Prevent dangerous RV “hot skin” condition


RV Electricity
with Mike Sokol

Dear Mike,
We recently purchased a pop-up camper. We set it up in the driveway to check things out. My daughter got a shock when she was standing on the grass and touched the camper door. I checked it out and realized that the extension cord had a bad ground wire. I hooked up an extension cord with a good ground wire, then the camper did not shock me. Exactly what’s happening here? —A Shocked Reader

Dear Shocked,
The thing to understand is that anything plugged into a power outlet has at least some leakage current to its chassis. And if there’s not some way to get rid of this current, then it turns into a voltage on the “skin” (actually the chassis) of the appliance or RV. Even the tiny iPhone will develop around 60 volts on its “skin” when plugged into a charger since there’s no ground pin on the plug. But the amount of leakage current in that case is so small (typically less a 1/1000 of an ampere or 1 mA) that you don’t feel it.

However, an RV has a lot of internal connections and appliances, all of which leak a little current to the chassis, and that current is additive. So any RV without a grounded plug can easily leak 1 to 10 mA of current to its chassis, and that would normally be shorted to ground via the ground pin on the shore power cord. If that safety ground connection is eliminated either by a non-grounded extension cord or outlet with a missing ground, then the chassis (skin) of the entire RV can become electrified with voltage.

Now, sometimes this is a harmless tingle if there’s not a lot of available current or you’re standing on dry ground. But if your feet are wet and there’s significant leakage current (much over 10 mA or 10 milli-amps) then you can be severely shocked or even electrocuted (killed) when touching anything metal on your RV and the wet ground. So every RV needs to be connected (bonded) to a proper safety ground wire in the shore power plug.

If you feel any kind of shock, or measure more than 2 to 3 volts between the RV chassis and a ground rod in the earth, then that safety ground has been interrupted somehow, and the RV can develop a hot skin voltage and turn deadly at any time without you knowing exactly when. So NEVER hook up shore power to an RV without a properly grounded extension cord, and NEVER ignore feeling a shock, since that’s a hint that the RV’s safety ground is no longer connected properly.

Let’s play safe out there….

rv-safety-764Mike Sokol is an electrical and professional sound expert with 40 years in the industry. Visit for more electrical safety tips. His excellent book RV Electrical Safety is available at