Are “Little” Shocks OK?

Aug 16th, 2013 | By | Category: RV Safety
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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,

“Shocking Blue”

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Dear Shock,

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

night_lightFYI: 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.

Bootleg Ground WiringThere’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.

RPBG with 3-light testerHowever, 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.

Mike Sokol
mike@noshockzone.org
No Shock Zone

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24 Comments to “Are “Little” Shocks OK?”

  1. Ray says:

    Thanks Mike for another great RV electrical safety article. I love how thorough and in depth they are.

  2. Tony Chastain says:

    Found the same thing in our 2003 Windsor PST. The issue is the plug is not grounded properly. On our coach the ground wire was barely within the plug, much less grounded well. In order to solve the problem we replaced our plug with a new one.
    Tony

  3. Baron says:

    That’s what I thought!
    My entire house gives off a little shock, even on things that don’t have a ground lead. The case on my laptop “buzzes” when I touch it.
    The short could be anywhere in our building, right?
    Which test should I try? We have 220V. I was thinking of starting at the line in to see if the neutral or ground is energized. I got that non-contact tester you recommended.
    Any thoughts?
    Thanks,
    Baron

    • Mike Sokol says:

      Where are you located? The USA is 120/240 volts, so I’m assuming you’re not in the states. But it does sound like you have a neutral that’s lost its bond to the ground rod. To know if your building neutral is floating you’ll need to test the voltage between the neutral and a metal ground you put in the earth. A big screwdriver in the earth will suffice. By running a wire from the screwdriver close to a receptacle you’ll be able to measure the actual voltage. But you really should get an electrician for do this test since there’s the possibility of lethal voltages between the screwdriver ground and the neutral. If you do find more than 2 or 3 voltage between the neutral and the earth, then there’s a bonding point that’s either corroded or disconnected. If you had a nearby lightning strike in the past, then that’s sufficient to melt to wire feeding the ground rod in some cases, leaving your local neutral to float above earth potential. I once measured 40 volts AC between neutral and earth potential which would give a tingle on a sunny day, but would spike above 200 volts DC when you saw lightning in the clouds. The actual function of the ground rod is to keep your neutral voltage close to earth potential. So if you’ve lost your neutral connection (bond) to the ground (earthing) rod, that could explain what’s happening.

      • Baron says:

        I’m in Korea. I’m BigBaron on Popuportal.com

        Can I ground to a metal water pipe? I’m on the tenth floor… Getting a screwdriver into the ground is going to take a bit of wire.

        • Mike Sokol says:

          Yes, a metal water pipe should suffice for an “earth” ground connection. As I understand it, Korean wiring is similar to USA wiring with a Hot, Neutral and Ground, except that Hot to Neutral potential measures 220-230 volts rather than 115 to 120 volts as in the USA.

          • William Anliker says:

            At least here in the states, it can only be a cold water pipe that can be used for a ground, because of the possibility that due to fibre-glas hot water heaters, you might not have continuity to the outside ground.
            And that is only for some things, the code does not allow another ground besides the one at the source of the power source

          • Mike Sokol says:

            My comment about the water pipe ground was not for USA wiring. I was only suggesting the metal water pipe as a test point for a reader in Korea, NOT as the actual safety ground rod. In America the safety ground rod must comply with local building and electrical codes.

  4. William Anliker says:

    You said: ” if your hands and feet are wet.”

    This infers that if they are dry you won’t get a shock. Electrical shock, is not always a hands to feet thing, it can be a hand , arm, head, neck, or any other part of your body, to any other part of your body.
    The worst shock I ever got in 50 years as an electrician, was from the edge of my neck, to my leg. Knocked me clear across the room.
    No wetness is necessary, and people need to know that.
    Also the danger of a shock in greatly increased by the path it takes, a foot to the same leg, is not as dangerous, as a path thru the chest/heart. Which is extremely dangerous.
    The only time wetness really comes into play, is if it decreases the resistance/impedance, of the entry or exit point of the electrical path.
    Under the same exact condition, a mans calloused hands, will not give as large as a shock as a women’s soft, moist skin will.
    bill

    • Mike Sokol says:

      My statement about your “hands and feet are wet” was used in the context of “feeling” low-voltage shocks from RVs. Of course, everyone has SOME moisture on their skin and will conduct SOME current. How much is the question. For instance, two years ago a teenage boy in Muncie, Indiana was electrocuted when he stepped into his family RV in the middle of the night with bare feet in wet grass. During the day everyone was receiving minor shocks while the lawn was dry even with bare feet, which prompted them to wrap the RV’s door handle with electrical tape as a solution. Of course, the combination of wet grass, bare feet, and metal steps caused him to be electrocuted (killed) in the middle of the night.

      Everyone needs to know to NEVER accept ANY shock from ANY appliance. If you feel any kind of tingle, then is wrong with the ground and it’s only a matter of time before the right set of circumstances kills someone.

  5. David Zdrill says:

    I was always one of those guys who just couldn’t “get it” when it came to anything electrical. Nothing anyone told me seemed to register. After reading your articles it is the first time I’m actually starting to understand. I appreciate your writing style and all the effort you put into these articles. Thanks for sharing your incredible knowledge base.

  6. Mike Sokol says:

    Thank you for the kind words. I’m a firm believer that everyone who wants to learn about electricity can do so, as long as the proper training material is utilized. Most texts about electricity are just too complicated to jump into without knowing how it all works to begin with. And knowing how electricity works can help keep you safe in an increasingly electrified world. Please pass these articles onto everyone one you know who shows an interest in electricity and electrical safety.

  7. George says:

    Ray referred me to this article and YouTube video. I bought one of those NC voltage testers and dang if it didn’t register a hot skin when we stayed at the Grand Sierra Resort casino RV park.
    Thanks for the article may have saved us some serious grief!

    G

  8. Erik says:

    Would a GFI outlet or breaker protect you from these hot skin conditions?

    • Mike Sokol says:

      Yes, but only if you’re plugged into a 20-amp outlet in a pedestal or home that’s GFCI protected. There are no GFCI protected circuit breakers on the 30 or 50 amp outlets on a pedestal. The RV’s internal GFCI breakers are downstream of this and may not trip from an external fault condition.

  9. Evan in Thailand says:

    Mike,

    First off, great article and web site. I am living for several years overseas here in Thailand (220V 50Hz). I’ve noticed a slight tingle from some electronic items attached to the power receptacle in my small house. Specifically, my small aluminum chassis computer gives off a very slight tingle. Also, any wire connected to the computer (USB, 3.5mm audio cable) seems to give a slight shock as well. Would this also be considered “hot-skin”?

    From your explanations above, would it be safe to assume that I’ve got a bootlegged connection of one sort or the other with some leakage coming up either the neutral or hot wires?

    They don’t exactly have much in the way of electrical codes in these parts, and even if they did, you’d be challenged to find someone who knew or cared enough to follow them.

    Evan

    • Mike Sokol says:

      Evan,

      Any shock you can feel would be considered a hot-skin condition, but without a standardized grounding system like we have in the USA, Canada, and the UK (among others), there may not be a lot you can do about it. However, you should at least measure the voltage between the piece of gear in question and something like a water pipe (if it’ metal) or a screwdriver in the ground. That would give you a hint as to what was happening. It may simply be that you have to take extra safety precautions such as not standing on a wet surface and contacting any gear, and possible installing your own GFCI via an extension cord. I’m curious as to your mains voltage there. Is it 120, 230, or something else?

      • Evan in Thailand says:

        Hi Mike, thanks for the response. I don’t have direct access to ground here due to my distance to the actual ground and lack of metal piping, however, when I measured the voltage (AC) between the 3.5mm audio cable and my tiled floor, it read ~90 volts.

        Over here in Thailand, I believe their mains are on a 220V 50Hz system.

  10. Glilbert says:

    Hello Mike. I would like to know if it is possible to perform polarity checking on receptacles that are in use. Such as at a facility or hospital where critical equipment is in use and cannot be unplugged. My theory is that I may be able to at least be able to tell hot, neutral, and ground with a non contact voltage detector. I would like to use the fluke FLK-1AC-A1-II for the testing, but is it sensitive enough? Or might I be able to slip it between the receptacle and the plug to touch the blades to get a reading? the tip looks thin and long enough to try that. I haven’t purchased a detector yet and would appreciate your input and opinion. Thanks, Gilbert

  11. dmyrick says:

    Do stabilizing jacks (connected to frame) offer any grounding protection in the case of a hot skin situation?

    • Mike Sokol says:

      No, not really. While jacks may provide a high impedance connection to the earth ground of a few thousand ohms, that’s not low enough to provide any protection. Remember that even a ground rod in the earth may have a 25 t0 100 ohm impedance, and even THAT’S not low enough for a real “Ground”. Code calls for less than 1 ohm impedance back to the service panel Ground-Neutral-Earth bond to be effective.

  12. Mike M says:

    Hi Mike
    My wife and I recently purchased a new Keystone passport 2400BH (our first trailer). Our first time using shore power I was shocked while using the outside shower. I went to disconnect the power and discovered that it had partially fallen out on its own causing a ground fault. I had connected a Camco power defender circuit analyser before the cable. The added weight hanging out from the receptacle made it easier to tilt out the ground, but kept it from disconnecting the hot and common terminals. A dangerous product in my opinion. In your article you mention current leaking from appliances to the frame. Are you saying it is normal to get hot skin without the ground (or did I just happen to reveal a short circuit in the trailer while my ground was tempoarirly disconnected)? I would think a short in the trailer should trip a breaker or blow a fuse which is not hasppening. With the ground in the trailer has no problems. And one more question…I have a GFCI circuit breaker for the camp pedestal now but currenty don’t have a way to power the trailer. When I hookup would the GFCI trip if there is a short in the trailer? Seems like it would. I’m trying to avoid an unessesary return to the dealer.
    Thanks for all your extremely helpful articles!!

    • Mike Sokol says:

      Yes, it’s perfectly normal to feel a shock from an RV without a solid Ground wire connection. Everything that plugs into an outlet leaks a little current to its chassis, and this is additive for all of the appliances. So most of the time this will only be a few mA (milli-amps). Since the average human can feel a shock at 1 mA, a broken ground will allow you to feel a non-deadly shock. The real danger is that without a ground wire you don’t know if there’s enough fault current to kill you.

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