Generally, smart plugs are rated for a maximum power draw of 15A, so you should never use a smart plug for anything that draws more than that, like heavy appliances. Aside from amperage, there are other risks to consider before using a smart plug. These include unpredictable appliances, those that generate heat, and those that are high priority.

Note: Always check your smart plug's specifications and instructions to ensure you follow the manufacturer's guidance before using it.

Most smart plugs are rated for 15A, making them suitable for lamps, televisions, computers, fans, and other household devices. Even if you plug a smart plug into a 20A receptacle, its limit will remain at 15A, so you can't use it for heavier appliances, like full-size refrigerators and many A/C units.

Even if a heavy-duty appliance is turned on with a smart plug, you'll be pushing the plug to its limits, which can trip it, overheat its internal components, and degrade it over time. A high current can cause excessive heat at connection points, and many inexpensive smart plugs can't dissipate it effectively. If your smart plug emits a burnt smell or shows warping or burn marks, it means heat is building up inside, and you should not use it with that appliance.