Mike, I have a question regarding the open ground condition. Do you also have to have a circuit leak, or resistive connection, or short-to-ground to have the hot-skin condition and not just an open ground? If true, you would have two problems to solve. The open ground and the circuit leak.
That's exactly right, you need two conditions to create a hot-skin condition.
The first condition would be an "open ground". That open safety ground can be inside the campsite pedestal itself from a loose connection on the back of the outlet, or a broken ground connection between the pedestal and the campground power service entrance, of it could be within your own extension cord due to a broken off ground pin or broken wire, or possibly even inside your RV itself within the power panel where the shore plug ground connection is supposed to bond to the chassis of your vehicle. But an open ground by itself won't cause a hot-skin condition; it just makes for the possibility of a hot-skin. You need a voltage source to then create a hot-skin.
This second required condition occurs when something inside your RV provides a conductive path from the "hot wire" to the vehicle chassis. The classic example would be someone driving a screw into the wall which then goes through an electric wire, producing a complete "short" to chassis ground capable of pushing 20 amps or more current. Now in that circumstance, your RV safety ground connection is supposed to shunt that current back to the service panel's Neutral to Ground bond connection, thus tripping your 20 amp circuit breaker. But if you don't have a nice solid electrical path back to the campground's service panel, then your RV chassis will happily go right up to 120 volts hot-skin potential above the earth.
The other common situation is when an appliance such as a microwave, refrigerator, or even a computer in your RV develops a leakage current inside its own power supply from the hot wire to the appliance chassis. Now since the appliance typically has its own ground pin on the power plug, this leakage voltage (typically 60 to 90 volts and maybe 10 to 50 mA current capability) will back-feed into your RV's internal grounding system. Again, if your RV has a perfect safety ground back to the main panel, this 60 to 90 volts of hot-skin potential will never occur since it's being drained to earth back at the campground's N-G bonding point. Note that this ground-fault current never really goes through the earth beneath your feet; it loops through the artificial ground plane created within the entrance service panel by the Ground Bus, Neutral Bus, and Ground Rod. That's why leveling jacks down on the dirt will do nothing to protect you from an open ground induced hot-skin condition. The dirt is a pretty poor "ground" and only remotely connected to the service panel's ground connection via the ground rod many hundreds of feet away. But the dirt beneath your feet certainly has enough conductivity to pass sufficient current (10 mA) through your heart if you touch a hot-skin electrified metal stairs or a doorknob while standing on the wet grass or dirt.
The real kicker is what I call a reflected hot-skin condition, where a campground has lost the safety ground connection from a loop of daisy-chained campsites back to its service panel entrance. In that case, you can have a single RV with a hot-to-chassis short create a hot-ground pin on multiple pedestal receptacles. And note that turning off your own campsite pedestal or RV circuit breaker panel will do nothing to stop this reflected hot-ground condition from creating a hot-skin condition on your own RV. Even installed surge and voltage protectors will NOT disconnect your RV ground from the hot-ground voltage in the pedestal. That's why I still think it's the best policy for everyone to do a voltage check on any campsite power pedestal BEFORE plugging in, and use a non-contact AC voltage tester such as a Fluke VoltAlert to confirm your RV skin is safe. And if you EVER feel the slightest shock or tingle from your RV, disconnect from shore power by pulling the plug immediately and call for a certified electrician. If they don't understand what you're talking about at the campground or say that it's OK to get shocked, break camp and get out of there. Also, call your RV service club and campground franchise to report the campsite number along with the pedestal power condition and lack of repair by the campground. I would also demand my money back from the campground since paying for a campsite with a dangerous power pedestal is silly. Don't leave a dangerous power pedestal available for the next camper to find and possibly be electrocuted.
This is such an important subject that I'm going to write it up as a full article with diagrams next week and publish it on RVtravel.com and NoShockZone.org. So if this sounds confusing right now, I'll try to clarify it in the full article.
In the meantime, never accept feeling a shock or tingle from your RV. It's a warning sign that the next touch could severely shock or kill you or a loved one.
Let's stay safe out there....
Mike Sokol
mike@noshockzone.org
