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LarryMars · 12-08-2010, 04:54 PM

I have a 2004 Adventurer and am in an RV park. When we got here three weeks ago, when we turned on the 50A breaker, the plug-in Radioshack volt meter pegged high. I shut the power off and after a little while, the park got it back on and it looked fine.

Yesterday, things started popping and smoking. In the end, I have lost my converter/charger, microwave, sleep-number bed, a power-strip for my TV, etc, and two outlets no longer work.

The park electrician says it was nothing on their end, and that it had to be my motorhome. Is this possible? Can my motorhome cause all this stuff to blow all at once?

Triker56 · 12-08-2010, 05:44 PM

NO Your MH can't produce high volts.
Bad thing the park could blame the company that furnishes the power for it. Good Luck getting any money from them.

Little late now. But why didn't you have a surge protector. almost a must for a RV. They shut power off with under or over Volts present.

Check with your insurance company for help.

Mike Canter · 12-08-2010, 05:45 PM

For it to read high like that usually indicates that the neutral was lost. This could be the fault of the MH (but I doubt it), in the electrical box you plugged into or the whole campground. If nobody else in the campground had a problem then I would suspect the box you plugged into. The big question here would be if it was the box then how did it magically fix itself inless it was pitted or dirty contacts.

pk42 · 12-08-2010, 05:58 PM

I agree with Mike it sounds like you lost the nutral which would put an exesive voltage on you system,this could also be caused by a bad conection in your rv 50 amp cable....pk42

WSRG · 12-08-2010, 05:59 PM

If the neutral on the 50 amp plug becomes "open", you will get 220 volts into the motorhome. I've heard of situations where the neutral would go open with moderate to high current usage in the coach and cause an intermittant problem with the neutral circuit. This open neutral condition can be in the coach wiring or on the campground power post. It mostly occurs on the power post because of moisture in the power post box. I have only heard of one situation where the problem was in the coach.

Bill

RJay · 12-08-2010, 06:03 PM

Voltage swings from one live leg to the other is indicative of a bad neutral because the neutral is no longer the reference point. A way to check this in the future before you plug in is to measure the voltage at the pedestal between each live leg and the neutral. If the voltage is the same the neutral is good if the voltage is different perform the same test to ground. If the voltage readings to ground are the same suspect the neutral.

bigskymt · 12-08-2010, 06:34 PM

Im curious and hope someone will explain how an open neutral can cause a voltage surge. If phase 1 plus neutral feeds the microwave for instance, and phase 2 plus neutral feeds the power strip (for example) how do the two create 208/240?.....through their respective loads?
The two dead outlets might indicate a failed ground fault.

LarryMars · 12-08-2010, 07:52 PM

When things hardly ever happen, they usually happen to me when they do.
How would I test whether or not the ground on my motorhome is adequate?
I, too, would like a better explanation how L1 and L2 can show up on one 120VAC circuit. I think I have seen it happen, but I do not understand. The park electrician says it is impossible. Thanks to all for your great answers.
And, yes, I will invest in a surge protector. Would this protect against such an event?
Larry

Gary RVRoamer · 12-08-2010, 07:55 PM

Here is an explanation of the open neutral problem:

Main Neutral Open - Main Hot Open

And an example with an RV:
http://www.myrv.us/electric/Pg/open_neutral.htm

Mike Canter · 12-08-2010, 09:20 PM

Larry, a surge protector will not prevent damage in the case of an open neutral. We are kind of at the mercy of the electrons on this because you can't very well open up the box everytime before you plug in and check that everything is tight without getting zapped. That loose neutral connection will most likely work under a light load but will break down under a heavy load as talked about in the very good link that Gary provided for us. Your insurance should cover you on damage caused by this but you have to pay the deductable. If you can prove it is the campgrounds fault then you can probably get them to pay. Since nobody has done anything to fix your problem I would be concerned if you are still at the same campground plugged into the same box.

It might me a good idea to get an electrician to check that the leads on your power cable are tight where they attach to the MH and that the connections in the transfer switch are all tight as well as the main connections in the fuse box. If anybody is thinking about doing this themselves then they should understand all aspects of electrical safety and have the MH unplugged and the inverter totally shut down and test that everything is really shutdown before you touch anything.

TQ60 · 12-08-2010, 09:42 PM

The saandard is 240 VAC center tap, so 120 + 120 + 240

The current on the neutral wire is any that is not equal in both legs.

So if yo have only a 100 watt bulb on each leg then there would be zero curent on the neutral leg.

But if you had HVAC on one leg and the 100 watt bulb on the other the differene in load of the two devices would shift the effective voltage of both legs, one could be very low while the other would be very high. Remember the device plugged in completes the circuit, so the common point that would be connected to neutral/return would be floating and could drift towards either the +120 leg or the -120 leg, and with the line voltages being constant the voltage across either outlet is dependent on the combined loads on both phases, and can vary greatly and possible creat some damage.

LarryMars · 12-08-2010, 09:59 PM

Thanks, everyone. I read the two links posted by RVroamer and now feel like I understand what went on. I probably had my hot water heater on when I tripped the breaker and that was pretty much it, except for the converter and the volt meter. When the meter pegged, I turned everything off. Unplugging and replugging and opening and closing the breakers could have temporarily "fixed" the open ground. Then three weeks later, the ground reopened.
Since I am not 100% certain it not my coach, I am having an electrician come in from the outside, and I will be looking over his shoulder. I did move to a different site after the event. The park electrician has rebuilt the box, but says there was no problem with it. We are currently at a site with 30 amps, so I can not test my rig at 50 amps until I move.
Again, the help I received here was fantastic. Thanks.

bigskymt · 12-09-2010, 08:52 AM

Thanks Gary for those links. This being our first 50 amp M/H I'm unaware of many CG hazzards.

Mike Canter · 12-09-2010, 09:00 AM

Larry, if it was a barely loose or dirty connection in the box the park electrician probably would not notice it. He probably just made sure everything was tight. One thing to ask him is if any of the insulation was discolored by heat on the wires close to where they are connected. The problem is that the park electrician would not want to tell you that it was bad because then they have to fix your MH.