All about non-contact voltage testers

All about non-contact voltage testers

 

From my friends at the R-Pod Owners Forum:

Mike,
My 2015 R-Pod 178 tests hot with a Fluke Meter when plugged into my 110 house circuit. It tests hot when touching the metal frame of the RV. I do not feel a shock when touching the same metal. This is quite disturbing. What do I do now? —Irish Tom

Tom,
Anytime you measure more than 2 or 3 volts AC between the chassis of your RV and the earth, there’s cause for concern. That’s because you’ve lost the connection between the chassis (skin) of the RV and the earth-grounding point at the service panel. Once that happens, then all it needs for a hot-skin chassis voltage to occur is a leakage current between the 120-volt line and the chassis. Could be a short in a wire. Could be a pinhole leak in a hot water heater element. Could be internal leakage in a microwave or inverter transformer. Once those two things happen, then all it takes is for someone to be standing on wet soil and touch the RV with a damp hand. That’s when death by electrocution is a real possibility.

If you do measure more than 2 or 3 volts AC between the earth-ground and the frame of your RV, or feel a shock when you touch the RV while standing on the ground, it’s time to immediately find and correct the problem. Please don’t become a statistic. —Mike Sokol


Mike,
OK. I have no idea what you all are talking about … using a circuit tester? Huh, what? What was broken to create a shock? Are you saying, “Don’t run around on wet ground while you have your electrical hooked up/plugged in?” What went wrong? If you’re very careful with your extension cords and keep the connections out of the water, won’t you be OK? —3peas

Ground rod

3peas,
There are basically two tests you can perform in the field for a hot-skin voltage. The gold standard test is to put a ground rod in the earth (at least 18” deep) and use a DMM (Digital Multimeter) to measure the voltage between the ground rod and the chassis of the RV. But I only do that level of testing when I’m troubleshooting a complicated wiring problem.

The quick and easy test is to use a standard sensitivity Non-Contact Voltage Tester (NCVT) and make its tip come in contact with the chassis of your RV while you’re standing on the ground.

Fluke VoltAlert

Even though the voltage sensitivity may be rated for 90 to 1,000 volts, they will generally indicate voltage (beep) when a large surface has as low as 40 volts AC on it. I’ve performed this test on literally hundreds of RVs, microphones, guitars, and household appliances, many of which I’ve created hot-skin voltages on purpose, so I know it works.  You’ve probably seen my videos here on testing an RV for hot-skin voltage with a Fluke VoltAlert. Just for fun here’s my video on testing electric guitars for a hot-skin voltage. Same basic causes and dangers as an RV hot-skin condition.

Guitar test

And even if your own shore power plug and extension cords are OK, it’s still possible that the campground pedestal or home power source you’re plugging into has lost its ground. So it’s always best to test after plugging into power. This only takes a few seconds with an NCVT, and you might find a lost ground that could endanger you and your own family, plus it could be dangerous to the next camping family who uses that same pedestal. —Mike Sokol


Mike,
I noticed our dog getting shocked while sniffing around the jack post on our pod. This was with a setup and power supply that I’d used and tested before. Went and got my NCVT tester and sure enough, the pod frame was hot. Traced it to an open ground on my heavy-duty extension cord. Fixed the broken wire and all was good.

Local hardware stores have Non Contact Voltage Testers for $10 or so, and they’re sometimes sold in conjunction with a 3-light outlet tester that will show correct wiring or an open ground. Here’s an “All in one package” at Amazon.com for $20 that should work.

Dave & Chris,
That’s a good catch on an affordable test package. Thanks for posting it. —Mike Sokol

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.

##RVT801

 

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