Important - check this every time you set up

Good question.  It wouldn't cost more than the already-required LPG/smoke/CO detectors.  Only catch is it would only work while you had a firm grip on it, while standing on the ground outside.  Two possible solutions - add a large touch pad just above the power connection so you could plug in, press your hand to the pad and get a read-out just above it.  And/or redesign the door handle so it is insulated, and every time you grab it you get a readout above the handle.  There are issues - would it work if the sensor was wet or had road grime on it, what if you are using a plastic step-stool in front of the door, etc.  But there are solutions - put the sensor inside a cover, and maybe only putting it above the power connector is the better location even though it would only get checked once and not every time you get in the camper.

Worth repeating in short form, so nobody misses it.  

Would a surge suppressor have any effect in this situation?

Originally posted by Tars Tarkas An additional fun feature of these testers is that when you have them on while driving under high voltage electric lines -- the kind that run from tower to tower rather than pole to pole -- they will light up and beep. TT

True, and that's because your body or vehicle is actually elevated to several thousand volts above earth potential while standing under power lines. No kidding. In fact, if you park your tow vehicle and RV directly under high-tension power lines (yup, those big ones) you can get a pretty good shock while standing on the ground in bare feet or wet shoes and touching the door handle. I've discussed this phenomenon with a number of Power Company Engineers who say that the current is supposed to be less than 5 mA at the normal 14 ft minimum wire distance to ground suggested by the utilities. However, since that power line could have up to 500,000 volts on it (yup, half-a-million volts), then you could get up to 10,000 volts bias on your vehicle (but at less than 5 mA current). So while the shock could startle you, it shouldn't be dangerous. I'm going to do an experiment this summer showing how a car spark plug attached to the bumper of an RV will spark continuously when connected to a ground rod. Too much fun...

Interesting stuff, eh?

Originally posted by techntrek Something I didn't make clear in my first post, if any camper (or an appliance, or the shell of the power pedestal at a campground) tests positive it means 2 things.  Problem one, there is a fault somewhere which has electrified the exterior metal.  Problem two, the ground ("equipment grounding conductor") is not connected properly so it isn't doing its job to prevent problem one from killing you.  So if the tester gives you a positive reading you have 2 problems to fix.  Unplug the camper immediately without touching it, or the power pedestal, only the cord.

Just a few clarifications. First of all, while you might think there needs to be an internal hot-to-ground fault to produce the voltage in the first place, that's not entirely true. ANY appliance plugged into a power plug can have some current leakage that will produce a voltage of some level. But the AMOUNT of fault current is limited by UL Labs to less than 0.75 mA for an "ungrounded appliance" such as your iPhone charger, or less than 3.5 mA for a "grounded appliance" for something like your microwave oven. Generally, anything plugged into an electrical outlet and NOT malfunctioning will have its chassis migrate to around 1/2 of line voltage. So it's perfectly normal (but somewhat scary) to measure 60 volts AC on the body of your iPhone while plugged into its wall-wart charger. But because the maximum leakage current is supposed to be under 0.75 mA, that's right below the current threshold that most people will notice a shock.

On the other hand, a microwave oven (or any other grounded appliance) can leak up to 3.5 mA of fault current and still be considered "safe" by UL standards. This will generally produce the same 60 volts on the chassis if left ungrounded, but that 3.5 mA of current at 60 volts will produce a very noticeable, but not dangerous shock. And all these leakage currents are additive, so if your RV has a broken ground wire (EGC - Equipment Grounding Conductor) then everything plugged into your RV can leak more current to the chassis, and it's entirely possible to have 20 or 30 mA of leakage fault current available even if nothing is really "wrong". I call this a low-current (high impedance) fault, which can be painful but generally not deadly. Now, if your EGC is in place, then that 20 or 30 mA of current will be drained harmlessly to the grounding point of your service panel. However, if there's no ground path in your power cord and you touch anything metal on your RV while standing on damp ground or grass, then you can feel a very big shock. Now remember that 10 mA is a pretty good shock, and 20 mA will cause your hand to clamp down on a wire or ladder rung and not be able to let go, and 30 mA through your chest cavity for a few seconds almost guarantees heart fibrillation and death in minutes if CPR isn't immediately begun, so even these "low current" leakage voltages can get dangerous.

The second type of ground fault is a high-current (low impedance) short from a hot wire to the chassis inside an appliance or your RV's electrical system. This often happens when a screw is driven through a wire in the wall, or the insulation of a wire has worn through from road vibration, or a cable was pinched in an access door, etc... This type of high-current fault can reach circuit breaker amperage level, making 20 amps (or more) of current available at 120-volts. Without a low-resistance ground connection back to the electrical service panel, touching your RV is equivalent to sticking your finger in the light socket while standing in your bathtub full of water. Since a human body has somewhere around 1,000 ohms resistance with wet hands/feet, that 120-volts will produce upwards of 100 mA of fault current through your body, which is WAY above safe limits. So unless you're pulled off the energized chassis within a few seconds and CPR started within a few minutes, you're dead from electrocution.

Now, this hot-skin test isn't something you need to do every time you walk up to your RV, but I would certainly test every pedestal receptacle ground for improper voltage BEFORE plugging in your RV power cord. Then do a quick check on the chassis/skin of your RV with a NCVT such as a Fluke VoltAlert or Klein NCV-1 to make sure your extension cord ground is good. If there's a voltage on your RV skin/chassis while plugged in, then immediately turn off the pedestal circuit breaker, unplug your shore power connection, and contact the campground manager. After your initial test while making camp, you should only have to pull our your NCVT if you feel ANY kind of shock from your RV while still in camp at the same location. And the same goes for when you visit any of your RVing buddies at their campsites. If you feel ANY tingle at all while touching their RV, then pull out your trusty NCVT and do a hot-skin test for them. If it beeps and lights up, then they have a hot-skin condition of at least 40 volts, which could be a low-current leakage condition (shocks but doesn't kill you) or a high-current leakage condition (deadly under all damp conditions). But for sure they have lost their ground connection and need to power down and unplug immediately. You will NEVER read more than a few volts above earth potential on the skin/chassis of a properly grounded RV. If you do measure more than a few volts, then your ground is broken for some reason.  

Why doesn't your GFCI protect you from these situations. That's another story, but remember there's no GFCI required on a 30-amp TT-30 outlet, it's only required on the 20-amp outlet at the pedestal.