Power pedestal testing (including at COE campgrounds), Part 3

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By Mike Sokol
Here’s Part 3 of my article about testing pedestals, which includes U.S Army Corps of Engineers (COE) campgrounds that won’t allow you to use your own meter probes. For a review of Part 2 of the article, click here.

As a recap, you might remember that some Corps of Engineers campgrounds are no longer allowing you to probe their campground pedestals for proper voltage before plugging in your RV. But they insist that since these campground pedestals are checked for proper operation yearly there’s nothing to worry about. This trend of not allowing you to use meter probes on a pedestal is for another discussion, but I’ve found a pretty slick way to get around the measurement issue that’s better in the long run.

While you’re not allowed to use meter probes to measure a pedestal outlet at some COE campgrounds, you ARE allowed to plug in something like a Surge Guard® suppressor first that includes on-board voltage metering with a display screen. Note that this is a Surge Guard® 34830 (120V, 30 Amp) and 34850 (120/240V, 50 Amp) which not only includes surge protection from voltage spikes, it also includes a contactor (basically, a big relay) that can disconnect your RV from shore power in the event of a pedestal voltage malfunction. This is what I call a “Smart Surge Protector” since it includes a microprocessor which monitors the voltage and provides a readout showing voltage, amperage, polarity, etc. – basically, everything you would test using a voltmeter.

You can take this type of Surge Guard® in either the 30-amp or 50-amp version and plug it into the campground pedestal first, without even pulling your RV into the parking slot if you choose not to. It will give you a full readout of the pedestal power quality without getting out your meter probes. However, it still can’t detect an RPBG (Reverse Polarity Bootleg Ground) that you might come across if you plug into your friend’s old garage outlet while parked in his driveway. But more on that momentarily.

For this type of COE campground testing you don’t want to get what I call a “Basic Surge Protector” which doesn’t have a voltage readout, nor does it have a way to disconnect your RV from pedestal power. An example of that would be the Surge Guard® 44260, 44270, 44280 and 44290, which is an excellent diagnostic tool and does include MOV spike protection as well as indicator lights for polarity and ground. However, it doesn’t have a way to measure the actual voltage of the pedestal, nor can it disconnect your RV from a voltage that’s too high or too low. You need a Surge Guard® “Smart Surge Protector” (above) with a voltage readout and a relay. 

But remember that NO surge protector currently on the market can detect or disconnect your RV from an RPBG miswiring condition. I identified and named this dangerous condition over 5 years ago, but the industry has been slow to understand how it occurs and why it’s dangerous. For an in-depth description of RPBG miswiring and how to detect it, see my article in Electrical Contracting & Maintenance Magazine.

You should never see an RPBG at a campground, but you can expect to find them in some pre-1970s homes that have had their old non-grounded wall outlets “upgraded” to grounded ones. Unscrupulous electricians often would just install a bootleg jumper between the neutral and ground screws on the new receptacle, rather than running a proper grounded electric line back to the service panel breaker box. However, a simple $20 NCVT (Non Contact Voltage Tester) such as the Klein® NCVT-1 can easily identify an RPBG miswiring condition in just a few seconds that will cause a very dangerous hot-skin voltage on your RV. For a review of my July article on how to use a NCVT to find a Hot-Skin voltage click here.

Let’s play safe out there….

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.

##RVT816

 

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Charles Turner
2 years ago

One park power problem I see frequently is simply worn or bent prongs in the outlet. Meter testing will not reveal this problem. If there is inadequate pressure – heat will be created at the contact points. Usual proof of this conditions is burnt plugs. I carry a milled piece of plastic that meets 30 and 50 amp plug specs (.05″ I think). Before I plug in – breakers off – I insert my mechanical tester. It should have good and tight feel for all two or three flat blade contact points.

Dr4Film ----- Richard
2 years ago

Mike, maybe you can shed some light on this situation that a friend of mine has encountered at one location. I had built a Power/Pedestal Tester for him to use prior to plugging his coach into the pedestal. Here is the link to that Tester.

https://www.myrv.us/electric/Pg/tester_50amp.htm

He used the tester on the pedestal first and everything checked OK. He then plugged his coach in and the Progressive Industries EMS-HW-50C gave him an E-1 error code (Reverse Polarity). So he tested the pedestal directly behind his with his tester and got the same OK then plugged his coach in and everything was fine. How can this happen?

If the first pedestal truly had a reverse polarity condition, two things would not work correctly on the Power/Pedestal Tester. The light on the top would not NOT light up as that is powered by the two HOT legs of the 230 VAC line. Plus the two Polarity Testers plugged into Leg #1 and Leg #2 would show an error since one of the HOT legs would be reversed with the Neutral wire.

Any ideas other than to say that his PI EMS-HW-50C was at fault?

Thanks for any advice. I am stumped.

Dr4Film —– Richard

Dr4Film ----- Richard
2 years ago

Mike, maybe you can shed some light on this situation that a friend of mine has encountered at one location. I had built a Power/Pedestal Tester for him to use prior to plugging his coach into the pedestal. Here is the link to that Tester.

https://www.myrv.us/electric/Pg/tester_50amp.htm

He used the tester on the pedestal first and everything checked OK. He then plugged his coach in and the Progressive Industries EMS-HW-50C gave him an E-1 error code (Reverse Polarity). So he tested the pedestal directly behind his with his tester and got the same OK then plugged his coach in and everything was fine. How can this happen?

If the first pedestal truly had a reverse polarity condition, two things would not work correctly on the Power/Pedestal Tester. The light on the top would not NOT light up as that is powered by the two HOT legs of the 230 VAC line. Plus the two Polarity Testers plugged into Leg #1 and Leg #2 would show an error since one of the HOT legs would be reversed with the Neutral wire.

Any ideas other than to say that his PI EMS-HW-50C was at fault?

Thanks for any advice. I am stumped.

Dr4Fi;m —– Richard

Tommy Molnar
2 years ago

Richard, I like your idea and ‘invention’ I have only 30 amp service on our travel trailer. How much trouble would it be for me to make one of these for 30 amp service?.