GFCI on inverter

[Gin]

I rarely use my inverter. My biggest use of it is this time of year, to power my decorative display during the Portland (OR) Christmas Ships parade season. The load on it is not huge -- my lights are all LEDs and, combined, require only about 160 watts. Still, on occasion, without a pattern that I can identify, the GFCI on the inverter will trip about 1/2 to 1 hr into the evening's parade. Because of the logistics of resetting it, when it trips, I cut over to a gas powered Honda generator for the rest of the parade. Last year, it happened about 3 out of 14 nights of parading. This year, it happened on the second night out. It reset fine after the cruise that night.

Via internet research, I've learned that inverter GFCIs can be prone to tripping if there are GFCI's installed downstream, as our boats have in the port and starboard circuits. But those need to be there to have GFCI protection on shore power.

So I called ProMariner, which makes the Truepower 1500 installed on my boat. The support agent suggested he had never heard of a GFCI tripping unless the GFCI has gone bad, in which case he thought the GFCI would be tripping anytime there is a load on it. Mine works well more times than not. He told me I could send the unit to them to check the GFCI, and otherwise didn't have any ideas or offer any help.

I may just run off the generator rather than risk a mid-parade blackout each night we go out. But I'd prefer to use the inverter. It's more convenient and that's what it's there for, after all.

I'm wondering if anyone on the forum has had this issue and knows of or has thoughts about a solution.

Thanks all.

Gini

 

[Andrew Custis]

Hello Gini,

Been a long time. Hope all is well. I would be curious to know if other devices will run on the inverter for a longer period of time. Sometimes items with sensitive electronics can have a tough time working on a modified sine wave inverter which is what you have installed. If you could try running other things other than the Christmas gear such as a standard coffee maker (without the fancy electronics in it) and report back, that would give us a good idea of whether or not it could be a bad GFCI or not.

Thanks Gini,

 

[Red Raven]

Hi Gini,

Perhaps the Christmas lights are getting wet? Rain? A little mist? Even from evening dew? GFCIs are pretty sensitive and any moisture across the circuit would likely trip it.

Curt

 

[Gin]

Andrew, great to hear from you! I will test out other things and let you know. We move the fleet during the day this Saturday to St Helens, OR for a weekend there. That day move will give me a good opportunity to runs some other things on the inverter and see if it trips. I'm not sure my LED strings qualify as fancy electronics. Maybe they do, though, and I hadn't thought of that. Most of the display consists of single color rope light (simple on/off stuff, not the chasing or dimming or color changing kind). I do have some fancier tape light around the cabin and the hull that permits some special effects.

Curt, yes, the moisture question is a good one. That was what I wondered when it happened the first time last year. It was raining on that night. But I didn't find any moisture in the inverter area (I have a canvas enclosure on the cockpit that keeps things very dry except over by the doors as we board and get off). When it tripped Saturday night, it was a beautiful dry cruise. I checked for moisture when we got back to the dock and didn't find any.

Back to you Andrew, I'll run a few things on the system and see what happens. Thanks!

Gini

 

[Red Raven]

Gini,

The moisture could be anywhere along the string of lights and not necessarily anywhere near the inverter. A slight difference in current between the positive and negative caused by leakage current to a “grounded” surface (tied back to negative battery terminal) would do it. Note that the water you are floating on is grounded to your boat via the underwater bonded metal so this is pretty easy to imagine. If it persists you might try disconnecting each string one at a time to determine the culprit that is exposed to the moisture.

Curt

 

[Gin]

Hi again Curt.

Ah, good to know. Yes, some of the lights get wet. Even in the driest of weather, I get at least some splash moisture on the lights on the hull, particularly the rear swim step. So if that would do it, the conditions to trip it would be there.

That said, I have not had the inverter trip the past two nights. And last night would have been a prime night if the splash is enough to do it. Our route for the night was through downtown Portland, under about 8 of the bridges. The trip back upriver under the bridges is always like negotiating small rapids by the time we push through the higher currents under the bridges and our wakes reverberate against the urban seawalls that line that part of the river. Plenty of moisture from the splash on the hull and back swim step (in fact, another boater found his swimstep covered in ice after the cruise last night).

But I've thrown a new factor into the mix. I moved the plug for the AC panel from the lower outlet on the converter (where it covered the second upper outlet) to the upper outlet. Not easy to do, given the thickness of that cord and the fact that it is cut to exact length and fastened securely. But I was able to inch it up just enough to plug it into the upper outlet, which let me put a short extension cord on the lower one. I ran that up into the cockpit (routing it between the hull and inner shell behind the rear starboard speaker). My display is plugged in through that connection. The net effect is that the inverter is directly powering the display, rather than getting the power after the AC panel through one of the two circuits that have their own GFCI. If the problem is having more than one GFCI on the line, I thought maybe that would be a solution.

So far, so good. But to go several nights without it tripping isn't new. That's what it has done before -- trip occasionally, not routinely or regularly.

I'm only four nights into the fifteen night season, so the experiment continues. Our dry cold weather here is about to end as well. Our longest parade of the season will be Sunday, and it looks like steady rain that day and night. That will be a good test for sure. And per Andrew's earlier suggestion, tomorrow on the day trip up to St Helens, I'll try running some standard appliances and see if the inverter trips at all.

I'll report back!

Gini

 

[Gin]

For anyone interested in the upshot of my inverter issue . . .

The inverter works fine running regular small appliances underway. No tripping of the GFCI. So it passed the test Andrew suggested I run. Meanwhile, I have now powered my seasonal display for several nights using the inverter, but running the power to the display directly from the inverter's GFCI. Yesterday was a great test for it. We were on the water during the day to move the parade to a new location on the Columbia. Between the day cruise and the nighttime parade, the inverter powered the display for nearly 7 hours. Rain was steady all day and through most of the night's parade. The inverter powered the display the entire time. And it has now down so for several nights running, in dry to very wet conditions, for stretches of time ranging from around 2 hours to 7 hours. The GFCI has not tripped under any of those circumstances.

So, the problem appears to be powering the LED display via the inverter when the circuit has another GFCI down the line from the inverter's GFCI (this blogpost describes the problem: https://blog.donrowe.com/2017/06/15/power-inverters-and-gfci-tripping/). Happily, the same problem doesn't occur with regular appliances. So if it is something distinct to the combination of the LEDs and the modified sine wave the inverter puts out, at least there is an easy workaround for me during the parade activities.

If anything changes in the remaining two weeks of parading, I'll post about it. In the meantime, I hope that provides someone with some helpful information if they ever run into a similar problem.

Gini