Yes, it's entirely possible you have a defective GFCI breaker that's tripping too easily. Your troubleshooting steps strongly suggest this is the case. Here's a breakdown of why and what you can do

Why a Defective Breaker is Likely:
Isolation of the Problem

You've systematically eliminated other common causes:

Not the Circuit

The planer works fine on other circuits, proving the wiring itself is not the issue.

Not the Receptacle

You checked for shorts and loose connections.

Not the Planer Itself (Necessarily)

The planer runs without tripping on other circuits.

The Breaker Travels with the Issue

This is the strongest evidence. When you swap the breaker, the problem moves with it.

Inrush Current and GFCI Sensitivity

Electric motors, especially large ones like your 5HP planer, have a significant "inrush current" when starting. This is a surge of current much higher than the running current. GFCI breakers are designed to detect small imbalances in current, but sometimes the inrush can create a slight imbalance, even if there isn't a true ground fault. A perfectly functioning GFCI should be able to tolerate the inrush of a properly wired motor without tripping unless there's an actual ground fault. A sensitive or weak GFCI breaker might trip unnecessarily on the inrush. This is especially true if it's near the lower end of its tolerance range.

Why the Tablesaw Doesn't Trip It



Lower Inrush Current

Your 3HP tablesaw has a smaller motor and therefore a lower inrush current. It's within the tolerance range of the GFCI breaker.

What to Do Next


Replace the Breaker

This is the most logical step. Since the problem follows the breaker, replacing it is the best way to confirm the diagnosis. Get an identical Square D Homeline 30A 2-pole GFCI breaker.2.

Document Everything

Keep a record of your troubleshooting steps and the results. This is helpful for warranty claims if necessary.3.

Return the Defective Breaker

If you bought the breaker recently, contact the retailer (or Square D directly) about a warranty replacement. Let them know the troubleshooting steps you took.

Important Considerations



Proper Wiring

Even though you checked, double-check that the wiring to the receptacle and the wiring inside the planer's junction box are correctly wired according to code. Verify the grounding wire is properly connected.

GFCI Sensitivity: If the new breaker still trips intermittently, even though it's brand new, it might* point to a very small amount of leakage current from the planer itself that is within tolerances for some breakers but not for others. While the planer is new, manufacturing issues can happen. In this very unlikely instance, you might want to have an electrician test the planer for leakage current.By replacing the breaker, you'll almost certainly solve the problem. A defective breaker is the most probable cause given the troubleshooting you've already done. Flag for review