Getting shock off trailer

[Ricoh]

Set the trailer up on the weekend and plugged it into the 30 amp at our site. Surge protector did it's thing and delayed while checking power. Finally clicked on and energized the trailer. Every time I touch the aluminum on the slam doors etc I get a shock. What should I be looking at? It's a 2011 Bighorn 3185.

Thanks Rick

 

[Bob&Patty]

You could have a bad ground circuit in the trailer or at the pedistal.

 

[dbbls59]

More than likely an open ground at the pedestal.

 

[Invizatu]

Wouldn't this be life threatening if say you were barefoot, standing in wet grass? I am somewhat fearful of something I can't see and could kill me!

Good example of why an ems is a better / safer component than just a surge guard. (If the issue is in the pedestal)

Just curious, is there any reason you couldn't run a grounding cable from the frame to the ground? Would not correct the issue, but maybe save a life?

 

[pegmikef]

Is that a 50 Amp service hooked into a 30 Amp outlet? If so, make sure the ground is good in whatever you are using to convert the plug from 50 amp to 30 amp.

 

[wdk450]

Gang:
After a recent thread concerning the ground-neutral generator controversy, I did an internet search and came up with this 30 amp, in-line, weather resistant GFCI for about $130, free shipping. It comes with pigtail wires, get your own RV 30 amp plug and inline receptacle and wire them in. Similar 50 amp GFCI's were just too expensive. Here's the link: http://www.zorotools.com/g/00053488/k-G2167864/

 

[donr827]

http://www.noshockzone.org/rv-electrical-safety-surge-strips/ Try this web site. Good information for rv owners.
Don

 

[cookie]

What are you using for surge protection?
The right will tell you if you have an open ground.
If yours is supposed to, contact the manufacturer.

Peace
Dave

 

[brianharrison]

Is your surge protector a full Power Management system ? May be if there was a delay till energised - if so it should check for open ground at pedestal.

It sounds like something else is going on as well - If you umplug shore power do you still get shocked? - ie run on battery?

I would check the grounds on the battery - certainly check to make sure they are tight and not corroded. - Next would be a check on the main ground bar - usually near the battery on the frame - follow the battery ground wire back. Make sure they are all tight and no discoloration.

Unplug the shore power when working on electrical.

Brian

 

[Ricoh]

I have a Surge Guard 50 amp protector. Will have to check into it further next weekend.

Rick

 

[danemayer]

Rick,

This is very dangerous and I would recommend that you disconnect from shore power until you figure out what's wrong. In addition, a non-contact voltage tester from Home Depot or other hardware store will let you check for voltage without actually touching the trailer. A good one is about $20. Skip the $7 variety.

If the trailer skin is electrified, there are most likely TWO problems. Something in the trailer has a short circuit, AND you're missing a ground path. Because of the missing ground, the electricity that normally would be routed through the ground connection instead is electrifying the trailer skin. Then when you touch the skin, you're providing a better path to ground. You could be seriously injured or worse.

You need to verify the pedestal and the cable coming into the RV to make sure everything is wired correctly. I would expect you'll likely find the missing ground at one of these two points. Under OUTLET TESTING at [url]http://www.myrv.us/electric/ [/URL]you'll find wiring diagrams for testing 50Amp and 30Amp service.

Once you find and fix the missing ground, you'll still need someone to run down the short circuit that's leaking voltage.

Please circle back around to let us know what you find.

 

[jmsokol]

I'm Mike Sokol, the author of the NoShockZone article mentioned in this thread. Please see my article at http://www.noshockzone.org/rv-electrical-safety-part-iv-–-hot-skin/ about how to use a Non-Contact Voltage Tester for check for a hot skin condition. Yes, you most likely have a broken ground wire between the Surge/Voltage protector and the trailer's safety ground bonding point. And this is a VERY DANGEROUS condition that could kill you or a loved one, so disconnect immediately until you get the problem sorted out.

But there's also a very dangerous outlet condition I've deemed an RPBG (Reverse Polarity Bootleg Ground) which is a mis-wiring condition that can occur when old "ungrounded" outlets are upgraded to grounded outlets. If the electrician takes a shortcut and doesn't run a new ground wire, they can cheat and add a jumper between the ground and neutral screw. If the hot and neutral wires are also accidentally reversed in the old wiring, then the body of the RV or appliance plugged into this outlet will be energized to a full 120-volts, even though it appears to operate normally otherwise. See the article I wrote for Gary Bunzer (the RV Doctor) at http://www.rvdoctor.com/2001/07/friends-of-gary-mike.html.

Note that you CANNOT detect an RPBG outlet using a 3-light outlet tester, a voltmeter between H-N, H-G and N-G, nor even with a $300 Ground Loop Tester such as a SureTest Analyzer. Progressive Industries has duplicated my RPBG experiments at www.youtube.com/noshockzone and concluded that NONE of their products will recognize or disconnect your RV from an RPBG outlet. The simplest way to detect an RPBG outlet is by using a Non Contact Voltage Tester as I've indicated above.

Please contact me directly if you have any questions on this test procedure.

FYI: Here's a picture of how an RPBG is mis-wired, for those who want to follow the circuit.

 

[jmsokol]

Just curious, is there any reason you couldn't run a grounding cable from the frame to the ground? Would not correct the issue, but maybe save a life?

Actually, the earth itself is a pretty poor "ground", with a typical 8 foot ground rod measuring as much as 100 ohms, and still legal according to code. The safety ground wire in the pedestal outlet must be connected back to the service panel's Neutral/Ground/Earth bonding point, which creates something we engineers think of as a "ground plane". That's the only thing that will carry sufficient fault current to actually trip a 20 or 30 amp circuit breaker. The ground rod is there primarily as a lightning deterrent since it will keep your local "ground plane" very close to earth potential. I've seen ground rods damaged by lighting which allowed the entire ground system of a building to float above earth ground by 40 volts or so, which spikes in the 200 volt range when there was lightning strikes in the clouds above them. Very scary stuff as this condition can create side-strikes inside your various electrical appliances.

So know that individual ground rods and RV jack pads on the ground will do NOTHING to actually "ground" your trailer. It needs to have a solid low-resistance connection from its frame to the sub-panel via all the safety ground wiring. See the graphic below for my new ground-fault impedance test I'm experimenting with. Should be very simple for anybody to build and use to help find those pesky open grounds.

 

[Ricoh]

Mike

I went back up and unplugged my trailer. Owner was not there so I will send him an email. What should I ask him to check on his side before I start at checking my trailer. My son works for hydro(underground cableman) so I will get him to bring up some testing equipment on the weekend and get this straightened out.

Thanks

Rick

 

[jmsokol]

Mike

I went back up and unplugged my trailer. Owner was not there so I will send him an email. What should I ask him to check on his side before I start at checking my trailer. My son works for hydro(underground cableman) so I will get him to bring up some testing equipment on the weekend and get this straightened out.

Thanks

Rick

He first needs to confirm that the pedestal outlet has both proper polarity as well as a properly "earthed" ground. Have him watch these videos at http://www.youtube.com/noshockzone which demonstrates how to use a NCVT (Non Contact Voltage Tester) to check for absolute outlet polarity. If it lights up next to the ground contact (round hole) then you either have a floated ground or an RPBG with a hard ground-to-hot connection. Very dangerous and not easy to detect.

He can also put a short ground rod in the earth (piece of re-bar in wet soil) and test from earth-ground to each outlet contact. He should check for relative outlet voltages using the diagrams I drew here: http://www.noshockzone.org/rv-electrical-safety-part-iii-–-outlets/ The most important thing to confirm is that the voltage between the temporary ground rod to the ground contact in the power outlet should measure less than a volt or two, ideally close to zero volts.

He should also measure the resistance between the frame of the RV and the ground pin on your RV's shore power plug. Make sure it's disconnected from AC power first, of course. It should measure very close to zero ohms, certainly under 1 ohms.

Please let me know what he finds out. And he may contact me with any questions.

 

[evolvingpowercat]

If your protection device is the 30 Amp TRC Surge Guard with the 128 second delay which is there to protect your plugs from arcing and getting destroyed when you plug into the pedestal, and to protect your roof top air conditioners from short interruptions in AC power giving the AC coolant pressures time to normalize so the compressor can restart without damage, then...

It will connect AC to your RV even if there is a hazardous voltage i.e. "hot skin" on your trailer, it will NOT connect only when there is over-voltage or under-voltage. There is a warning light labeled "caution when flashing" that will warn you that there is current flowing on the ground wire thru the TRC Surge Guard which should not happen UNLESS something is flawed in your RV. The 50 Amp model TRC Surge Guard will actually open the power to the RV if it sense current on the ground wire. The 30 Amp model will just light the light but not open the Hot and Neutral wires.

I hope you will get a professional to check out your RV and/or the pedestal you are plugged into if this has never happened before you used this particular pedestal in this particular RV park. IT IS NEVER NORMAL TO GET A SHOCK WHEN STANDING ON THE GROUND AND TOUCHING YOUR RV. THIS COULD KILL SOMEONE WHO IS NOT WEARING SHOES OR PERHAPS EVEN WITH SHOES ON IN WET CONDITIONS.

 

[jmsokol]

IT IS NEVER NORMAL TO GET A SHOCK WHEN STANDING ON THE GROUND AND TOUCHING YOUR RV. THIS COULD KILL SOMEONE WHO IS NOT WEARING SHOES OR PERHAPS EVEN WITH SHOES ON IN WET CONDITIONS.

You're correct on all your points... But sadly, many RV parks don't have a certified RV technician on call, so they just move you to another pedestal and leave the mis-wired one for the next unlucky person to find. However, I couldn't live with myself if I walked away from a dangerous outlet, and the next person in the campsite was injured or killed. So stick with this until you find out the cause. Typically it will be a pedestal with a broken ground or RPBG outlet, or many times it's an inexpensive "dog-bone" adapter with an open internal ground wire. In any event, Evo-Cat is 100% correct... You should NEVER feel any sort of tingle while touching your RV under any circumstance. If you do, that's a warning that your next shock could be fatal, so don't risk it. Just last year an 18 year old boy was killed when he stepped into his parent's RV trailer in the backyard while barefoot in the wet grass. The parents had been feeling shocks all week, and simply wrapped the door handle with electrical tape. (NOT the correct fix). When he stepped onto the metal step and wet grass at the same time in his bare feet, it killed him on the spot. I suspect it was caused by an RPBG outlet in the garage where they plugged in the RV. What a tragedy.

 

[porthole]

Just curious, is there any reason you couldn't run a grounding cable from the frame to the ground? Would not correct the issue, but maybe save a life?

The main reason not to do is because the issue is still dangerous and doing this will lend to a false sense of security. and not fix the problem.

 

[JohnDar]

Unless I'm mistaken, simply running a grounding cable to the dirt under the trailer is not sufficient. Earth grounds require a certain depth in the right soil conditions to be effective. And the resistance has to be brought to less than 25 ohms for it to be effective. I seem to recall this from bonding/grounding exercises during HazMat Tech training.

 

[jmsokol]

Ys, even a perfect ground rod won't actually "ground" your RV. Those ground rods are really for lightning protection. As I've noted before, your RV's safety ground wire must be connected back to the Neutral/Ground/Earth bonding point at the electrical service panel to carry any significant fault current. As far as ground rod impedance, according to National Electrical Code a single ground rod that has less than 100 ohms impedance is all that's required. But if it exhibits MORE than 100 ohms impedance, a second ground rod is required.

Only "electronic" grounds for sensitive measuring equipment require a ground rod impedance of 25 ohms or less. Simple math shows you that 120 volts into a ground rod measuring 100 ohms only pulls 1.2 amperes from the line, certainly not enough to trip a 20 or 30 amp circuit breaker, but enough to trip any GFCI. Unfortunately, GFCI's are not required on any 30 amp RV pedestal outlets, but some 20 amp outlets will have a GFCI. However, many RV owners simply use a 30 to 20 amp adapter to get around the GFCI tripping issues, which are probably trying to save your life.

Ground loop fault impedance is another number, requiring no more than 1 ohm impedance back to the service panel. So math shows you that 120 volts across a 1 ohm load will attempt to draw 120 amps of current, certainly enough to trip any 20, 30, or 50 amp circuit breaker.