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.
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…