Here’s a link to the FROG Rally schedule. Or click on the schedules below to see them in full size.

Hershey RV Show in Hershey, PA: Sept. 11-15, 9 a.m. to 10 a.m. Understanding RV Power & Surge Protection (free seminars).

Holiday Inn Harrisburg/Grantville, PA: Sept. 14, 1 p.m. to 4 p.m./5 p.m. Advanced RV Electrical Troubleshooting. 3-hour class plus 1-hour Q&A ($125 per seat). More information and register HERE.

Camco Store at
There isn’t much you need for your RV that Camco doesn’t have. If you think we’re kidding, then click through to the Camco store on Amazon where you’ll find some of their best-selling products — all for your RV or for you to make your RVing better. Click here and you’ll feel like a kid in a candy store.

Road Signs

By Mike Sokol

Permission to fail

“Never let the fear of striking out keep you from playing the game.” ―Babe Ruth

I was reminded recently of this famous quote from perhaps the most famous home run hitter in the history of baseball, Babe Ruth. You see, my twin boys bought a house last year, and one of their new homeowner projects is finishing the basement into a man-cave.

Of course, I offered to supervise and then assisted by helping them design a complete new electrical system with a 100-amp subpanel, and 8 separate 20-amp branch circuits, each on its own switch. Yes, a lot of power for a basement, but when you start adding up video games the power requirements grow rather quickly.

Read more.

Let’s play (the game) safe out there…

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


Editor: Mike Sokol. publisher: Chuck Woodbury. Managing editor: Diane McGovern.

Everything in this newsletter is true to the best of our knowledge. But we may occasionally get something wrong.  So always double check with your own technician, electrician or other professional first before undertaking projects that could involve danger if not done properly. Tips and/or comments in this newsletter are those of the authors and may not reflect the views of

Mail us at 9792 Edmonds Way, #265, Edmonds, WA 98020.

This website utilizes some advertising services. Sometimes we are paid if you click one of those links and purchase a product or service. Regardless of this potential revenue, unless stated otherwise, we only recommend products or services we believe provide value to our readers. Amazon and the Amazon logo are trademarks of, Inc. is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to includes links to other websites. We cannot control the content and/or privacy policies of those sites. Please be aware when you leave this newsletter or any other section of to read the privacy statements of any of those websites that collect personally identifiable information. Our own privacy policy applies only to and its affiliated blogs and websites.

This newsletter is copyright 2019 by


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John T
3 years ago

An electric truck towing rail cars is meaningless. The rolling resistance of steel wheels on steel track is negligible.

Roy (not Rot ,as in the newsletter greeting)
3 years ago

The shore power pedestal experienced a surge due to work on the line ,happily my surge protector caught it with no damage to my coach!

3 years ago

THIS IS THE MAIN REASON, MIKE SOKOL and Myself are always Harping to people to invest in a Smart Surge Protector.

RV Staff
3 years ago

Ha! Sorry, Roy. I looked in the records and that was how you had typed your name when you signed up and the technology didn’t even consider that it might be a typo. I’ve fixed it, so you should now be greeted as “Roy” and not “Rot.” Sorry! 😀 —Diane at

3 years ago

I was told and I cannot divulge how I know this but stay away from electric vehicles until they get them perfected. From what I was told? They struggle to tow and can make easy prey for criminals.

Mike Ward
3 years ago

I recently added a battery cutoff switch for my RV’s house batteries. If anything, your articles have taught me to be cautious and treat electricity with a healthy respect. After doing some research and asking lots of questions I went from adding a simple battery cutoff switch to better hardware, cables and switches. Some of those changes included:

1. A marine grade, ignition rated switch because the battery tray is adjacent to the propane tank.

2. I have 300 amp hours of batteries. I opted for the 600 amp switch even though 300 amp switch was within spec. When I upgrade to Lithium I’ll likely have 400 or 500 amps or whatever the space permits.

3. Perhaps most importantly, I put the disconnect on the positive side not because of geometry, but because the inverter’s instructions clearly state to connect negative first then positive and to disconnect positive first then negative. If not damage may occur and the warranty is void.

4. I torque the connections with a torque wrench to spec. Battery and buss bar makers put these spec in the instructions and I suspect they have design/test reasons for doing so.

5. I used 4/O cable with gas sealed fittings. Again, the propane tank.

6. I used a marine quality, properly rated buss bar to combine all the cables.

7. I mounted the switch on a thin piece of plywood and attached it to the metal structure. If a cable were to come loose, it will contact wood, not metal.

P.S. I took that picture in the article 🙂

3 years ago

First time for everything. This time the result was a burned shore power plug. I started my set-up first check the power. Turned the breakers to off put my 50/30 dog bone into my 50 amp surge protector. Plugged it in, turned on the power all was good. Turned the power off, plugged in my cord, hooked -it up to the rig and turned the breakers on again. All good. Turned on the A/C to start to cool down the rig (it was 90) and set-up. Walked to the truck and heard a loud pop. Wife said power was off and A/C stopped. Walked to the plug to see smoke, sparks and flame! Grabbed a 4′ leveling board, flipped the breaker off, knocked the plug out of the socket and waited. Pulled the dog bone off the surge protector and looked to see the male end was charred and one tine was melted. Went to the office, they called an electrician who arrived in about 30 minutes. He opened the pedestal and found two loose connections and a melted wire. He also found an unprotected wire splice and a plug that was partly screwed into the panel through a hole that had been drilled out to fit (sort of). He replaced the parts, fixed the panel, tested all connections, voltage and gave me a new dog bone. He asked for the old one to make a pitch to the owners to have all the pedestals checked and was recommending upgrading the park to all 50 amp power during the off season. Now 3 days later, it’s still hot but our power works fine. Can’t imagine what could happened!

3 years ago
Reply to  MrDisaster

You are so correct! I guess you can be glad the Surge Protector probably did its job and cut the power off to your RV. And no telling had this happened when you weren’t at the RV. Could have come back to a burnt out SHELL or NO RV at all.

I think MIKE has talked about this stuff before and the Lack of maintenance RV Park owners do on their Pedestals. Most don’t really care, just that you show up and pay your FEE and hopefully nothing happens. I have seen pedestals wired UPSIDE Down and couldn’t plug the 50 Amp in! It is amazing at the things you see in RV Parks.

When I comment on electrical issues, I always end it with INVEST in a SURGE PROTECTOR, It will save your RV and Possibly you LIFE!

Take Care.

3 years ago

You requested feedback, so here it is: I’ve always enjoyed reading your articles, but in June, I had the pleasure of hearing you speak at the Heartland Rally in Goshen. Not only are you informative, but you are easy to listen to, and you speak with your audience, rather than lecture to them. You take the time to explain the topic at the level your group can understand, and are very patient with those who don’t get the concept right away. I agree with your statement that you didn’t teach if the students didn’t learn, but in your case, anyone who can’t learn from you, just isn’t paying attention. Thanks for a great seminar, and all the other advice you give.

3 years ago

Regarding combining plugs to pull more amps, I actually had this situation in a house, where a switch was occasionally sticking and/or arcing visibly around the toggle(!). I figured a quick swap of a defective switch, but found that the circuit still didn’t die when the designated breaker was off. In order to control twenty 150W downlights from a single switch, someone had simply combined two 15A circuits after the breakers (way overloading the 15-20A switch!). A $1 switch replacement got a lot more involved as I re-split the circuits again (not wanting 3KW of lights anyway!).

AL Simons
3 years ago

I haven’t, but only because my EMS let me know I had a wonky leg on the 50A outlet. Without that, I’d have probably had a burned plug AND possibly a toasted air conditioner. Reported this into the SVP program.

How about an SVP update at some point, Mike? How’s the effort going?

3 years ago

Speaking of the Burned Shore Power Plug! We are currently camping at a Park in Louisiana that isn’t quite 2 years old. Very Nice Place and well organized, lots of room between spaces. However, the Power Pedestals which appear to be fairly new have severe signs of wear and abuse.

The receptacle plugs are burned and of course when I went to hook up the BREAKERS were in the ON Position, meaning someone disconnected their shore power cord without turning off the breakers. In fact all the breakers (20/30/50 amp) were all on again!

People are JUST NOT LEARNING to turn these Power Pedestal Breakers off before disconnecting their Power Cords, thus causing Pedestal Plugs and Power Cords to have burnt ends.

Now, I know there are all KINDS OF “KNOW IT ALLS” out there and Park owners as well, that think the Breakers need to be left on. That is simply not the case. Turn the Breakers OFF BEFORE you connect and before you disconnect. This will prevent your Shore Power Cord Ends from becoming burnt!

OK, OFF MY SOAPBOX once again.

OH, and by the way, GET A SURGE PROTECTOR TOO! It will save your RV from Serious electrical damage!

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