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electrical short?

Maurice45
Explorer
Explorer
I was getting my 5th wheel eready for our fall trip thia AM and while kneeling beside the trailer I touched a metal panel and got a slight electrical tingle. Not enought to hurt me but a concern neverthe less. Any ideas as to the problem/solution?
40 REPLIES 40

Harvard
Explorer
Explorer
Hot skin is an indication of an open ground wire where the chassis is floating and not grounded.

SKIRMISH
Explorer
Explorer
I know this is an old thread but mine had been doing that since we got it, touch the frame, bumper, step or anything, even the dog got a shock sniffing the step.
So I got bored to today and went and put a meter on the frame and sure enough had about 9 volts running through it so I tested it by plugging in the generator and it didn't do it, it was only when plugged in to shore power. All I did was take off the electric box cover where the power goes into the MH and tighten all the big wire nuts and tested it again and everything is fine. I'm so lazy it only took me 10 years. ๐Ÿ˜„

jmsokol
Explorer
Explorer
I'm Mike Sokol, the author of the hot-skin link posted above. PLEASE don't accept any shocks or tingles from your RVs. At the very least, the OP has an open or high-impedance safety ground connection between the frame of the trailer and the neutral-ground bonding point in the electric service panel. This can occur in a lot of different places, but usual suspects are any dog-bone or pigtail adapters, extension cords with broken ground pints, power receptacles with unconnected grounds, and a poor connection inside your RV's breaker panel where the green ground wire is bonded to the chassis. Note that the white neutral wire is NEVER bonded to the chassis. If your RV is properly safety grounded, you will NEVER feel any kind of shock to earth. I have a very simple test method using a brake light bulb for checking all extension cords, adapters, and chassis bonds for a low-impedance connection that will sustain fault currents. I'll post that later today on http://www.NoShockZone.org

Secondly, as a previous poster noted, there must be a source of this voltage. And it's perfectly normal for ALL appliances to leak current to their chassis frames. Virtually every microwave, television, phone charger, inverter, and even a slow cooker has a small amount of this leakage and if ungrounded will float up around 40 to 80 volts above earth potential. How much current is leaking determines if you get a tingle, a serious shock, or death by electrocution. Typically, an appliance will leak less than 1 mA of current, but that can quickly change with any damage to the appliance or electronic failure, and certainly water in a junction box can cause all kinds of current leakage. Plus this current leakage is additive, so every additional appliance or electrical gadget you turn on will add a little more leakage current. Even a typical "surge strip" will leak current to ground, and if plugged into an ungrounded receptacle will create a 60 volt chassis potential. Seems crazy, but that's how it all works. Also, NEVER plug your RV into an ungrounded extension cord to check for these leakage currents. However, you can use a clamp-ammeter on the ground wire of the extension cord to check for these leakage currents. And yes, if the additive currents exceed around 5 mA, then your RV will trip a GFCI that's normally on all exterior 20-amp receptacles. That does not mean that the GFCI is wrong, since it's doing exactly what it's supposed to.

Finally, there's one more VERY dangerous mis-wiring condition that can turn ANY RV into a killer. I've identified something I call an RPBG outlet (Reverse Polarity Bootleg Ground) which sometimes happens in pre 1970's building and campground wiring. An RPBG outlet can occur when an older 2-wire outlet was upgraded to a 3-wire grounded one. The electricians were supposed to run a new grounded wire to the outlet box, but many cheated by simply installing a jumper between the ground and neutral screws. That's a violation of code, but not immediately dangerous unless the neutral conductor is opened or corroded. But if the hot (black) and neutral (white) wires were accidentally reversed in the walls somewhere (more common than you might think) then the hot contact will be a 0-volts, while the ground and neutral contacts will be at 120-volts. So anything with a ground plug, such as your RV, will appear to operate normally, but its chassis will be hot-skin electrified to 120-volts with full current (20 or more amps). The really crazy thing is that any 3-light tester, voltmeter or even a professional Ground Impedance Tester won't be able to tell if you have a RPBG and will say that everything is safe, when in fact your RV's chassis is at 120-volts above earth ground. Even the most expensive RV surge/voltage protectors WILL NOT find or disconnect your RV from this RPBG outlet induced hot-skin voltage. The only way to find an RPBG is to measure between your RV and earth ground. By far the easiest and safest way is to use a NCVT (Non Contact Voltage Tester) such as a Fluke VoltAlert (90 to 1000 volt model) to check your RV for a hot-skin condition. See my video at http://www.youtube.com/watch?v=Y8h64X33aKg where I hot-skin electrify a 40-ft RV. Here's my article about RPBG outlets published by Gary Bunzer (The RV Doctor) at http://www.rvdoctor.com/2001/07/friends-of-gary-mike.html. And here's my latest article at EC&M (Electrical Construction & Maintenance) Magazine where I describe this problem to electricians and electrical inspectors. http://ecmweb.com/contractor/failures-outlet-testing-exposed Hard to believe, but until I started writing about this last year, the entire electrical industry appeared to be unaware of how and why these RPBG conditions occur.

These articles and videos have been vetted by my EE contacts around the country, so I'm confident this is how it all works. It only takes 30 volts and 30 mA of current to put your heart into fibrillation, so don't accept ANY shocks from your RV or appliances. Unplug immediately until you can determine the cause of the open grounding and current leakage. You can save your own life as well as the life of a family member or friends.

You may contact me directly at mike@noshockzone.org for any clarification.

Mike Sokol
mike@noshockzone.org
www.noshockzone.org

time2roll
Nomad
Nomad

deweysmith5
Explorer
Explorer
Actually, I check mine using and ungrounded extension every spring just to be sure.
2016 Cougar xlite 27rks
2015 Duramax Z71 Silverado
The Wife, The Lab, and sometimes a grandkid or two

tenbear
Explorer
Explorer
Wayne Dohnal wrote:
I agree there could be a further problem with the OP's rig, but I don't understand why this one should be singled out. Any ungrounded modern RV will have a "hot" chassis when not properly grounded, unless it has an independent earth ground. There's no more probability of this one having a further problem than your own or mine having a problem. In fact, I'd be suspicious of an ungrounded rig that doesn't have a "hot" skin. That could indicate a neutral-ground bond, and if plugged into a reversed polarity source it would be a hard-core life-threatening hazard.

I was thinking the same thing. How many of us that have always used 3 wire cords have checked for hidden problems?
Class C, 2004/5 Four Winds Dutchman Express 28A, Chevy chassis
2010 Subaru Impreza Sedan
Camped in 45 states, 7 Provinces and 1 Territory

Wayne_Dohnal
Explorer
Explorer
I agree there could be a further problem with the OP's rig, but I don't understand why this one should be singled out. Any ungrounded modern RV will have a "hot" chassis when not properly grounded, unless it has an independent earth ground. There's no more probability of this one having a further problem than your own or mine having a problem. In fact, I'd be suspicious of an ungrounded rig that doesn't have a "hot" skin. That could indicate a neutral-ground bond, and if plugged into a reversed polarity source it would be a hard-core life-threatening hazard.
2009 Fleetwood Icon 24A
Honda Fit dinghy with US Gear brake system
LinkPro battery monitor - EU2000i generator

deweysmith5
Explorer
Explorer
I agree with smkettner that the issue may not be resolved. I believe like many others here that further testing is required to be sure that it is only transient voltages and not a definite problem.
2016 Cougar xlite 27rks
2015 Duramax Z71 Silverado
The Wife, The Lab, and sometimes a grandkid or two

tenbear
Explorer
Explorer
smkettner wrote:
Harvard wrote:
smkettner wrote:
I still recommend a simple outlet tester to verify polarity.
Simple tool to keep handy in the toolbox.


Yes, if the OP had used an oulet tester downstream of the open ground he would have been made aware of a problem. On the other hand had an outlet tester been used ONLY at the pedestal one may not have been any the wiser.

The problem is a tool may only be as good as the experience level of the user.


I am not convinced the issue is resolved.

This is the tester that smk is referring to. Its a good tool to have with you and check the circuit in the RV when you plug in. Just plug it into an outlet in the RV.
Class C, 2004/5 Four Winds Dutchman Express 28A, Chevy chassis
2010 Subaru Impreza Sedan
Camped in 45 states, 7 Provinces and 1 Territory

time2roll
Nomad
Nomad
Harvard wrote:
smkettner wrote:
I still recommend a simple outlet tester to verify polarity.
Simple tool to keep handy in the toolbox.


Yes, if the OP had used an oulet tester downstream of the open ground he would have been made aware of a problem. On the other hand had an outlet tester been used ONLY at the pedestal one may not have been any the wiser.

The problem is a tool may only be as good as the experience level of the user.


I am not convinced the issue is resolved.

vermilye
Explorer
Explorer
Another useful tool is an inexpensive non-contact tester (Harbor Freight) or (Fluke) for those that prefer a brand name. While is does not provide absolute "proof" of conditions, if it lights (chirps or buzzes) when held to the chassis of the RV, further investigation is in order. Also useful for checking reverse polarity, open circuits, even can sometimes be used to find a break in a wire. A handy gadget!

Harvard
Explorer
Explorer
smkettner wrote:
I still recommend a simple outlet tester to verify polarity.
Simple tool to keep handy in the toolbox.


Yes, if the OP had used an oulet tester downstream of the open ground he would have been made aware of a problem. On the other hand had an outlet tester been used ONLY at the pedestal one may not have been any the wiser.

The problem is a tool may only be as good as the experience level of the user.

time2roll
Nomad
Nomad
I still recommend a simple outlet tester to verify polarity.
Simple tool to keep handy in the toolbox.

Wayne_Dohnal
Explorer
Explorer
vermilye wrote:
While I agree that most RVs will "float" without the ground connection, the problem is it is difficult for the average user to tell whether the tingle they feel is the normal "float" or a fault that could cause a dangerous shock hazard. The importance of a good ground connection cannot be over emphasized.
Absolutely agree, and thanks for adding that. Even though it's "normal" for an ungrounded RV to "float", it's a totally unacceptable situation because the ground is the last line of defense when there is an electrical fault that IS a real hazard. On a purely technical basis when the RV tingles, it's usually that the only reason is the lack of a ground connection, and the tingle is probably non-hazardous. But it could be a genuine hazardous situation and should be always treated as such. The RV should not be used with AC power until it is fixed. No exceptions. I also recommend that any RV be periodically plugged into a GFCI outlet which will detect many common electrical faults that otherwise don't show themselves. This issue comes up often and there's almost always a set of incorrect diagnoses posted. Too bad there's not a good sticky for it.
2009 Fleetwood Icon 24A
Honda Fit dinghy with US Gear brake system
LinkPro battery monitor - EU2000i generator