Originally Posted by garbonz
what model do you recommend. I am a bit confused about the voltage ranges. One has a 90-1000 range and I was thinking we would want much lower.
Actually, what you really want is the 90 to 1,000 volt range. That's exactly what I use in all of my demonstrations. Surprisingly, even though it's listed for 90 volts on the low side, that sensitivity is for Romex cable without a lot of surface area. As soon as you electrify something large (like a guitar amp or an RV) there's so much square footage that a 90-1,000 Volt NCVT will work down to 40 volts AC. And none of the NCVT manufacturers I talked to seemed to be aware of this face. Pretty interesting, isn't it.
They do make low-voltage NCVTs that read down to 20 or even 5 volts AC. However, they're too sensitive to tell the difference between the hot and neutral contacts in an outlet. They beep if you get anywhere near the front of a hot outlet, so they're not useful for polarity testing.
However, if you want to be able to detect lower voltages on your RV while still retaining the ability to check absolute outlet polarity, Klein makes a dual-range tester called an NCVT-2 which can be set to high or low voltage ranges. It's a little more complicated to operate, but offers more flexibility since there are two voltage ranges. It will find RV hot-skin conditions down to 20 volts or less.
Let me know what Non Contact Voltage Tester you end up with.