What’s a ground loop tester and do I need one?

Hey Mike,
I’ve read in several of your posts on various sites that you recommend a Ground Impedance Tester as the “Gold Standard.” What exactly is it and what does it cost? Should I use one for my own testing? —Stan B.

Stan,
So here’s the story on the Ground Loop Impedance Tester. These are pretty expensive devices for a regular home or RV owner to purchase, costing around $300 or so. But that’s certainly within the budget of any RV repair shop or even campground that wants to check their own power pedestals for correct ground.

I have Ground Loop Testers from at least four different manufacturers, and each of them operates in a similar manner. When you push a test button they dump a short 20-amp pulse of current between the 120-volt line and the ground, then measure how well the ground wire can absorb the fault current. An internal calculation gives you a reading of ground impedance in ohms. Less than 1 ohm is a good ground, but if it measures under 0.1 ohm that suggests a Bootleg Ground which also shows up as “F” for False Ground on some of them. Any impedance over 1 ohm is a code violation and should be corrected.

My favorite Ground Loop Tester is made by Ideal Industries. Here’s a short video of how their SureTest Analyzer works.

So is it worth the $325 price? Well, for troubleshooting an electrical grounding problem in an RV it can save hours of confusion. So I think that every RV repair shop should have one. Plus, for a yearly certification of electrical outlets on campground pedestals, it’s really the only way to do an accurate test. So I think that every campground should use one as part of a yearly test-and-tag procedure on every campsite pedestal. They’re available at Amazon.com.

Want to discuss this topic further, or any other RV electrical topic? Then stop by the RV Travel meetup in the “Locker Room” at the Hershey RV Show on Thursday, Sept. 14, from 11 a.m. to noon and we’ll talk shop.

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.

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