Important - check this every time you set up

Originally posted by Kermit When checking the voltage of a possible hot skin, what's the proper way to test if you don't have a good earth ground near by or your multimeter cords aren't long enough?

A NCVT such as a Fluke VoltAlert gets its ground reference by coupling through your feet to the ground, which is why you need to grip the tester in your hand. For a voltmeter test, a screwdriver in the ground will suffice for earth reference. If you're in dry soil, dump a gallon of water on the dirt first to improve conductivity. Please note that this is NOT a true ground rod and won't protect you from a hot-skin current leakage. It's a high-impedance earth reference at best, but should give you an accurate earth potential measurement using a modern digital voltmeter. Don't use a solenoid tester for this measurement as it has too low of an impedance for this type of quickie earth ground. 

Originally posted by Kermit I have a no touch cheap tester that seems to work well for testing the power outlets. I thought i had a hot skin condition this past weekend on our trip. The 30 amp outlet at the power post had proper polarity however I was getting a positive test with my no touch tester around the steps,door frame, and frame behind the steps.

Everyone should be aware that reversed Hot-Neutral polarity by itself WILL NOT cause a hot skin condition of any kind. It will, however, endanger the life of any technician working inside an open electrical panel that's powered up.

Also, it's important that your NCVT is calibrated against some known standard. Some of them have higher sensitivity than others and thus there's no easy way to predict the actual voltage they'll trigger on with various energized surface areas. Even with a common NCVT, there will be a lot of trigger voltage variance depending on how large of a surface area is energized. If you get ANY NCVT beep/flash touching the tester tip to ANY part of your RV, then I would suspect you have at least 40-volts hot-skin. Usually, beeping at 4 inches away from an RV chassis suggests around 60 volts, 8 inches away suggests 80 volts, and 1 to 2 feet away suggests 120-volts. Of course, an RV with a totally metal skin will offer a much larger energized surface than a fiberglass RV. So an Airstream with an aluminum body at 120-volt hot-skin will light up a tester from 2 feet away, but your R-pod with 120-volts might only do it from 1 ft away. 

However, the only way to know for sure is to do exactly what you propose... measure between earth ground and the RV chassis with an actual voltmeter. Remember that you'll need to poke through any paint or rust on the RV to get an accurate reading, so I've found that the lug-nuts on the wheels to be a good spot to poke a meter probe that won't damage any cosmetics. No need to try this at multiple spots on your RV. If it tests high at one spot, then it will be everywhere. Measuring any more than 2 or 3 volts from the RV chassis to an earth ground rod reference is suspicious and needs to be looked at much closer.

As an example, here's a video of me testing a 40-ft RV for various hot-skin voltages using a Fluke VoltAlert. http://www.youtube.com/watch?v=Y8h64X33aKg Kids, don't try this at home as it's a VERY dangerous experiment to do. However, I do perform this demonstration in my NO~Shock~Zone clinics using various RVs at hand. It's a real crowd pleaser...

 

This was definitely a wake up, slap in the face revelation for me after finding I had a hot skin situation in my driveway just because I was trying to save a few dollars with my extension cord. Really pretty stupid considering I just ordered a 25 foot proper extension for $36.00.

Assuming the outlets are wired correctly, then a broken ground is likely the only problem.  This is the situation I encountered at home last summer.  The best way to test for this is with a voltmeter - testing for continuity between a known good ground connection (another outlet or the enclosure) and the ground in question.  Or testing for continuity with the neutral.  Or, testing for voltage between the hot leg and the ground pin.  A plug-in tester would also identify a broken ground, probably doing the same thing as the last test I mentioned.

Mike,