Electrical Shock when touching RV

[Robert Green]

2002 Patriot Thunder. Getting shocked when I touch the coach and the rig is connected to shore power. Does not occur when running of generator.

Found this very interesting website noshockzone.org. This man is passionate about informing and educating RVers as to the danger of ignoring "hot chassis".

http://www.noshockzone.org/are-little-shocks-ok/#comments

Per this site, the author focuses on a proper RV safety ground back to the service panel. He writes:

"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."

"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."

We became aware of the condition from the mechanic who installed the new batteries and did some other work.  When I brought it home, I wired a 50 amp service panel and connected the rig.  Same issue and I know my panel is wired correctly. 

I believe my next action is to address the extension cord.  It sits in a hopper insides the engine compartment and over the muffler.  I am wondering if high temps have compromised the cord.

Anyone delt with this symptom?

[Fred Brooks]

          Hi Bob,

       According to RVIA and NEC code, because the coach is "NOT" grounded by nature and it is sitting on rubber tires, It gets its ground thru the neutral white wire at the pedistal. The green wire is the safety back-up ground in case you have a failure with any device that fails internally and creates a short it has a path to ground so you don't get shocked. (same as in a house) The issue that a motorhome is faced with is the fact that it is mobile and subject to vibration which can compromise the electrical system.
      If you were to "loose the neutral" then the power coming in on the red wire and the black wire at the pedistal have no path back. The electricity will normally seek the weakest link to "make" a path back to ground. This is why we hear all the horror stories about being in an RV park and something goes wrong and all of a sudden everything gets "fried" ie: TV's, microwave, air conditioners, refer, inverter and the like. This is why we buy a surge protecter to keep this and other situations from attacking the coach.
      If the skin on the coach is "hot" it means somewhere a 110volt wire is connected or touching the metal sheeting that covers the outside of the vehicle. This applies more to older units or travel trailers who have aluminum skins. Our coaches have fibreglas skins which will not conduct electricity.
     I have personally been shocked by grabbing a roof ladder while standing in a puddle of water. It almost killed me beacause I could not let go. I finally realized what was happening and with my free arm smacked my clenched arm loose of my grip. It turned out that one of the mounting screws thru the standoff of the ladder had pierced a romex wire behind the rear cap.
     If you suspect that your coach exterior is "hot", Use a meter to check ac voltage between a known ground at the pedistal and the part of the exterior you suspect. If it is more that a couple of volts, you may have an issue.
Another area that causes issues is power cord reels. Over time, the moving contacts in the reel can wear or loose there ability to stay in contact with the power source. If you are not comfortable performing these checks, seek professional help. Hope this helps, Fred

[Robert Green]

Fred
Thank you.  Excellent input and advice.  My outlet is wired exactly as you've noted. 

I believe I'll pull the shore power cord as a start and check the condition of the cord (continuity) and the contacts. 

To your point, the skin is not hot, but the metal frames around the basement doors, and the other metal structures can deliver a good sting.  The gold wedding band really does do a wonderful job of conducting electricity!

Thanks again for the help.  Greatly appreciated. 

[Fred Brooks]

                    Hi Robert,

   You answered my next question by stating that the structure around the compartments are "hot". Our next objective is to "divide and conquer" as to the cause. Lets start by turning off the inverter/ charger at the the main panel circuit breaker and test Another test after that would be to turn off each circuit breaker one at a time and test. Do these tests after the continuity or ohm test on the power reel. Things that move are subject to failure, so check the shore cord at the transfer relay on both hots, neutral and the green wire ground. Let me know and we will go from there.  Regards Fred