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

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  #21  
Old 09-07-2009
GregRP GregRP is offline
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Another Update:
I reconnected all circuits in the 110vac load center, set the inverters to a 5 amp connection (to prevent overloading my 15 amp GFCI shore power connection).

I disconnected the RPI located in the shore cord reel compartment. Note that the safeline is still disconnected at the switch over relay.

Now, the coach stays connected to the GFCI shore power for almost 2 full minutes. Whoopee.

My thinking is to disconnected the RPI located over the front entrance door. I am wondering if two RPI's can trip the GFCI? I originally thought that we had just one RPI, with two sets of indicator lights. We do not. We have two RPI's, 1 at the cord reel compartment and 1 over the entrance door. I notice that the yellow (OK) light on the RPI over the entrance door maintains a slight glow even with no shore power and a bright glow when connected to shore power. Ever hopeful, I continue.
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  #22  
Old 09-07-2009
davidmbrady
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Greg,

I'm beginning to think this is futile. A GFCI works by comparing current on the hot lead with current on the neutral lead. If there's a difference as small as 4mA the GFCI may trip, at 6mA it will trip. I think in a motorhome there are simply too many places for leakage currents to ground to take place. There's leakage in every wire, receptacle, appliance, inverter, converter, charger, and even the PMMI polarity detectors themselves (for example, the flickering of the detector that you noticed when not connected to shore power), and all that's required to trip the GFCI is 4mA. I think the reality is that you won't be able to stop the accumulated sum of small leakages that's tripping your GFCI! I don't think there's a BB in existence that won't trip your GFCI.

The NEC code requires that a motorhome look like a UL Appliance. Imagine comparing your motorhome with a microwave oven that you plug into a GFCI. If you model a motorhome as a power consuming load, taking in a neutral, a power, and ground lead, given the complexity of this appliance, you'd have to draw a resistor to ground to model the expected leakage currents. These accumulated leakage currents are sure to top 4mA.

Look at this:
http://www.xantrex.com/support/readf...?did=267&p=589

Last edited by davidmbrady; 09-07-2009 at 05:36 PM.
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  #23  
Old 09-07-2009
GregRP GregRP is offline
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David:

Interesting link. It would certainly lead me to conclude that TWO RPI's could definitely cause a GFCI to trip, especially combined with any other small leaks. Then add the SafeAlarm and the three small loads could definitely cause the GFCI to trip.

I have come so far that I am going to try the step of disconnecting the RPI over the entrance door. I will keep this thread up to date; however, I am done for the day. Hopefully, tomorrow I will get a chance to explore.

Since I am getting such completely open Ohm meter readings, I believe the coach wiring to be as clean as possible.

At the place I plan on visiting, SOB's are connected to GFCI"s; however, I have not seen any buses there, just fiberglasss motorhomes and trailers.

I truly appreciate your postings. Someday I would certainly enjoy meeting you.
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  #24  
Old 09-07-2009
davidmbrady
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Quote:
Originally Posted by GregRP View Post
I truly appreciate your postings. Someday I would certainly enjoy meeting you.
Same here Greg, and welcome to the forum. I enjoyed today's exercise immensely. It's always fun getting to know our buses better.

I think instead of trying to reduce the leakage currents, an interesting idea might be to try to defeat the GFCI. All it wants is the same current on the power as on the neutral. The proper way to do this is to use an isolating transformer, there may be other ways...
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  #25  
Old 09-07-2009
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Greg,
When checking continuity on those circuits make sure your ohm meter is on it's highest setting. You don't want 1X or 10X go for 100X or 1000X if you have it, this gets the really small leakages.
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  #26  
Old 09-07-2009
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I don't claim to know anything about the electrical system on the newer 'Birds but this has been a very common problem with older 'Birds when trying to plug into a GFI protected outlet and on mine and others has been easily fixed by PMMI, could this be a related problem on the later model 'Birds?

Wanderlodge Owners Group > Mechanic's Corner > Electrical > Polarity Monitors tripping GFI outlets on Early Model 'Birds
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  #27  
Old 09-07-2009
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John,
I seem to recall that when PMMI did the fix they changed the led(s) color to yellow, indicating that the GFI fix has been taken car of. In our coach the led(s) are yellow.

What color led(s) do you have, others?
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  #28  
Old 09-07-2009
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Quote:
Originally Posted by curtsprenger View Post
John,
I seem to recall that when PMMI did the fix they changed the led(s) color to yellow, indicating that the GFI fix has been taken car of. In our coach the led(s) are yellow.

What color led(s) do you have, others?

Curt,

That's a good point, my Polarity NORMAL led's have also been changed to AMBER/YELLOW while the Polarity Reversed remained RED. I have added that information to the link that I had previously supplied.
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JOHN FINN
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1982 FC35RB
I'm NO EXPERT, but I did stay in the FINN'S INN EXPRESS last night
HOPKINS, SOUTH CAROLINA
VISIT THE FINN'S INN EXPRESS REMODELING ADVENTURE AND TECH. TIPS
I'M SO SLOW ON THE HILLS,THAT I GET TO SMELL THE FLOWERS AS I GO BY.....AND WATCH THEM GROW TOO!! NOT SO MUCH ANYMORE
Visit the WILD HARE RACING website
REMEMBER 9/11
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  #29  
Old 09-08-2009
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I got in touch with PMMI this morning. All the RPI sensors with yellow LED's use a 168K ohm resistor in series with the LED. For line voltage of 110V AC this limits current to 0.7mA. The LXi uses 2 RPI's so we have twice the current draw or 1.4mA, far less than required to trip the shore GFCI. PMMI confirmed that the circuitry is simply an LED in series with a resistor connected from Line voltage to Ground and from Neutral to Ground.
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  #30  
Old 09-08-2009
GregRP GregRP is offline
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The Final Conclusion:
I went through the effort (really not easy) to disconnect both RPI's and the SafeLine Alarm. I also measured a completely open (infinite resistance) relationship between neutral and ground in the 110vac load center. I measured this resistance, or lack thereof, with a high quality meter set on 20M ohms.
The result, I cannot connect my 1999 LXi to a 15/20 amp 110vac GFCI.

Now, I guess I need to pursue the route of isolation.

Does anyone have ideas of where/what to buy in the line of isolation transformers? I don't want to spend a fortune and I certainly do not need 50amps; 30 would be good.
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