You've hit upon a valid and often overlooked point regarding GFCI compatibility with older inverter technology. The short answer is: No, there are no commercially available GFCI receptacles that are specifically "listed" or "approved" for use with square wave inverters in the way that the ABYC statement implies.

Here's a breakdown of why and what you should do: The Problem

Standard GFCI receptacles are designed to operate with a sinusoidal (sine) waveform. Square wave inverters, as the name implies, produce a square waveform. This sharp-edged waveform can:

Cause the GFCI to trip nuisance trips

The GFCI may interpret the non-sinusoidal waveform as a fault condition, leading to frequent and frustrating tripping.

Damage the GFCI

The electronics within the GFCI may not be designed to handle the rapid voltage changes inherent in a square wave, potentially leading to premature failure.

Prevent proper GFCI function

The GFCI may not be able to accurately detect ground faults with a square wave input, defeating its purpose of safety.

"Square Wave Approved" Myth

There is no recognized standard or certification for GFCI receptacles to be "approved" for square wave inverters. Manufacturers of GFCI devices typically do not test or certify their products for use with non-sinusoidal waveforms.

What ABYC is Likely Trying to Convey (and Why It's Tricky)

ABYC's statement isn't wrong, but it's poorly worded. What they likely mean is that you need to be extra cautious when using GFCI protection with square wave inverters. They are hinting that some GFCIs might seem to work better than others, but there's no guarantee.

The REAL Solutions (In Order of Preference)


Replace the Inverter with a Pure Sine Wave Inverter

This is the

best and safest solution. Pure sine wave inverters produce a waveform that is virtually identical to utility power, and GFCIs will function correctly and reliably. This is almost always the recommended upgrade path. These are readily available and have come down in price significantly.2. Replace the Inverter with a Modified Sine Wave Inverter

A modified sine wave inverter produces a voltage waveform which stays at zero volts for a brief period between each half cycle. This waveform is more similar to a sine wave than a square wave is. It is less stressful to GFCIs and other electronics than a square wave is, but it can still cause problems.3.

Bypass GFCI Protection (Not Recommended, and Potentially Violates Codes)

This is generally not recommended due to the safety implications. Removing GFCI protection increases the risk of electric shock. This should only be considered in very specific, controlled situations and only after a thorough risk assessment. Furthermore, it may violate ABYC and/or local electrical codes. Never bypass GFCI protection without understanding the risks and ensuring compliance with all applicable regulations.4.

Experiment (With Caution and Limited Applicability)

In very limited circumstances, and only with a deep understanding of electrical systems, you might be able to try different GFCI brands/models to see if any seem less prone to nuisance tripping with your square wave inverter. However:

This is NOT a guarantee of proper GFCI function. It's simply an attempt to find a combination that's less problematic. You still need to test the GFCI regularly to ensure it's tripping when a fault is present. This is NOT a substitute for a proper sine wave inverter. Key Takeaways



Square wave inverters and GFCIs are a problematic combination. Avoid them if possible. There are no "approved" GFCI receptacles for square wave inverters. Prioritize safety and code compliance.* Upgrade to a pure sine wave inverter whenever feasible.In conclusion, do not rely on finding a "special" GFCI for square wave inverters. The only reliable solution is to replace the inverter with a pure sine wave model. This is the safest and most effective way to ensure proper GFCI function and electrical safety on your boat. Flag for review