Friday, July 1, 2022

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RVelectricity: Open neutral danger account from a reader…

Dear Readers,
This picture and story just showed up on my RVelectricity Facebook group. It’s a great reminder of why you really need an advanced surge protector on your RV (commonly called an EMS or Total Power Protection).

Note that this particular pedestal would have measured perfectly fine with an AC meter, but once the RV was hooked up and drawing power, the neutral conductor opened up and applied way more than 120 volts to one-half of the RV’s electrical system. Unfortunately, many campgrounds don’t use licensed electricians for their electrical work, so this sort of mis-wiring is more common that you might imagine. And few campground pedestals are inspected or maintained on any sort of regular schedule, so any time you plug into a campground pedestal you roll the dice.

These advanced surge protectors are sold by the big three companies: Progressive Industries, Surge Guard and Hughes Watchdog. I like the Surge Guard products the best because I’ve tested all three of them in my FunkWorks Lab and think they have the best engineering.

In any event, I think that the $300 to $400 cost of an advanced surge protector is cheap insurance to help keep your RV’s electrical system from frying. And open neutral on a 50-amp service will almost certainly cause a lot of expensive damage that could take months to even get the repair parts. So be proactive and don’t wait until electrical damage occurs.


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Here’s what recently posted on my RVelectricity Facebook group…

I finally decided that I should be using a power analyzer before connecting the RV. First time I’ve ever connected to a 50A service with an open neutral. After spending the last 50+ years as an electrician you would think I’d know better than hook into an unknown source. But really, that’s what we do every time we move to another site.

We were in the trailer just getting set up when the bathroom filled up with smoke! We thought one of the neighbors was burning popcorn. I went outside and couldn’t smell it anymore. Came back inside and sniffed my way to the bathroom door. The good news is that our trailer didn’t burn up and we can get through this trip without having to go home. Weather is perfect, and one of my golf teammates is here to visit with.

Park manager was here earlier and it sounds like they will cover our repair costs. Nice start to the 72nd year!

It’s unclear in the photo but looks to me like last time there was an issue with this receptacle, they replaced it with a household style rather than a RV pedestal style. The wires they used for 50A were #10 THHN. The handyman would probably have been ok for a while longer if he would have replaced the burnt up feeder neutral and melted neutral buss.

All we lost was the power converter and the circuit board in a Fantastic fan. It could have been so much worse. I’ll be installing a hinged access door to the converter, so if future issues arise, I can get an extinguisher to it quicker.

Be safe, folks! – Jeff

Thanks for your great write-up, Jeff. Let’s play safe out there….

Send your questions to me at my new RVelectricity forum here.

Mike Sokol is an electrical and professional sound expert with 50+ years in the industry. His excellent book RV Electrical Safety is available at Amazon.com. For more info on Mike’s qualifications as an electrical expert, click here.

For information on how to support RVelectricity and No~Shock~Zone articles, seminars and videos, please click the I Like Mike Campaign.

##RVT1056

 

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Timothy Smith
19 days ago

Would there ever be a time when it would be beneficial to ground the RV, and why?

Mike Sokol
19 days ago
Reply to  Timothy Smith

Not really. The earth itself is a pretty poor ground, so a grounding rod will typically have an impedance of 25 to 100 ohms. So that would not create enough fault current to trip a circuit breaker in the event of a hot-to-chassis short circuit. Instead it would create an additional hazard of step potential voltage encircling the ground rod by perhaps a dozen feet. In that case, walking close to the RV could shock you foot to foot, even without touching the RV itself. So a grounding rod attached to an RV can create an additional shock hazard if the shore power cord’s EGC ground/bond connection fails and there’s an internal short circuit inside the RV.
BTW: I’ve set up this experiment in my own backyard and have verified that’s how it works.

Last edited 19 days ago by Mike Sokol
tom
20 days ago

FMCA Tucson rally had multiple problems with the generator supplied service. Those with surge protectors survived, the others, not so much.

Mike Sokol
20 days ago
Reply to  tom

Please send details of what happened at the FMCA Tucson Rally to mike (at) noshockzone (dot) org

Mike Sokol
19 days ago
Reply to  tom

Tom, did this occur at the FMCA Rally this spring or an earlier one? I would like to investigate what happened.

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