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Electrical Discussion of preventative/corrective maintenance and other technical issues regarding your coach's electrical system.

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  #11  
Old 09-07-2009
GregRP GregRP is offline
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No. This coach has NEVER been able to connect to ground faulted shore power. Now I am planning on spending time at a place that ony has and requires a ground faulted shore power hook-up.

It is not the power cord. If I run the generator, then plug in it does not trip the gfci. Therefore, it is good from the plug to the switch-over relay. Also, with no generator running, both the 50 amp maincord and the 30 amp secondary cords trip the gfci.

I am still curious about the safe-line system; could it be tripping the gfci? Can anyone hookup a similar coach to a gfci shore power?
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Greg Peterson
1999 LXI 43'
Ridgefield, CT
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  #12  
Old 09-07-2009
davidmbrady
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Greg, I have never tried to plug into a 50 amp GFCI shore connection.
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  #13  
Old 09-07-2009
GregRP GregRP is offline
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David:
Have you tried plugging your '02 into a 15/20 amp GFCI shore connection?
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Greg Peterson
1999 LXI 43'
Ridgefield, CT
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  #14  
Old 09-07-2009
davidmbrady
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Greg,

I don't know. I may have but it didn't register.

I found this from the American Boat and Yacht Council (ABYC) on wiring Reverse Polarity Indicators (RPI's):

"The proper way to wire a reverse-polarity alarm is as described between the neutral and the grounding wire. The American Boat and Yacht Council (ABYC) standards specify that such a device should have a minimum resistance of 25,000 ohms. The reason for this is that if we apply Ohm's Law, assuming a 120-volt circuit, we find that, if the polarity is reversed, activating the device, the current flow will be 120/25,000 = 4.8 milliamps, which is just below the tripping threshold of U.S. Ground Fault Circuit Interrupters (GFCIs); they trip at 5 milliamps. This way the alarm will alert the operator without tripping the circuit."

Our RPI was made by PMMI, I assume they wired it with a 25K ohm resistor to prevent GFCI tripping (maybe a bad assumption), but if they didn't do it this way, it seems we would of heard of this problem long ago.

I think the circuitry is simply a 25K ohm resistor in series with an LED connected from the Hot Leads to ground and from the Neutral lead to ground. The panel is fitted to a 2 gang electrical box. It should be a simple matter to disconnect.

Last edited by davidmbrady; 09-07-2009 at 12:33 PM.
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  #15  
Old 09-07-2009
GregRP GregRP is offline
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Gentlemen:
Here is the latest. First, thank you for all of your contributions to date.

I disconnected the coach from shore power, opened the 110vac load center, placed an ohm meter between ground and neutral and got a low ohm reading. I removed neutral (white) wires from the bus until I got an open (infinite resistance) reading. One of the inverter ( there are 2) circuits was causing the low resistance to ground. I got excited, disconnected that one circuit, reconnected all of the others, checked resistance between ground and neutral and got an open (infinite resistance) reading. Then I connected the coach to a 15/20 amp GFCI shore connection and the GFCI TRIPPED instantly! So much for my excitement.

I also get an open (infinite resistance) reading on the male end of the shore power cord, but note that the change over relay is not activated.

Now what? I am beginning to suspect that I have two problems. One is obviously one of the inverter circuits(labeled battery charger in the load center) and I am beginning to think that the reverse polarity system is also contributing to my problem.

Does anyone know how I can temporarily disconnect that system? Atleast, can anyone tell me where to find the circuit board and box in which it is installed?

Again, I sure appreciate the exchange of ideas here on this site!
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Greg Peterson
1999 LXI 43'
Ridgefield, CT

Last edited by GregRP; 09-07-2009 at 01:05 PM. Reason: Added a second question
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  #16  
Old 09-07-2009
davidmbrady
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Greg,

When you ohmed out the neutral bar, were the house batteries disconnected? You have to first remove all power sources. If the house batteries were connected then there should be a neutral to ground bond at the source inverter. Remove all power sources and ohm it out again.
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  #17  
Old 09-07-2009
GregRP GregRP is offline
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David.
The house batteries were connected and, thus, the inverters were operating. This may explain the neutral-to-ground reading that I got one one inverter. But, with that inverter removed from the 110vac load center and the load center now reading open between ground and neutral, I should be able to connect to a GFCI.

I will check the disconnected circuit with batteries disconnected before I do any work on that circuit.
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Greg Peterson
1999 LXI 43'
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  #18  
Old 09-07-2009
davidmbrady
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I see what you mean, but try it again with the batteries disconnected.

When the inverters are the source then the inverter bonds neutral to ground. When shore power is the source, then shore bonds neutral to ground and the inverters unbond. When the genny is the source, then the genny bonds neutral to ground and the inverter unbonds and the transfer switch disconnects shore power. When the genny is off and the shore is disconnected and the house batteries are charged, then the inverter inverts and bonds neutral to ground.

I suspect an appliance (microwave) or an existing GFCI inside the coach somewhere. Someone may have wired one incorrectly. Has any appliance been misbehaving lately, or has anyone rewired anything lately?

With that one inverter removed, the other inverter took over.

The PMMI RPI circuitry should be at the PMMI monitor LEDs by the glendenning power shore cord reel.

We're all learning. :-)

Last edited by davidmbrady; 09-07-2009 at 02:34 PM.
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  #19  
Old 09-07-2009
davidmbrady
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I'm wondering if there are some circuits that aren't powered by the inverters, are only powered by shore power, and that might not go thru the load center. The only one I can think of that might be a possibility is the one in the first basement bay, driver's side, that the radioshack converter plugs into so that the Westhaver gencon can monitor blackouts.
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  #20  
Old 09-07-2009
GregRP GregRP is offline
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I disconnected the safeline alarm ( thinking it might be the PMMI) which is located by the transfer switch. After doing so, the coach stayed connected to a GFCI shore power connection for about 15 seconds before tripping the GFCI.

I have since unplugged the generator auto start from the outlet in the forward LH compartment, unpluged the constahot, and the GFCI trips immediately, again.

Boy is this frustrating!

Ever onward!
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