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View Full Version : Electrical SHOCK when hooked to external AC connection.


slateblue911
11-23-2009, 10:01 PM
I am experiencing an electrical shock when my 1971 Newell Coach is hooked to an external AC connection. This happens when the kids touch the exterior with no shoes on. UMMM. It doesn't hurt them but thier hair stands up on end. I am sure that it has to do with my ground wiring but I just want to get a second, third or more opinions on this before I go off and do something stupid and burn it to the ground. Please help if you can. I would like to keep it hooked up permanently while it is at the house.

I also am experiencing a problem when the AC is hooked up and I flip the switch for the electrical converter. Well it has knocked out two of my ceiling lights.

Obviously, I do not know what I am doing but I can say that I have not touched the breaker box or anything that leads to it. :)

prestadude
11-24-2009, 07:21 AM
I don't know if you have a 30 or 50 amp system, but it sounds like you have a bad neutral and the coach is not properly grounded, hence the electrical shock. I think this is serious enough that the problem should be fixed before using the coach again. It could be in the coach or in the power supply from the supply socket. When I bought my coach earlier this year, the paperwork included a handout on 120 volt coach electrical service from a seminar given at the January, 2003 Newell Rally in Palm Springs, California. I quote a few paragraphs from the handout that explains the issue in laymans terms (and boy am I a layman with electricity):

A 30-amp RV plug contains a 'hot' supply wire that brings electrical flow into the coach and a neutral output wire (also called a ground or common) that returns the flow to the power plant. If the 'hot" input wire breaks, the incoming power stops and you are without power. If the 'neutral' return wire breaks, the electrons continue flowing into the coach, with no place to go. Your RV is now 'filled' with electrons and becuase it sits on insulating rubber tires, the electrons just sit there looking for an easy pathway home.

The earth is a pretty good conductor and it is huge, so it makes a great return path for electrons. "Ground" in the power distribution grid is literally "the ground" that's all around you when you are walking outside. It is the dirt, rocks, groundwater, etc., of the earth. Because electrons are always seeking a path to ground it is important that you stay ouf of their path. For example, Joe Camper plugs his RV into an RV park pedestal having a faulty neutral and his RV becomes 'charged' with electrons with no place to go. The electrons just sit there like vultures waiting for the kill. Poor Joe returns to his coach after a late night rain shower, inserts the key into the door, and gets the shock of a lifetime.

To reduce deadly grounding accidents, the building code requires the addition of a safety wire and a grounded neutral. The safety wire is attached to a long rod driven deep into the ground. The neutral and safety wire in a residential service are bonded to the grounding rod in the home's main curcuit breaker panel. Because RV's sit on insulating tires, and most RVer's refuse to pound a metals rod deep into the ground every time they stop, both the safety wire and the neutral wire are kept separate until reaching the RV parks electrical system via your service cord. Once inside the park pedestal they are bonded together and attached to a grounding rod. This is called a floating neutral, and it places you at the mercy of the RV parks electrical system. If the RV park service pedestal has a faulty ground, then your coach has a faulty ground. If the service box is wired backwards, (reverse polarity) then your coach system will be backwards.
On my coach (2000) Newell has provided a warning light that indicates if the polarity is wrong. I cannot remember if there is a similar warning light indicating an ungrounded neutral. The same handout describes the procedure for checking a 50 amp park pedestal for proper wiring using a multi-meter.

As you face the [50 amp] receptacle at the campground pedestal, you'll see three vertical, flat slots. The outer (left and rigth vertical slots) are 120 VAC 'hot' outlets. The inner (center/lower) flat, vertical slot is the neutral. The round hole near the top is the ground.

Set the multi-meter for AC volts and go to the higher range (usually 750 volts). Put one probe in the left hot slot and one probe in the right hot slot. You should read about 240 VAC.

Next, move one 'hot' probe to the neutral (center) slot. You should read about 120 VAC. Move the hot probe to the other hot slot. You should again read about 120.

Next, move probe from neutral slot to round ground hold. You should again read about 120 VAC. Move probe from first hot slot to other hot slot and again should read about 120 VAC. The receptacle is OK.

slateblue911
11-24-2009, 02:21 PM
Thank you prestadude for your response. I would also like to thank James Tuckness too. Both of you have given me something to look for and a star tin diagnosing the problem. I will start with the house power and make sure that my ground is properly configured. If I remember correctly my house witing has the ground and operating neutral wired together. I may have to separate these to make this work or separate the ground to the Newell properly. Either way both of you have given me great information. I will post what I find once I have made the necessary checks and changes.

HoosierDaddy
11-24-2009, 02:56 PM
I have a simple test plug that I keep in the coach. My coach has a 115V receptacle in the power cord storage bay. I keep it plugged in there. As soon as I plug into a power source there are 3 lights on the test plug that light up in different configurations depending on the polarity and presence of a proper connection. These test plugs are available at any hardware store. It's primary function is to check proper wiring of a receptacle but I believe it would indicate an improper ground as well.

slateblue911
11-27-2009, 06:15 PM
I want to thank each of you for your responses. I found the problem and it has been corrected. It is extremely nice to know that this forum has members that are willing to help without any hesitation. Here is what I did after reading the responses and talking with James Tuckness.

First. I separated the ground from the neutral in my breaker box on the house. I only did this for my RV connection. When I plugged in the short adapter cable I still didn't have a ground. Well, it turns out that the adapter cable didn't have a ground lead in it. I put it aside. When I bought the Newell the previous owner had made a custom cable that was about 30 feet long. I pulled the ends apart on it and checked the pin outs on both ends. The appeared to be correct so I plugged it in and then checked the voltages at the coach end of the cable. All appeared to be correct. I plugged it in and checked all of the outlets and equipment in the coach. I then check ed the outside outlets. All seems to be fine. Next, I checked the outside body shell to the outside outlet. I got voltage across the plug but not across the ground prong. Finally I checked the voltage from the body shell to the ground at the house. Yes. This would be the steel rod going into the ground. No voltage across that connection.

Today, I am going to Home Depot to get the necessary supplies to make this wiring permanent outside my house.

I also want to say that no teenagers were harmed in the final check. LOL!