Are “Little” Shocks OK?Aug 16th, 2013 | By Mike Sokol | Category: RV Safety
This series of articles is provided as a helpful educational assist in your RV travels, and is not intended to have you circumvent an electrician. The author and the No~Shock~Zone will not be held liable or responsible for any injury resulting from reader error or misuse of the information contained in these articles. If you feel you have a dangerous electrical condition in your RV or at a campground, make sure to contact a qualified, licensed electrician.
A question from an NSZ reader:
I have a Safari 40′ DP and every time I plug into shore power I feel a shock when touching any metal on the RV. For instance, if I open the under bay door and touch the inside latch I get zapped. Can anyone tell me what would make this happen. Is it really dangerous since it’s only a “little” shock?
Thanks in advance,
First of all, ANY shock is dangerous. There’s really no such thing as a little shock being OK. You and your family are playing a game of electrical Russian Roulette, and that rarely ends well. You need to find and fix the electrical problem causing this right now, before somebody gets seriously hurt or killed. In the USA alone there are 1,000 deaths per year from electrocution, and 4,000 more injured seriously enough to require hospitalization. And many of those electrocutions are from known “little shock” situations that became deadly.
To see something REALLY interesting, here’s a video where I created an RV hot-skin condition ON PURPOSE. Yes, I regularly do these type of experiments to find better ways to measure dangerous electrical conditions and learn how to fix them. http://www.youtube.com/watch?v=Y8h64X33aKg
FYI: It only takes about 20 mA of electrical current (20/1000 of an amp) to cause your body to clamp down and not be able to let go of an energized wire. And 30 mA of current (30/1000 of an amp) for a few seconds can cause your heart to go into fibrillation. So just 30 volts AC with 30 mA of current can kill you if your hands and feet are wet. That’s only about 1 watt, less than the power of a small nightlight bulb.
An RV chassis and skin with ANY significant voltage above earth potential (2 volts is max) is proof that you’ve lost your RV’s safety ground connection. Now, by itself an open ground connection won’t cause an RV hot-skin voltage condition, but nearly anything inside your RV plugged into its electrical system will cause some leakage current to the RV chassis-ground. And that leakage will show up as a hot-skin voltage of varying degree. The really dangerous thing is that sometimes those can be high-impedance leakage currents that aren’t particularly dangerous. And that’s when you feel a “little” shock. However, that same “little” current can quickly become low-impedance/high-current leakage in a heartbeat, and that will almost certainly kill you if you touch the RV with wet hands and feet. It’s just a matter of degree, and you never know what that degree is. So any feeling of shocks from your RV or appliance is a warning to turn off the circuit breakers and disconnect the power plug immediately.
If you do have a proper RV safety ground back to the service panel, then it should be impossible to develop more than 1 or 2 volts on your RV skin. It will harmlessly drain away the small currents from normal high-impedance appliance leakage, as well as trip the circuit breaker form huge currents that result from abnormal low-impedance leakage, such as a screw driven through a wire inside your wall.
So if you measure more than 2 volts between the earth and the chassis of your RV there’s a serious problem with your safety ground. This is usually as simple as a broken or loose ground contact on your extension cord or dog-bone adapter, but can also be due to a problem in your campsite pedestal or home power outlet. Old garages are especially dangerous since they can be ungrounded for years without you knowing it, and the first time you plug an RV into it there can be a deadly hot-skin condition. And certainly a worn RV pedestal outlet can have corrosion or loose contacts, and that can cause an RV hot-skin condition.
There’s one other really dangerous mis-wiring condition that I’ve seen at dozens of garages and concert stages around the country. It’s something I call an RPBG (Reverse Polarity Bootleg Ground). This can happen when a DIY guy or old electrician tries to add a grounded outlet to a pre 1970 non-grounded electrical system by simply putting a jumper wire between the ground and neutral screws on the back of the outlet. But if the black and white wires are accidentally reversed, then the hot wire is sitting at zero volts, and the ground and neutral wires are at 120 volts. Note this is not the same thing as a simple “Reversed Phase” where the Hot and Neutral Wires are reversed, but the Ground Wire is connected properly. That condition alone will NOT cause a hot skin condition if all other wiring is done correctly.
However, you can’t find this RPBG condition using a 3-light outlet tester and a voltmeter measuring between H-N, H-G and G-N will report the outlet as safe, when in fact it will electrify anything you plug into it that has a ground plug. And there’s no surge or voltage protector product on the market that will detect or disconnect your RV from a RPBG outlet. They will report that everything is fine with an RPBG outlet, when in fact your entire RV and connected tow vehicle has been hot-skin electrified to 120-volts. The simplest way to detect this dangerous condition is by using a Non Contact Voltage Tester as I demonstrate in the video above.
See my complete article about RPBG outlets and how to find them on Gary Bunzer’s website (the RV Doctor) at http://www.rvdoctor.com/2001/07/friends-of-gary-mike.html or my EC&M Magazine article for electrical contractors and inspectors at http://ecmweb.com/contractor/failures-outlet-testing-exposed.
The bottom line is NEVER accept feeling any shock from an RV or appliance. A shock is a warning that the next time somebody touches your RV they could very well die from electrocution. I think it’s socially irresponsible to expose your family and others to this potentially deadly situation, so get it repaired immediately. If you’re not 100% sure that you can measure and work around live electricity safely, then please contact a licensed electrician or RV technician immediately. The life you save could be your own, or that of a friend or family member.
No Shock Zone