RV Electricity – Using a Non-Contact Voltage Tester


Dear Mike,
After reading your article on RV hot-skin voltage I ordered a Southwire 40126N Non-Contact Voltage Tester, but now wonder if it’s the correct tool. According to the directions it detects voltage by putting it near a hot plug. But will it also find a hot-skin voltage by putting it next to the skin of an RV? —John Baxley

Great question John,
But first a quick review of what a hot-skin/stray voltage is. Normally, the skin and chassis of your RV is within 5 volts AC of the earth. It’s the job of the ground wire in your shore power cord and pedestal to keep it down to this safe voltage. But if the ground wire is loose or broken in your electrical connection, this voltage can rise to 30, 60 or even 120 volts. Anything over 30 volts can be dangerous to your heart, so if you detect 30 volts or more, then you should disconnect your RV immediately until the problem can be corrected.

I came up with this very simple proximity hot-skin/stray voltage test nearly 10 years ago, but the manufacturers haven’t included it in their owner’s manuals yet, which is why you didn’t read about it. But you can see it here:

I have a variable AC power supply, my VW micro-bus, and several different Non-Contact Voltage testers I always recommend for my Stray Voltage Patrol. Of course there are other brands and models that will work, but let’s keep it simple for now.

I can recommend the following Non-Contact Voltage Testers, which are available in-store at Lowe’s and Home Depot, as well as Amazon.

Fluke VoltAlert 1AC-A II rated for 90 to 1,000 volts 

Klein NCVT-1 rated for 50 to 1,000 volts 

Southwire 40136N rated for 50 to 600 volts

Even though all three of these testers are rated to find potentials higher than 50 or even 90 volts, they all work great at finding a stray voltage as low as 30 volts on something as large as a campground pedestal or your RV. Watch the video above to see this in action.

These same manufacturers also make dual-range testers, such as the Southwire 40126N you mentioned. And these will also work to detect a hot-skin/stray voltage as long as you leave them in high-voltage mode. If you set them in the 24-volt low range they’ll be too sensitive for this test and you can get false positive warnings. Read the directions to make sure these are set in the high-voltage range to use them for a hot-skin/stray voltage test.

If you plan to join the Stray Voltage Patrol in any capacity, then the minimum test gear you need is a Non-Contact Voltage Tester. More on this topic later, but here’s a link to what I’ve published already about joining the Stray Voltage Patrol

Well, that’s it for now. 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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Scott Elston

Excellent. Absolutely loved reading and very helpful at the same time 🙂

D 'n C


In the video, you said you set your power supply for 30V and then demonstrated use of 3 NCVTs. All 3 alarmed, although none of the 3 advertise sensitivity below 50V. So, why are these NCVTs alarming at only 30V?


Chuck Barker

Mike, I really appreciate the information on electrical safety. On your recommendation, I purchased a smart surge protector as well as a couple of NCVTs. (Gotta have one for around the stationary house, as well!) Given the fact that the surge protector Can detect a number of problems with the power source, what would be a good protocol for using them in combination? Would it be wise to start by checking the power pedestal with the NC this first? Thanks for your advice.

Bill T.

Hi Mike,
Not sure if I found the answer to John’s question in your reply. My RV doesn’t have aluminum siding. It has pressure layered sides. Will the non contact voltage tester pick up stray voltage from the side of my RV or will I need to bring near the metal steps?

Rick Field

Thanks for your column, it’s a wealth of information. When we arrived at our rv site this week in Old Orchsrd Beach I followed your advice and ended up discovering an open ground on the pedestal. I notified the office and they got an electrician out and all was good within an hour!

Daniel Pankiewicz

Sorry Amazon picture is wrong not the text description

Daniel Pankiewicz

Your recommended Fluke VoltAlert 1AC-A II rated for 90 to 1,000 volts weblink sends the user to a Fluke VoltAlert 1AC-“E” II rated for 200 to 1,000 volts. Slightly different model.