NCVT

Here's my video on the Fluke VoltAlert 1AC-A II that I typically use for hot-skin testing.
https://www.youtube.com/watch?v=obeh9m4OMv4

Basically, any NCVT that has a 90 to 600 or 1,000 volt range should work. Every one of these that I've tested will beep when held next to a large surface (your RV) somewhere around 40 volts. For instance, I also use a Klein NCVT-1 a lot which is rated for 90 volts when testing something small like a wire, but will beep at 40 volts when held close to a large surface. Klein also makes an NCVT-2 dual-range tester that will find wires below 24 volts, and these will find an RV hot-skin around 20 volts. But they're a little too complicated for the casual user. I also have a few variable sensitivity NCVT's from other manufacturers, but they need to be calibrated against a known-voltage every time you use it. I don't think that anyone (not even me) wants to go through that procedure. Far better to get something that's factory calibrated to a known sensitivity.

Also, even though I use them I'm not a big fan of "Always On" testers. That's because you don't know if the battery has died while the tester is in your glove compartment. I really like something with an indicator light that lets you know that the battery is good and that it's turned on. And you really should double check that ANY NCVT is operating properly by poking it at a known AC power source before you rely on it to test an RV for hot-skin voltage. There will be an occasional operational failure in any electronic device, and you don't want a false negative to lull you into a sense of security.

Finally, I don't consider an NCVT to be the first or only test you do on campground power. You really should meter any new outlet you're going to plug into to check for correct voltage and H-N polarity. If anything looks goofy, do not proceed to plug in your RV. And I would certainly advise everyone to consider purchasing a good EMS (Electrical Management System) to help protect their RV investment. The combination of a Progressive Industries EMS with relay disconnect and a Fluke VoltAlert is what I consider to be the Gold Standard in consumer RV power testing.

Mike Sokol