In part one of this topic, I shared the story of my shocking rainy day experience when I entered the mobile home I lived in as a young boy.  With the absence of appropriate test equipment to test for a hot skin condition, we, unfortunately, become the living tester.  At best, we may feel just a tingle. At the worst, we may experience a serious injury or death.

Discussed here are two important pieces of test equipment that any toolbox should have, and instructions on how to use them to test for a hot skin condition.

Voltmeter/Multimeter

Every RVer needs a voltmeter or a multimeter in their toolbox.  The best and simplest models are auto-ranging.  Auto-ranging multimeters eliminate the possibility of selecting the wrong voltage range that can occur with other range selecting models most commonly available. I have been using a Fluke 73 since 1985 when I entered the US Army’s electronics and computer systems repair training at Fort Gordon, GA.  With that said, I will discuss using the standard voltmeter with multiple range selections.

To use a standard voltmeter, you will need to set it to measure AC voltage.  Note that a hot skin condition will typically be less than 120 volts, and therefore the 200-volt AC setting will be fine.

Plug the black probe into the black COM connection on the meter and the red probe into the RED VOLTS connection on the meter. Caution: Never plug into the 10-amp connection, and never set the meter dial to amps or ohms for this test.  That is for advanced testing only, and you will only blow out the meter’s fuse if you try to test for voltage in this manner.

If you are close enough to any metal going into the earth, such as the exterior of the pedestal power box, or a metal water pipe, poke it firmly with the sharp tip of the black probe.  You will need to punch through any rust or paint, so an exterior bolt or machine screw is usually a good choice.  Now without touching the body of your RV with your hand, poke the skin of your RV with the sharp tip of the red probe. Again, this needs to make a connection to the metal skin or component of your RV, so if you want to avoid making little holes in your paint job pick a spot like a trailer hitch or the trailer’s frame.

Next, while both probes are making metal contact, you should read very close to 0 (Zero) volts.  The National Electrical Code allows up to 2 volts on the ground, so 1 to 2 volts is safe. If, however, you read 10 volts, 50 volts or 120 volts, it is time to back away from the RV, turn off the circuit breaker, pull the power plug and immediately get the campsite electrician to find out what is wrong. If he tells you that 50 volts on the skin of your RV is fine, demand your money back, break camp, and get out of there.  Do not let your family or pets enter an RV with a hot skin condition.  Also, it is a good idea to alert your local RV association that a campground has a dangerous power condition. This way you help the next RVer, too.

Non-Contact Tester

While a digital voltmeter is the first choice method for testing hot skin conditions, it must be used exactly right, or it can give you a false sense of security. Therefore, perhaps the easiest and best way to check for an RV hot skin is by using a non-contact AC tester such as the Klein Tools NCVT-3 Dual Range Non-Contact Voltage Tester with flashlight. This Klein Tools tester automatically detects and indicates AC voltage from 12 to 1000 volts. These testers look like a fat pen with a plastic tip and are available at Amazon. Most have a blinking light and beeper that makes noise when the tip is held near an energized circuit.

Note: Avoid getting a non-contact voltage tester that does not have at least a minimum 12-volt AC detection.

Before using, ensure the battery is good after the tester turned on.  If the battery is bad, the light will flash, and the speaker will chirp a few times and then turn off. If indicators do not function, then replace the battery.

Detailed Klein Tools instructions can be watched on this YouTube video or download and view this PDF file.

Now, gripping the tester firmly in one hand while standing on the ground, move the plastic tip until it is touching anything metal around your RV.  This could be an aluminum screen door, the exterior of an Airstream or the steel of the trailer hitch.  With a non-contact tester, you do not have to punch through the layer of paint, rust or plastic.  If your RV has more than 12 volts on the skin, the tester will light up and start beeping.

Important to Know

Now, here is a couple of warnings about using non-contact testers to check for hot skin conditions.

• These testers need to have your hand wrapped around them to sense the earth ground, so if you hold them with just the tips of your fingers, it is possible to get a false-safe reading.
• Non-contact testers need your feet to be near the ground to know the actual earth potential, so if you are standing on a fiberglass ladder, they will not read properly. 

Additionally, since non-contact testers are looking for the voltage difference between your hand and the plastic tip of the probe, if you are standing inside an RV with a hot skin and you test your galley sink, they will not indicate trouble when indeed there is.  Therefore, always grip the non-contact tester firmly in your hand while standing on the ground outside your RV. Moreover, if your vehicle has as little as 12 volts of hot skin potential, the tester should alert you to the danger even without physically touching your RV.  You can just slip your Klein Tools pen in your pocket and use it to quickly test any RV in the campground you might be visiting.  It only takes a few seconds to test for a hot skin problem this way, and you may save another RV owner’s life.

If you missed it, read part 1, RV Electrical Safety and Hot Skin Condition

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