First off, I just bought your book on Amazon and have read 80% of it, as well as bought all the tools for testing electrical pedestals off Amazon. I love your water pressure to electrical comparison! My wife and I are going to RV full time starting next month in a Class C. Before I bought your book, I was planning on buying a Progressive Industries surge protector, the 50-amp model.
Your book explains that 50-amp and 30-amp pedestals are more than just a difference in plugs. If I buy this surge protector for 50 amp, and then come to a campsite that is 30 amp only, can I use an adapter to plug the 50-amp surge protector to the 30-amp outlet? Am I setting myself up for a big problem? I ideally don’t want to buy both a 30-amp and a 50-amp surge protector, but I really don’t want to have an issue either.
Thank you for your time, and again thanks for the book! —Doug
Thanks for your kind words. As far as teaching electricity by comparing it to water, that’s exactly how I taught myself all about voltage, current and resistance so many years ago. I came across a really old book in the library (remember those things?) about electricity when I was perhaps 10 years old, and it used water pressure and flow to explain how voltage and current worked. So a few experiments with a garden hose in the driveway got me interested in all things electrical. But back to the future (or is it the present?).
You’ve made a great choice by planning to purchase an Electrical Monitoring System (EMS) type surge protector since it will continuously test the voltage at the pedestal and shut down power to your RV if the pedestal voltage goes too high or too low, or loses the safety ground. Now, it’s not monitoring the current flow (amperage) since that’s the job of the circuit breakers in the pedestal, to watch for too much current. So the EMS unit is only concerned with monitoring the line voltages. And since the voltages on a 30-amp and 50-amp power outlet are really the same on both legs, it just won’t care if your RV is plugged into a 50-amp/240-volt outlet, or a 30-amp/120-volt outlet.
What that means is that the 50-amp surge protector you’re planning to purchase will operate perfectly on either a 50-amp or 30-amp pedestal outlet, as long as you use the appropriate dogbone adapter. In your case something like this will do the trick. You just plug the 30-amp side of the dogbone adapter into the 30-amp pedestal outlet, and the 50-amp surge protector into the 50-amp side of the dogbone adapter, and your 50-amp Shore Power Plug on the RV goes into the EMS surge protector.
The job of this dogbone adapter is to take the single 120-volt leg of a 30-amp pedestal outlet and jump it to both of the 120-volt legs in the 50-amp shore power plug of your RV. And that’s what feeds both legs of the 50-amp EMS surge protector whenever you’re plugged into a 30-amp pedestal. So no matter if you’re plugged into a 30- or 50-amp outlet, the EMS will correctly monitor the shore power for high or low voltage as well as a lost ground. Which is exactly what it’s supposed to do.
Let’s play safe out there….
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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.