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garry · 08-09-2009, 08:42 PM

Dave,
From what I understand the GFCI breaker only trips when the converter is plugged in.

That tells me the converter has an open neutral or internal short.
The short only has to be a very slight current leak (.001 amps can do it).

You may have to take the converter out and test it on a GFCI in the house.

Garry

GFCI do go bad but not very often and it sounds as it is designed to.

Garry

Dave Jenkins · 08-10-2009, 06:10 AM

Hi Garry - thanks.

I have all along thought it was the converter. You understand correctly. The breaker in question only trips when the converter is physically plugged in, or when it is already plugged in, and I connect to shore power. That is, it only trips when 120V AC is first applied to the converter.

The thing that has given me pause in this (due to ignorance on my part) is the issue of which breaker is tripping. My control panel has 5 breakers. The converter receptacle (along with some others) is on one 20A breaker. There is another 20A breaker with GFCI that controls receptacles that are in places where there's liable to be water involved (bath, galley, etc.). That's the breaker that trips.

So if I've been wondering all along if that's expected behavior or not: A short on a device (converter) on one circuit trips a breaker in a different circuit. If that's normal behavior, then I think it's the converter; but if that says there's something else wrong, then I need to keep looking.

Can you provide any insight on that issue, Garry?

Thanks!

Dave Jenkins · 08-10-2009, 01:26 PM

I may be closer to getting a resolution to this:

I called the Parallax manufacturer (or maybe their reps: Connecticut Electric) to get some help, and they suggested some additional diagnostic tests. I’ve tried to call them back twice to report on what I found, but haven’t been able to reach anyone.

Here’s what I did, and what happened:

1. Tested each of the three other circuits (but not the one the converter is on, and not the one that the GFCI breaker is on) by removing each circuit's neutral connection. The GFCI breaker continued to trip when the converter was plugged in. I guess that tells me that nothing on any of those three circuits is affecting the breaker tripping - right?

2. I bought an inline GFCI tester and put it in a line I ran from a Honda generator. Nothing else was running off the generator, and when I plugged in the converter to that generator, the inline GFCI tester tripped.

If I interpret all of that correctly, that seems to point specifically to the converter as the source of the GFIs, to me. But I’m open to a different interpretation, or conducting any further tests that you all want to suggest.

What do you think?

Dakota's Dad · 08-10-2009, 01:48 PM

just a note.. when testing the 12v DC circuit, you are seeing 27v AC, because your meter cant read DC when in the AC setting. There is a setting on your meter for DC, use that setting when checking DC, and the AC setting when checking AC circuits.

as a side test, I would take the converter home, and plug it in to a GFCI circuit there and see what happens. Although I guess this pretty much the same as the generator test. Does your Honda generator have GFCI protected circuits? I know my generator does, did the converter trip those? or just the inline?

richinny · 08-10-2009, 02:09 PM

related post:
http://www.airforums.com/forums/f449...gfi-43187.html

Dave Jenkins · 08-10-2009, 02:14 PM

Thanks, Dakota's Dad.

The little Honda generator i was using showed an open ground, thereby casting the results of that test in doubt. (I was told.) However, I then disconnected the AS from shore power, connected the converter to the building power through the inline GFCI tester, and it tripped (while, as to be expected, nothing in the trailer tripped). With the trailer on shore power, the converter connected to inline GFCI tester, both GFCIs tripped. Don't know in what order.

I'm told by the Parallax Power guy (who has been *extremely* helpful) that this would be only the second one he's seen in 10 years with this particular problem. I just hope that I've faithfully followed all the problem isolation procedures folks have suggested, and that I haven't done something stupid to lead to the faulty converter conclusion.

I will be ordering a warranty replacement unit shortly, and will update this thread once it's installed.

Thanks!

Dave Jenkins · 08-10-2009, 02:26 PM

Hi Ricky:

Thanks for pointer to that earlier thread. No one else seems to have the identical symptoms that I've been having: Converter is on a non-GFI circuit, but trips the breaker on a separate GFI-protected circuit.

Some of my most recent posts may shed some light on what I've found out so far. One thing I have NOT done is to swap out the GFI breaker. I have one, but it's too darn hot in this part of Texas to do that now. Later, maybe.

wmarsha · 08-10-2009, 02:31 PM

dave, the gfci only trips when it senses current flow on the grounding conductor. The reason you don't know which gfci breaker is tripping, is because all of the grounding conductors within your trailer are connected together. There is current running in the grounding system within your trailer. There is a spike in that current when you change from shore/gen/and back. The only place the neutral and grounding system are bonded together is at a shore line main panel. So, there is possibly a "downstream" connection between the neutral and the grounding system. This causes a "fault" condition and the gfci will operate. The very early gfci were prone to failure, the newer ones not so much. the extra confusion comes because the problematic device is the charger-which you should isolate from the 12dc load side and then just energize the charger-such isolation would determine if the 12vdc load side is the source of the grounding system current, or if the charger has suffered some kind of internal fault. once isolated from the 12vdc load, if the gfci operation still continues, then there is a problem internal to the charger. if the problem goes away, while isolated from the 12vdc load, then there is a wiring problem on the 12vdc side. I am going back to reread your posts and may edit this for clarity.
bill
yeah, reread them and eliminated the a/c as the cause. The only time the gfci operates is when shore line is connected-this confirms the idea that there is current in the grounding system, only causing the gfci to operate when connected to a 120vac source that has the neutral and grounding system bonded correctly. a portable generator does not have such a bond. so do the isolation to determine if the problem is in the charger (12vdc source) or the 12vdc load side. The question is: what changed? Has there been any 12vdc work done lately?

Dave Jenkins · 08-10-2009, 03:51 PM

Hi Wmarsha:

Thanks for the explanations.

Some responses:

1. Yes, the AC was replaced rather recently. It's controlled via a digital thermostat - don't know if there's any 12V involvement there or not.
2. I removed the converter from the trailer altogether, and connected it to a shore 110VAC outlet, via the inline GFCI, which tripped when I plugged in the converter. That would eliminate 12V for sure, I would think.

The unit is under warranty, and the Parallax Power Systems guy I talked to couldn't think of any more diagnostic procedures ... so I've requested an RGA.

Thanks for your interest and suggestions.

wmarsha · 08-10-2009, 04:09 PM

all of that, and it was right where you initially thought! good for you!
cheers
bill

Gene · 08-14-2009, 09:16 AM

Dave, congratulations for sticking with this somewhat crazy problem and is does appear, as bill says, you figured it out right away. Trailer electrical systems are very, very confusing.

Gene

Dave Jenkins · 08-14-2009, 10:11 AM

Thanks, Gene.

The saga is almost over - the replacement converter was airshipped but UPS tried to deliver to wrong city. We still haven't received it!

But I'm hopeful it will go in easily (once it gets here) and we can be on our way.

tallytwo1994 · 08-14-2009, 10:43 AM

Makes me wonder why the Camping World tech thought it was an AC problem. Was the circuit tripping when it was at Camping World? If so, it doesn't seem logical they would have thought the problem was solved when the replaced the AC. Surely they tested everything once the AC was replaced, and if the circuit wasn't tripping then it seems to me the problem was back at home.

Did you actually test the trailer somewhere other than your own house? If not how did you eliminate that as the the source of your problem.

Carol

sander17 · 08-14-2009, 10:56 AM

Earlier in the thread a comment was made about voltmeters. In the DC and in the AC volts measurement setting, non-broken VOMs have a high impedance on the leads, usually at least 50,000 ohms per volt. This means you can probe any circuit that has less than 600 volts on it without affecting the circuit itself.

Where you want to be super careful is in the AMPs switch position. In this position, the VOM looks like a dead short to any circuit and things can get dramatic quickly. Because of this, some VOMs have an internal 10 amp fuse in-line with the leads when in this mode.

As always, if you are nervous about dealing with an electrical problem, seek out help from an experienced friend. That little nervous voice in your head could save your life!

Dave Jenkins · 08-14-2009, 11:00 AM

Hi Carol:

To answer your second question first: I tested the converter outside of the trailer, and with the trailer disconnected from 120 altogether.

Camping World did not replace the AC - they just diagnosed it as being bad. They (and other dealers, too) have had troubles with the Dometic supply chain, due to a fire at the Dometic factory. CW was entirely unhelpful about finding a replacement unit, anyplace in the US, so I was on my own as far as that was concerned. I finally found a unit about 90 mi. from here (Buda, TX) and they did the actual replacement.

In retrospect, and of course with 20-20 hindsight, it may be that CW misdiagnosed the original problem. We took it to them for the following symptoms: breaker tripping (same GFCI breaker) and compressor not coming on. It may well be (but we'll never know) that either we misreported the compressor problem, or somehow (I don't know how that would work) the tripped GFCI caused that compressor not to run. (With the new AC installed, even though the converter/GFCI problem still existed, the new AC runs like a champ.)