Why is a GFCI tripping when I connect a hot plate?

Heating elements are one of the most common causes of GFCI trips because resistive heating coils naturally leak a small amount of current to the metal housing as the element heats and cools, and that leakage often lands right around the 4 to 6 milliamp range a Class A GFCI is designed to sense. A GFCI is doing its job correctly when it trips on this kind of leakage, it does not mean the device is bad, it usually means the appliance has developed a real path to ground.

What is actually happening inside the appliance

As a heating element ages, the insulation between the resistive coil and the metal sheath breaks down from repeated thermal cycling. Moisture from cooking, grease buildup, or a damaged cord can accelerate this. The current that leaks through that degraded insulation to the appliance frame, and from there to ground through the equipment grounding conductor, is exactly the imbalance between hot and neutral that a GFCI measures on every half cycle.

Confirming the appliance, not the device

Test the receptacle with a different load, a lamp or a hair dryer works fine, to confirm the GFCI itself is not oversensitive or defective. If the receptacle holds with another load and only trips with the hot plate, the appliance is the source. An insulation resistance test on the heating element with a megohmmeter will usually show a reading well below what a healthy element reads, confirming the internal fault.

Field takeaway

A GFCI tripping on a hot plate is more often a real fault in the appliance than a defective device. Rule out the receptacle with a known good load first, then treat the appliance as needing service or replacement rather than looking for a way around the protection.