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Author Topic: HALP! Getting electrical shocked from bus 110V electricity shocking shock  (Read 7042 times)
Len Silva
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« Reply #30 on: January 14, 2013, 11:36:14 AM »

There should be NO leakage with the possible exception of capacitors as mentioned.  You should be able to measure with an ohmmeter between the neutral and ground on the main plug and get infinity.  Between hot and ground you may see a small kick in the meter (analog) as the capacitors charge up but it should also rise to infinity. Only between hot and neutral should you get a resistance reading at all, that is measuring across the various loads that may be connected.

I prefer an older analog meter for these tests but a digital will work.
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« Reply #31 on: January 18, 2013, 04:46:40 PM »

Your problem could be totally unrelated to your electrical system, other than needing to have the ground pin connected. 
Try to follow this:  every Labor Day I set up a food trailer in the park for the American Legion.  We have about a 30 amp supply directly out of the distribution box.  The trailer was wired by me, so I know it is all correct. (no attitude with that statement).  As other vendors started hooking into local outlets for coffee and hot dog machines, one of our members touched the trailer and got a shock. (he's ok) I went through everything I could possibly think of and then ran an idea by the local electrician.  As more people were connecting in, the voltage would shift on one leg to 140 volts and the other leg would go to about 70 or 80. We also tried adding a ground rod and it do not help.  My suspicion was correct, the neutral to the main distribution box was weak and our electrical system was completing the circuit to everybody elses equipment via the ground.  We ran a temporary neutral for the weekend and all was well.
On another occaision, I had a co-worker phone me that her son was getting shocked standing in the garage touching the rail for the overhead door. He was in bare feet.  I determined that the garage neutral was bad and needed to be replaced.  It was at this time in my life that I also discovered that CONCRETE IS CONDUCTIVE.  I was able to touch one lead of my meter to the rail and the other to the concrete and I read over 90 volts.
When you first set up camp, take a meter with you and stick one end in the ground and the other end on the frame of your bus.  Look for voltage.  If any is present, disconnect your shore line before it kills you!!!
Happy hunting.
Ed
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« Reply #32 on: November 08, 2013, 06:01:36 AM »

For what it's worth, there is no approved continuous leakage to ground in AC appliances. Televisions and inverters sometimes have small value condensers connected to ground that will pass a tiny current. GFCIs are designed to trip if there is an unbalance in the current in the black and white leads. This is so that they will trip even if the current is running to earth.

I'm Mike Sokol, the writer of the Church Woodbury article quoted at the top of this thread, and author of the www.NoShockZone.org website about RV electrical safety. I'm getting ready to write some new articles about RV hot skin conditions, and researching misconceptions about how they occur. So much more on this later, but here's the basics.

1) For a hot-skin condition to occur you first need an open or high resistance safety ground connection between the chassis/skin of your RV and the Ground-Neutral-Earth bonding point back at the main electrical service panel. Most of the time it's caused by an open ground wire connection inside a dog-bone or pig-tail adapter, but can also occur from a worn or damaged pedestal outlet, mis-wired home receptacle, or even a broken or non-existent wire in a power feed. I've found RV's with loose grounding screws in their own circuit breaker panel, and at least one of them with a broken ground lug on the back of the shore power twist-lock connector. This safety ground needs to have a very low impedance path all the way back to the entrance service panel (less than 1 ohm total) to meet electrical code standards. And no, a ground rod driven into the earth next to your RV will do little or nothing to actually "ground" your RV since a ground rod can have up to 100 ohms impedance to earth and still be code compliant. The ground rod's job is actually to drain away lightning strike currents and keep the local grid's ground voltage close to earth potential.

2) You need a source of leakage current to electrify the skin of the RV. Now I want to correct the statement made in the quote above. Virtually ALL electrical appliances plugged into a 120-volt outlet will have leakage currents to their own chassis. And that amount of current is regulated by UL and the NEC. An appliance without a grounded plug is limited to a maximum leakage current of 0.75 mA (milli-amperes). You'll find that "ungrounded" appliances such as a crock-pot, iPhone charger, or laptop computer will normally develop a "hot-skin" potential around 60 volts even when everything is operating correctly. But because the current is limited by UL standards to less to 0.75 mA, you'll never feel a shock. Just over 1 mA of 120-volts, 60 Hz AC is the lower threshold of feeling a shock, which is certainly not dangerous. However, appliances with a grounded plug can have a maximum of 3.5 mA of leakage current between the line and chassis and still be within UL guidelines. Normally that 3.5 mA of leakage current is drained away harmlessly by the safety ground path of your RV. But if your RV's safety ground path is compromised, then there's nothing to drain away that leakage current and a hot-skin voltage is the result.

3) Those hot-skin voltages come in two flavors, high-current and low-current. The low-current hot-skin condition can be caused by a single appliance inside your RV with normal leakage currents. This can be a microwave oven, RV battery inverter, refrigerator, television set, or even a computer with a grounded power cord plugged into your RV's 120-volt system. Also note that these appliance leakage currents are additive, so 2 or 3 mA of leakage from your microwave can add to the 2 or 3 mA of leakage from a MOV surge strip (yes, they leak current to the safety ground as well). So it's entirely possible to generate over 5 mA of leakage current to ground which will trip a GFCI 20-amp receptacle on your campsite pedestal.

4) A high-current hot-skin condition is typically caused by a wire inside the walls of your RV being drilled through by a screw, or pinched by a box cover, or even worn through insulation that's hanging on a metal crossbeam. High-current hot skins can easily provide dozens of amps of current, so if you touch an RV with a high-current hot-skin, your body's 1,000 ohm resistance (damp hand to hand or hand to foot) can cause up to 120 mA of shock current to flow through your chest cavity. Note that only 10 mA of 60 Hz current is dangerous to a person with a weak heart and is very painful, 20 mA will cause your muscles to seize to the point where you can't let go of an electrified object, and 30 mA of current through your chest cavity for a few seconds is nearly always fatal without immediate CPR and defibrillation.  

So, it's completely possible to trip a GFCI at a 20-amp pedestal outlet and to have nothing specifically wrong with an RV electrical system. It's also possible to generate a 120-volt hot-skin condition from a broken safety ground wire that results from these same high-impedance leakage currents from several of your RV appliances, all of which are operating within UL leakage limits.

A ground rod driven next to your RV can drain away a high-impedance (low-current) hot-skin voltage, but will do NOTHING to stop a low-impedance (high current) hot-skin voltage. And putting your leveling jacks down on the dirt will do nothing to "ground" your RV, contrary to popular belief. And as little as 30-volts AC across wet hands can induce 30 mA of current across your heart and be deadly.  

The takeaway is that your should NEVER feel any type of shock from any appliance or RV. If you do feel a shock, then shut it down and unplug immediately and get it checked by a licensed electrician or technician. However, note that there's a lot of electricians and technicians who don't seem to understand what causes shock conditions, so if there's any doubt, measure the hot-skin voltage yourself. Here's an article I wrote on how to test for hot-skin voltages using a simple Non Contact Voltage Tester (NCVT) which you can purchase online or at any big-box store for less than $25 (and many times less than $15). See http://www.noshockzone.org/rv-electrical-safety-part-iv--hot-skin/ for the article.

Please let me know if that makes sense and contact me at mike@noshockzone.org with any questions.

Mike Sokol
www.NoShockZone.org
mike@noshockzone.org
« Last Edit: November 08, 2013, 03:52:29 PM by jmsokol » Logged
Bob & Tracey
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« Reply #33 on: November 08, 2013, 06:25:33 AM »

I had this problem and in my case it was caused by the neutral and ground being connected in the breaker panel in the bus.
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Bob & Tracey Rice    Cedar Grove, Wi. (40mi. Milwaukee)

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« Reply #34 on: November 08, 2013, 09:22:13 AM »

I had this problem and in my case it was caused by the neutral and ground being connected in the breaker panel in the bus.


Connecting the neutral and ground wires together in your RV breaker panel is a violation of both NEC and RVIA wiring code. They MUST remain separated, only to be bonded together at the incoming electrical service panel, or by your portable or on-board generator. The same goes for subpanels at a campground (the pedestals). There can be no bond between the neutral and ground wires in the pedestal, and code doesn't allow a local ground rod to take the place of a low-impedance (less than 1 ohm) safety ground wire that's run back to the incoming service panel. The NEC does not "disallow" having additional "local" ground rods, but without a connection back to the service panel they can't protect you from a low-impedance (high current) ground fault. The ground-rod confusion comes from the fact that a local ground-rod can drain away high-impedance (low current) shock voltage caused by normal RV appliance leakage (as I've detailed above), but will do nothing to protect you from a high-current hot-skin condition.

Mike Sokol
www.NoShockZone.org
« Last Edit: November 08, 2013, 09:37:10 AM by jmsokol » Logged
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« Reply #35 on: November 08, 2013, 12:10:24 PM »

Mike,

Don't yell at me, I didn't do it.  Grin
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Bob & Tracey Rice    Cedar Grove, Wi. (40mi. Milwaukee)

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« Reply #36 on: November 08, 2013, 12:23:02 PM »

Mike,

Don't yell at me, I didn't do it.  Grin

I'm not yelling (yet).  Roll Eyes

I can see a problem with bus conversions is that many hands have been in the stewpot before you ever got into the kitchen. So dangerous miswiring conditions could be in place years before you acquire a bus or convert one. I'll do what I can to help keep you guys safe from electrical dangers.

Mike Sokol
www.NoShockZone.org 
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« Reply #37 on: November 08, 2013, 11:34:46 PM »

JMSOKOL- Welcome to the board - we have somewhat lost Sean Welsh due to his transfer to a trawler (boat) - hopefully you will be able to take over where he left off - check the archives to see what I'm referencing - Are you sure you're not Sean using a pseudonym  Huh

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« Reply #38 on: November 09, 2013, 01:16:50 PM »

JMSOKOL- Welcome to the board - we have somewhat lost Sean Welsh due to his transfer to a trawler (boat) - hopefully you will be able to take over where he left off - check the archives to see what I'm referencing - Are you sure you're not Sean using a pseudonym  Huh

Hmmmm..... Not sure who this Sean Welsh guy is, but I assume from his postings that he's an electrical guru of sorts. But no, I'm not Sean working for the CIA in disguise (but even if I were, I couldn't tell you). I'm just a Mechanical/Electrical/Audio engineer and received my Master Electrician License in 1978.

However, I'm not a bus guy, or even a camping guy. I did in fact camp across 40 states and half of Canada back in the 60's and 70's with my parents. But now I'm a nationwide seminar instructor who drives 50,000 miles a year teaching music mixing and sound production. But I've been interested in electrical safety since the 70's, and got really interested in tour bus electrical safety when some of my pro-sound buddies doing major music tours complained about getting shocked. Now, a tour bus for a rock star is essentially what you guys have, just on a more modest budget. But the same electrical shock hazards exist for ANY type of RV plugged into a shore power connection.

That's why I started www.NoShockZone.org. I found a lot of confusion about RV wiring and electrical shock hazards, even from some of the so-called "experts". In fact, I've pioneered the use of NCVT (Non Contact Voltage Testers) for finding RV Hot-Skin conditions. See below for a video where I hot-skin electrify a 40-ft RV and test for the condition with a Fluke VoltAlert NCVT.  

I've also discovered and named an outlet miswiring condition that much of the electrical industry seems to misunderstand or ignore. Check out my article at EC&M magazine and The RV Doctor's site about something I call an RPBG (Reverse Polarity Bootleg Ground) mis-wiring condition that will create a hot-skin condition on ANY RV or Bus plugged into it, and there's no surge protector or voltage monitor on the market that will warn you or disconnect you from it. http://www.rvdoctor.com/2001/07/friends-of-gary-mike.html and  http://ecmweb.com/contractor/failures-outlet-testing-exposed However, a $20 NCVT will easily find an RPBG mis-wired outlet and identify a hot-skin condition on your bus that results from plugging your shore power line into one. I'm now trying to identify just how my RPBG mis-wired outlets exist in the country, but it's certainly something to watch out for when plugging into "garage outlet" power while visiting someone in their driveway.

So while I'm not a "Bus-Nut" or even a camping guy, I'm totally into bus wiring and electrical safety for consumers. Please give me a shout-out if you see any threads on this forum that could use my help. My direct email is mike@noshockzone.org

Mike Sokol
www.NoShockZone.org

« Last Edit: November 10, 2013, 06:03:29 AM by jmsokol » Logged
Seangie
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« Reply #39 on: November 09, 2013, 02:29:17 PM »

Mike,

Welcome to the board and thanks so much for taking the time to share good information.  Watch out though.  If you hang around these parts long enough you might get a touch of busitetis.

-Sean


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« Reply #40 on: November 09, 2013, 02:50:08 PM »

If you hang around these parts long enough you might get a touch of busitetis.

I admit to having looked at busses in a lustful way. Is that the first symptom?

Mike
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« Reply #41 on: November 09, 2013, 07:40:02 PM »

That's how it starts, Mike! Wink Grin
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Mark Morgan    near Brandon, Manitoba, Canada
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« Reply #42 on: November 09, 2013, 08:04:56 PM »

   That's how it starts, Mike! Wink Grin 

     Yeah, if you ever catch yourself saying "That looks good!", "I can do better than that", "it won't take long", and "that won't cost much" within a 30 minute period, have someone lock you in a small room and throw away the key!!!
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« Reply #43 on: November 09, 2013, 09:25:00 PM »

Thank you for sharing your expertise.  A lot of us guys need it.
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« Reply #44 on: November 10, 2013, 05:54:09 AM »

Constructive info/help is always the goal here!!  Death trap--I wouldn't step foot in that thing type statements don't help a person correct a problem or do it correct when _I_ or someone else makes a mistake.  I have just disassembled a pro conversion because of a fire that I would consider sub standard. Everyone here goal is to do the best with the most correct info available.  That is why I only share mostly my mistakes!!  Take this for what it is worth.    Lots of variables here that are not in sticks and staples that the over the hill gang has been there and done that wrong....     Will be asking questions because I'm electric challenged but just remember keep them simple  I don't have the diploma you do.       Bob
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