Why does a residential fridge trip my GFCI?
A question from the Hershey show that I wasn’t able to answer definitively…. Please take this poll!
Dear Readers,
I’m having fun teaching and answering questions about RV electricity at the Hershey RV show this week. Most questions were pretty easy to answer, but this one stumped both me and my colleague Chris Dougherty. But we have a few possible answers.
The Basics
Residential refrigerators in RVs don’t need to be plugged into a GFCI protected receptacle as long as the receptacle is not accessible from the living space. That’s because the 120-volt compressors in the fridge can cause nuisance tripping of the GFCI.
The Problem
But it appears that some RV manufacturers are plugging their refrigerators into a GFCI branch circuit that’s powered by the inverter. And that’s causing problems when the RVers head out for the day and come back to a tripped GFCI and a warm fridge full of spoiled good.
Why it Trips…
I’m not sure, by my guess is that this nuisance tripping may be caused by a Back EMF voltage spike when the compressor starting relay opens up. This will generate lots of high frequency harmonics in the AC wiring that may be fooling the GFCI sensing circuit into thinking there’s an actual fault current over 5 mA.
And that Back EMF pulse could be causing the GFCI nuisance trip, which is why residential refrigerators are exempt from being plugged into a GFCI circuit.
Chris and I have brainstormed this and there may be a simple solution. But we need to know more about how often this nuisance tripping actually occurs. That’s why we need your help.
User Data Needed
So please answer this poll and let me know if your residential refrigerator is plugged into a GFCI protected circuit in your RV, and if it’s ever caused a nuisance trip. And add any details in the comments below.
Let’s play safe out there - Mike
I do believe it’s due to the inductive kick of the starting the compressor. My daughter has 2 very large ceiling fans In her screened porch, if both are set to high speed when she turns on the switch it trips the GFCI, if both are on the low setting everything is fine. After starting the fans she can then set the fan speed to high without issues.
I know this is small stuff but when you start the compressor there is a certain amount of motor field magnetizing current that may appear to a very sensitive GFCI that is not coming back. Conversely if there is a blip in the supply then as the field begins to collapse in the motor there could be a small imbalance there too. I’m more familiar with large industrial motors so I may be way off base here?